Piston Rings

March 5, 2021

 

Listed as: D x h x w xxx Listed as: D x h1/h2 x w xxx Listed as: D x h1/h2 x w1/w2 xxx Listed as: N or  I xxxxxxxxxxx

GN gap (aka FG)
pin on side of groove

 

Meanings:
D
is the cylinder diameter that the ring would have a 0.004 to 0.008″ gap in
height is the thickness up-and-down. T & L rings have 2 heights, outer & inner
width is the depth inward-and-out. L rings have two widths, outer and inner
type C = Common “square”  shape (cross-section)
type T = Trapezoidal “slant top” shape (cross-section)
type L = L-shape  aka  “Dykes”  shape (cross-section)

GI gap style
pin inside groove

gap GN Grano Normale gap style is for ring pin on side of ring groove
gap GI  Grano Interno = gap style is for ring pin in center of ring groove
gap (blank) is for L-ring gap style, ring is like a GI but groove is like a GN
price is for each ring, unless noted.  All rings are for 50cc engines, unless noted.

                           R I N G S

0  size x height x width  type gap price     part number  applications
36.50
 x 1.50 1./x 1.7/0.7  C  N  $10.0 0 0000  222812 Tomos MC36 36cc
38.00 x 1.50 1./x 1.7/0.7  C   I   $10.0 0 0215.100.100 Sachs 1979-on 504,505 1C,1D upper
38.00 x 1.50 1./x 1.7/0.7  C  N  cont..  00.. 000000000 Zanetti (front engine)
38.00 x 1.5/1.3 x 1.60 /7  T  N  $17.0 0..0000 223707 Tomos A55 (2001-06) superseded in ’07 to 236802
38.00 x 1.50 1./x 1.7/0.7  C  N  $$9.0 0..0000 236802 Tomos A35 (1991-06), Tomos A55 (2007-on)
38.00 x 1.50 1./x 1.7/0.7  C  N  cont..  0 000.672.5110 Derbi 1976-1986 lower only, Odyssey, Solo
38.00 x 2.0/1.0 x 1.5/0.5  L  N  $10.0 0 000.802.5110 Derbi 1976-1986 upper (fits Puch loose inner)
38.00 x 2.0/1.0 x 1.7/0.7  L  N  $21.0 0 328.110.9601 Puch 1979-1980 deluxe models upper
38.00 x 2.00 1./x 1.7/0.7  $13.0 0 331.110.1601 Puch rounded edge for aluminum cylinder
38.00 x 2.00 1./x 1.7/0.7  $$9.0 0 320.110.0601 Puch except some ’79-80 upper
38.00 x 2.00 1./x 1.7/0.7  C  N  cont..  0 0215.009.000 Sachs 504, 505 1A,1B both, 1C,1D lower
38.00 x 2.00 1./x 1.7/0.7  C  N  cont..  0..0000 044754 Tomos A3 1975-1990, AMF BHE900 rear engine
38.00 x 2.00 1./x 1.7/0.7  C  N  cont..  00.000 26.1001 Morini S5K, S5K2, 2M, 3M, F48
38.00 x 2.50 x 1.50.7/0.7  C  N  $11.0 71.0802.0 4600 Minarelli V1 1hp 20mph, Sears Allstate, early Puch
38.00 x 2.50 1./x 1.7/0.7  C flat  N/A     0.00000000000 Solex 45cc 1946-1954  use 38.00 x 2.50 C N
38.20 x 1.50 1./x 1.7/0.7  C  N  $10.0 0..0000 182518 Piaggio 79-later & some 78s lower ring
38.20 x 2.00 1./x 1.7/0.7  C  N  $16.0 00..000 166945 Piaggio 78-80 USA-type, must file down a 077775
38.00 x 2.00 1./x 1.7/0.7  C  N  cont..  0000.0 26.1002 1os Morini S5K, S5K2, 2M, 3M, F48
38.20 x 2.0/1.0 x 1.8/.75  L  N  $14.0 0..0 000182519 Piaggio 79-later & some 78s upper ring
38.20 x 2.50 x 1.50.7/0.7  C  N  none.. 71.0852.7 4610 Minarelli 1os V1 1hp 20mph, Sears Allstate, early Puch
38.25 x 2.00 1./x 1.7/0.7  C  N  $16

38.25 x 2.0/1.0 x 1.5/0.5  L  N  $11.0 000.802.5110 1os Derbi 1976-1986 upper ring
38.25 x 1.50 1./x 1.7/0.7  C  N  $15.0 0 000.672.2511 1os Derbi lower
38.40 x 1.50 1./x 1.7/0.7  C  N  $14.0 00 000  132515 std or 1os Piaggio lower ring, 79-later & some 78s
38.40 x 1.5/1.3 x 1.60 /7  T  N   N/A    0 000   3010010 Kinetic TFR (Vespa Si remake) 95-later
38.40 x 2.00 1./x 1.7/0.7  C  N  $12.0 0 0000  077775 Piaggio 77-earlier & some 78s, early Kinetic
38.40 x 2.0/1.0 x 1.8/.75  L  N  none.. 0 000   G.68473 std or 1os Piaggio upper ring, 79-later & some 78s
38.40 x 2.50 x 1.50.7/0.7  C  N  $9.00 71.0852.7 4620 Minarelli 2os V1 1hp 20mph, Sears Allstate, early Puch
38.50 x 1.50 1./x 1.7/0.7  C  N  $12.0 0 0000  227758 1os Tomos A35
38.50 x 2.00 1./x 1.7/0.7  C  N  $10.0 0 0000  044751 1os Tomos A3
38.60 x 1.50 1./x 1.7/0.7  C  N  $9.00 000000 137693 1os or 2os Piaggio  
38.60 x 2.00 1./x 1.7/0.7  C  N  $14.0 0 00000  98196 1os Sachs 504, 505, 2os Piaggio 79- lower
38.60 x 2.0/1.0 x 1.8/.75  L  N  $13.0 0 00000 137690 1os or 2os Piaggio upper ring, 79-later & some 78s
38.70 x 1.50 1./x 1.7/0.7  C  N  $16.0 71.0803.0 4635 Minarelli V1 (US 1979-on and some ’78)
38.80 x 2.0/1.0 x 1.65/.6  L  N  $11.0  4.7470.5140 Demm Smily upper
38.80 x 1.50 x 1.50.7/0.7  C  N  cont..  0000 68.0116.0 Minarelli P4 (export al-cyl, Compact System, Radiale) upper
38.80 x 2.0/1.0 x 1.8/.75  L  N  $11.0  000000
137691 2os Piaggio upper ring
38.80 x 1.50 x 1.50.7/0.7  C  N  $10.0 71.0805.0 4640 Minarelli V1 (US to-1978)
38.80 x 1.50 x 1.50.7/0.7  C  N  cont..  0000 68.0115.0 Minarelli P4 (export iron-cyl, Sport Quadro) both
38.80 x 1.50 x 1.50.7/0.7  C  N  cont.. 
0000
68.0115.0 Minarelli P4 (export al-cyl, Compact System, Radiale) lower
38.80 x 1.50 x 1.50.7/0.7  C  N 
cont..  00.00   137694 2os Piaggio upper ring
38.80 x 1.50 1./x 1.7/0.7  C   I   N/A 00000   22350-65 Aermacchi Harley Davidson M50 1965-66 stroke 42
38.80 x 2.00 1./x 1.7/0.7  C  N  $10.0 00 4.7470.5100 Demm Smily lower
39.00 x 1.00 1./x 1.7/0.7  C  N  $19.0 0.000   26.1060 Morini S5N, S5GS kids off road, both
39.00 x 1.2/1.0 x 1.70 /7  T   I    N/A
   13011.GE2.305a Honda NS50 upper
39.00 x 1.20 x 1.85 /0..7  C   I   $10.0
13011.GE2.305b Honda NS50 lower
39.00 x 1.50 1./x 1.7/0.7  C  N  $10.0 71.0855.7 4650 1os Minarelli  V1, P4, P4 (alum cyl) lower
39.00 x 1.50 1./x 1.7/0.7  C  N  cont..   00.00  26.1044 Morini S5T, S5E, S5ET kids off road, lower
39.00 x 1.50 1./x 1.7/0.7  C   I   $10.0 0000 22351-65 1os Aermacchi Harley Davidson M50 1965-66
39.00 x 2.00 1./x 1.7/0.7  C   I   $12.0 000000   22148 Motobecane (after 06-76) Morini S5R lower
39.00 x 2.00 1./x 1.7/0.7  C  N  $10.0 000000   22148 Motobecane (before 07-75), DiBlasi mini-cycle
39.00 x 2.0/1.0 x 1.8/0.7  L  N  $19.0   00000 26.1003 Morini S5R, S5T alum. cylinder (upper ring)
39.03 x 2.00 1./x 1.7/0.7  C   I   $12.0 00 00  2812200 Jawa 207 1970-83 standard
39.20 x 1.50 1./x 1.7/0.7  C  N  $15.0 71.0855.7 4660 2os Minarelli V1, P4, P4 (al-cyl) lower
39.20 x 1.50 1./x 1.7/0.7  C   I   N/A    00000 22352-65 2os Aermacchi Harley Davidson M50 1965-66
39.25 x 1.2/1.0 x 1.70 /7  T   I   $19.013012.GE2.305a 1os Honda NS50 upper
39.25 x 1.20 x 1.85 /0..7  C   I   $10.0
13012.GE2.305b1os Honda NS50 lower
39.28 x 2.00 x 1.65 /0..7  C   I   $14.0 00 00  2812201 1os Jawa 207 1970-83
39.40 x 1.50 1./x 1.7/0.7  N   N/A    71.0855.7 4670 3os Minarelli V1, P4, P4 (al-cyl) lower
39.40 x 1.50 1./x 1.7/0.7  C   I   N/A   00000 22353-65 3os Aermacchi Harley Davidson M50 1965-66
39.40 x 2.50 1./x 1.7/0.7  C  N   N/A    000 0  0000000 Rizzato Califfo 1978 (Rizzato 119 engine)
39.50 x 1.2/1.0 x 1.70 /7  T   I    N/A   13013.GE2.305a 2os Honda NS50 upper
39.50 x 1.20 x 1.85 /0..7  C   I   $10.013013.GE2.305b 2os Honda NS50 lower
39.50 x 1.70 x 1.60 /0..7  C flat $10.0 00 0000  60817 Solex rings (3) no locating pins
39.53 x 2.00 x 1.65 /0..7  C   I   $19.0 00 00  2812202 2os Jawa 207 1970-83
39.60 x 1.50 1./x 1.7/0.7  C  N  $17.0 71.0855.7 4680 4os Minarelli  V1, P4, P4 (al-cyl) lower
39.80 x 1.50 1./x 1.7/0.7  C  N  $17.0 71.0855.7 4690 5os Minarelli V1, P4, P4 (al-cyl) lower
39.80 x 2.50 1./x 1.7/0.7  C  N 
$10    000 0  0000000 1os Rizzato Califfo 1978 (Rizzato 119 engine)
40.00 x 1.2/1.0 x 1.60 /7  T  N  $14.0 000 00  633086 China 49cc two-strokes upper, most
40.00 x 1.2/1.0 x 1.70 /7  T   I   $14 2W1.11610.0000a Yamaha YSR50 upper, PGO Star 50 upper, others
40.00 x 1.20 x 1.85 /0..7  C   I   $13 2W1.11610.0000b Yamaha YSR50 lower, PGO Star 50 lower, others
40.00 x 1.5/1.3 x 1.80 /7 
$14.0 13011.147.005a Dailim Trac, upper for Honda NC50,PA50,Yamaha QT50
40.00 x 1.50 1./x 1.7/0.7  C  N  $10.0 00 0000  55196 Batavus M48, M56, Trac (not Daelim), Flandria 
Bermuda
40.00 x 1.50 1./x 1.7/0.7  C  N 
cont..  13011.147.005b Honda lower for NC50,PA50, Yamaha QT50 lower
40.00 x 1.50 1./x 1.7/0.7  C  N 
cont..  000000   G7347 Benelli G2, 1965-75 Ward Riverside, Benelli mini-cycles
40.00 x 1.50 1./x 1.7/0.7  C  N 
cont..  00000  26.1044 Morini S5R, S5T alum. cylinder (lower ring)
40.00 x 1.50 1./x 1.7/0.7  C   I   $10.0  00000  551913 Morini MO Gyromat,Convert (early ’70s MO1,MO2)
40.00 x 1.50 1./x 1.7/0.7  C   I 
cont..     0F0.250.0111 Derbi 1986-1989 flat reed, Kreidler Flory
40.00 x 2.00 1./x 1.7/0.7  C  N  $10.0 00   307.021.00 Garelli all 1970’s, 00’s Avanti/Mont (most)
40.00 x 2.00 1./x 1.7/0.7  C  N cont..   00   307.021.00 Casal K177, 2000’s Hero Majestic Pacer
40.00 x 2.0/1.0 x 1.8/0.7  L  N   $11.0 00   310.001.00 Garelli Monza GT upper

40.00 x 2.50 1./x 1.7/0.7  C   I   $14.0 0000000  38315 Peugeot 102, 103 (almost all US models)
40.20 x 1.50 1./x 1.7/0.7  C  N  $22.0 0000   G7347/2 1os Benelli, 1os M Ward, filed down 40.25
40.20 x 2.00 1./x 1.7/0.7  C  N  $15.0 00   308.027.00 1os Garelli
40.25 x 1.00 1./x 1.7/0.7  C  N  $12.0 000..00 633087 1os China 49cc two-stroke scooter
40.25 x 1.5/1.3 x 1.80 /7  T  N   N/A    13021.147.005a 1os Honda NC50, PA50 upper
40.25 x 1.50 1./x 1.7/0.7  C  N  $15.013021.147.005b 1os Honda NC50, PA50 lower, 480511 1os Laura M48
40.30 x 1.50 1./x 1.7/0.7  C  N  $19.0 000000   4641b Minarelli V1HL and V1L lower, filed down 40.5
40.30 x 2.0/1.0 x 1.8/0.7  L  N   N/A    000000   4641a Minarelli V1L upper
40.40 x 1.50 1./x 1.7/0.7  C  N  none    0000   G7347/4 2os Benelli  G2, 2os M Ward and mini-cycles
40.40 x 1.50 1./x 1.7/0.7   I   $$9.0 00 00   26.1045 Morini MO1, MO2, MO4, M1
40.40 x 2.00 1./x 1.7/0.7  C  N  $12.0 0 0  308.028.00 2os Garelli
40.50 x 1.5/1.3 x 1.80 /7  T  N   N/A   13031.147.005a 2os Honda NC50, PA50 upper
40.50 x 1.50 1./x 1.7/0.7  C  N  $12.013031.147.005b 2os Honda NC50, PA50 lower, 2os Laura M48
40.50 x 2.50 1./x 1.7/0.7   I   $12.0 00 0000  33648 1os Peugeot 102, 103 (some, but none in CA)
40.60 x 1.50 1./x 1.7/0.7  C  N  $16.0 00000 G7347/6 3os Benelli, 3os M Ward
40.60 x 1.50 1./x 1.7/0.7  C  N  cont..   71.0860.7 4651b 1os Minarelli V1L lower
40.60 x 1.50 1./x 1.7/0.7  C   I  $12.0 0000 26.1046/6 1os Morini MO1, MO2, MO4, M1
40.60 x 2.00 1./x 1.7/0.7  C  N  $10.0 0 0  308.029.00 3os Garelli
40.60 x 2.0/1.0 x 1.65/.6  L  N  $15.071.0860.7 4651a 1os Minarelli V1L upper
40.75 x 1.5/1.3 x 1.80 /7  T  N   N/A    13041.147.005a 3os Honda NC50, PA50 upper
40.75 x 1.50 1./x 1.7/0.7  C  N   N/A    13041.147.005b 3os Honda NC50, PA50 lower
40.80 x 1.50 1./x 1.7/0.7  C   I   $12.0 000   26.1046/8 2os Morini MO1, MO2, MO4, M1
40.80 x 1.50 1./x 1.7/0.7  C  N  $9.0 71.0860.7 4661b 2os Minarelli V1L lower
40.80 x 2.0/1.0 x 1.65/.6  L  N   N/A   71.0860.7 4661a 2os Minarelli V1L upper
40.80 x 2.00 1./x 1.7/0.7  C  N  $10.0  00  308.030.00 4os Garelli 

41.00 x 1.2/1.0 x 1.90 /7  T   I   $14   
13010.GJ5.015a Honda TG50, NN50 Gyro upper
41.00 x 1.2/1.0 x 1.90 /7  C   I   N/A    13010.GJ5.015b Honda TG50, NN50 Gyro lower
41.00 x 1.5/1.3 x 1.80 /7  T   I   $14.0 0  12140-16B10 Suzuki FY50, FZ50, FA50 upper
41.00 x 1.50 1./x 1.7/0.7  C  N  $10.0 0000000  00000 Minarelli V1 Industriale 53cc stroke 42

41.40 x 1.50 1./x 1.7/0.7  C   I   $12.0 0000000  00000 Unknown only one
42.00 x 1.50 1./x 1.7/0.7  C  N   N/A    0 00000  00000 Minarelli V1 Carrabela 58cc stroke 42
42.00 x 2.00 1./x 1.7/0.7  C  N   N/A  0000000  00000 Puch DS60
42.00 x 1.50 1./x 1.7/0.7  C flat
$40/set    E660-00-50 Indian 4-stroke ring set comp(2) oil(1)
42.25 x 1.50 1./x 1.7/0.7  C flat
$40/set    E660-10-50 1os Indian 4-stroke set comp(2) oil(1)
42.50 x 1.50 1./x 1.7/0.7  C flat  N/A     
     E660-20-50 2os Indian 4-stroke set comp(2) oil(1)
42.75 x 1.50 1./x 1.7/0.7  C  N  $12.0 0000000  00000 big bore kit appr 60cc only two
43.00 x 1.50 1./x 1.7/0.7  C  N  $12.0 0000000  4635HP big bore kit appr 60cc only 3
43.00 x 2.0/1.0 x 1.65/.6  L   N  $16.0 0000000  00000 big bore kit appr 60cc only one
43.50 x 1.50 1./x 1.7/0.7  C  N  $10.0 0000000  00000 big bore kit appr 60cc

44.00 x 1.50 1./x 1.7/0.7  C  N  $10.0 0000000  G-591 Benelli Dynamo 65 59cc stroke 39
44.00 x 1.50 1./x 1.7/0.7  C  N 
cont..  00000    MF-554 big bore kit Peugeot 103 59cc
44.00 x 1.50 1./x 1.7/0.7  C   I    N/A    00000 22350-67 Aermacchi Harley Davidson M65 1967-72 64cc stroke 42
44.20 x 1.50 1./x 1.7/0.7  C   I    N/A    00000 22351-67 1os Aermacchi Harley Davidson M65 1967-72 64.5
44.40 x 1.50 1./x 1.7/0.7  C   I    N/A    00000 22352-67 2os Aermacchi Harley Davidson M65 1967-72 65cc

45.00 x 1.50 1./x 1.7/0.7  C  N   N/A    0 0000. 71.8187 Minarelli P4-70, P6-70 67cc
45.20 x 1.50 1./x 1.7/0.7  C  N   N/A    0 0000. 71.8187 1os Minarelli P4-70, P6-70 67cc
45.40 x 1.50 1./x 1.7/0.7  C  N   N/A    0 0000. 71.8187 2os Minarelli P4-70, P6-70 67cc  

 

 


Ring Information

 

Pinned or Not Pinned: Most moped piston rings are two-stroke style, where there are pins in the ring grooves of the piston that keep the rings from rotating around. Two stroke cylinders have holes or ports that the ring ends can snag on. So two stroke rings are pinned to the piston. Four stroke cylinders do not have any holes, so four stroke rings are not pinned. Knowing about those pins is important when installing.    

Getting the right rings: If your model is not in the applications, then you must measure the bore and the ring thickness. A calipers is the best tool to measure the bore (ring diameter) and ring thickness. Sometimes your rings might not be original, for many reasons. The piston might be aftermarket with thinner rings. The cylinder might be bored out to an oversize bore. Some mopeds came with more than one piston size or ring style.

Break a ring, how not to: Two stroke pistons have little pins (stumps, bumps) in the piston ring grooves that prevent the rings from rotating. Knowing where each ring locating pin is, and aligning the ring gap over the pin during cylinder installation, is the key to not breaking the ring. 

Measuring wear: A new piston ring is a the best tool to measure how worn a cylinder is. Conversely, a new cylinder is the best tool to measure how worn a ring is. To measure the wear of a ring, you need a perfectly round cylinder of a precisely known bore. A worn cylinder that has not been honed will still have it’s original new bore at the very top, above where the rings rub at. A new ring in a new cylinder should have a very small end gap of .004 to .008″. A worn but still OK cylinder with a new ring will have a gap of .0010 to .018″. A worn cylinder and ring both will have an end gap of over .020″(.5mm). A badly worn cylinder and/or ring will have a huge gap, over .030″(.75mm). You measure ring gap with a feeler gauge.

Classifying Jawa Rings

Classifying Piston Rings

Classifying rings: Rings get mixed up and are difficult to tell the size, unless a perfectly round cylinder of an appropriate size is available to place the ring in. If you try to squeeze a piston ring into a circle with just fingers, it inevitably becomes a very rounded polygon, or at best an ellipse. So the measurement becomes inaccurate. At right is how Myrons Mopeds’s Jawa piston rings were classified, using a piece of aluminum tubing with a tight fitting piston inside it to hold the tube round, and the test ring square. From top to bottom, 39.03 x 2.0, 39.28 x 2.0, 39.53 x 2.0, 39.78 x 2.0mm. Each ring increases in diameter by 0.25mm, so the circumference increases by Pi times that, or about 0.8mm. Here the inside of an old fishing pole tube is 39.78mm, perfect for the 3rd oversize 39.78 ring, on the bottom, with a gap of almost zero. Each gap is 0.8mm more because each ring is 0.25mm less diameter. It is important that the piston and ring fit the cylinder properly.   

Filing down: To make a ring slightly smaller, one of the two ring ends can be filed down, while preserving the shape. To reduce the size (diameter) by 0.20 mm, the end must be filed down by pi times that, 0.63 mm. When a filed down ring is installed in a cylinder smaller than it was designed for, two things change. The tension is greater, and the shape is slightly non-circular. So filed rings need a longer break-in period, to wear down the higher places. With 38 to 41 mm rings, the size can be reduced by 0.2mm with about 30 minutes of break-in, and by 0.5mm with about 2 hours of break-in. After break-in the rings have a mirror polish all around.

Why is the width not specified? Because the inner side of the ring does not touch anything. The ring has spring tension pushing it outwards, keeping the bottom (inner) surface from touching the bottom of the ring groove. So the ring width can be any amount, from about half the groove depth, to the groove depth. The exact ring width is not important. Exact ring height and diameter are important. 

 

 


Pistons

July 13, 2019


50cc pistons for sale here are listed by “pin”, the wrist pin thickness, and “upper”, the distance from the pin edge to the top edge. Pin ranges from 10 to 14mm. Upper ranges from 13 to 23mm.

Pistons in the same section have the same upper and pin dimensions, and so can potentially interchange, if the bore and maybe other things are the same. That is why pistons are listed by size rather than name.

For example, an oversize Peugeot 103 piston 40.5mm is perfect for a worn 40.4mm Morini MO1, after honing. They are both 12 pin and 16 upper, in the 12-16 section.

Look up or measure your piston’s pin size and upper length,
then scroll to that “pin-upper” section.

pin-upper  
  12-18
Batavus with Laura M48 engine
  12-17 Benelli 1965-1980
  12-23 Casal K177, others
  10-19 Columbia with Solo 255 engine
  12-22 Columbia with Sachs 505 engine

  12-18 Daelim DP50, DK50 engine
  12-22 Demm Smily

  12-17 Derbi Variant, TT, RD50 1974-1986
  12-18 Derbi Variant Sport 1986-90
  14-24 Flandria Bermuda
  12-18 Garelli Eureka, Noi, Gulp, VIP
  12-22 Garelli Monza GT

  12-16 Hero Majestic mid-90’s
  10-20 Honda NC50, NA50, NU50, PA50
  12-19 Honda NS50F
  13-13 Indian AMI50 with PC50K1 re-make engine
  14-18 Jawa Babetta 207 1970-83
  12-16 Kawasaki AR50

  12-20 Kinetic TFR with Piaggio re-make engine
  12-19 Kreidler MP9, MP19
  12-18 Laura M48, M56 engine

  12-21 Minarelli V1L, V1HL engine
  12-22 Minarelli V1, V1H engine
  12-16 Morini MO1 MO2 MO4 M1 M101 w/alum fins
  12-19 Morini MO1, MO2, M1 with iron cylinder fins

  12-22 Morini S5K, S5K2, S5R, S5T engine
  13-15 Motobecane 40, 50 with AV7 engine
  10-19 Odyssey with Solo 254, 255 engine

  12-16 Peugeot 102, 103 series
  10-18 Puch MS50, others 50’s-60’s
  12-17 Puch Maxi, others 1969-86
  12-15 Rizzato 119 engine on Califfo
  12-22 Sachs 504, 505 engine
  10-18 Sears Allstate moped and early Puch

  10-19 Solo 236, 237, 254, 255 engine
  12-21 Suzuki FA50 Shuttle, FY50, FZ50
  10-18 Tomos A3 engine 1974-91
  12-17 Tomos A35 engine 1992-2006 (cyl says A5)
  12-17 Tomos A55 engine 2002-18 (case says A52)

  12-18 Trac 1981-96 with M56-remake engine
  10-19 TYM M48-remake engine on Angel, Speed Bird
  12-20 Vespa (Piaggio) Ciao, Bravo, Grande, Si
  10-21 Vespa (Piaggio) Ciao, Si (1990’s Euro)
  10-20 Yamaha QT50 Yamahopper, PW50

 

updated 2021-03

Notes:
Piston actual diameter is measured at skirt (bottom), where it is largest. 
All new pistons come with new rings, clips and pin, unless noted.
gap GN grano normale means side pin gap style (aka FG foro grano)                        
gap GI  grano interno means center pin gap style  (see photos above)

Meanings:  “size” = cylinder bore                
ring c1.5n means common (rectangular), 1.5mm thick,  normal gap style
ring c1.5i  means common (rectangular), 1.5mm thick,  internal gap style
ring t1.5n means trapezoidal (slanted top) 1.5mm outer, normal gap style

ring t1.5i 
means trapezoidal (slanted top) 1.5mm outer, internal gap style
ring L1.5  means “L“-shaped (aka Dykes), 1.5mm outer, L-ring gap style
“x” means that part of the number is unknown

 


Tomos A3 piston

Tom. A3

10-18 pistons for 1974-91 Tomos A3, 50’s-60’s Puch and Tomos

pin up  lo bore M#   skirt    ring1   ring2  price  maker    38.0 bore, 10 pin, 18 upper
10-18-24-38.00-0  37.94  c2.0n  c2.0n  n.a.  xxxxx  2074??  Tomos A3 1.0hp
10-18-24-38.00-0  37.94  c2.0n  c2.0n n.a.  55 tall, 52 at edge = 24+10+18

10-18-21-38.00-0  37.94  c2.0n  c2.0n  n.a.  xxxxx  207407  Tomos A3 1.5hp
10-18-21-38.00-0  37.94  c2.0n  c2.0n  n.a. 52 tall, 49 at edge = 21+10+18

Tomos A3 and Sears Allstate

10-18-19-38.00-0  37.94  c2.0n  c2.0n  $50   xxxxx  207403  Tomos A3 2.0hp
10-18-19-38.00-0  37.94  c2.0n  c2.0n  $00   50 tall, 47 at edge = 19+10+18
10-18-19-38.00-1  37.95  c1.5n  c1.5n  $60   generic  for Tomos A3
10-18-18-38.00-0  37.95  c2.0n  c2.0n  n.a.  generic  for Tomos A3
10-18-19-38.00-2  37.9x  c2.0n  c2.0n  n.a.  Mahle  0501.1006.2 Sears Allstate
pin up  lo bore M#   skirt    ring1   ring2  price  maker    38.5 bore, 10 pin, 18 upper
10-18-19-38.50-0  38.45  c2.0n  c2.0n  n.a.  Mahle  202420 Tomos A3 oversize

.


Tomos+Solo

10-19 pistons for 1976-80 Solo on Odyssey,Columbia, ’77-84 TYM Angel 

pin up  lo bore M#    skirt   ring1  ring2   price  maker    38.0 bore, 10 pin, 19 upper
10-19-22-38.00-N  37.9x  c1.5n  c1.5n  n.a.  Mahle    2200593 Solo piston “N”
10-19-22-38.00-U  37.9x  c1.5n  c1.5n  n.a.  Mahle    2200600 Solo piston “U”
pin up  lo bore M#    skirt   ring1  ring2   price  maker    40.0 bore, 10 pin, 19 upper
10-19-15-40.00-0  39.92  c1.5n  c1.5n  n.a.  generic  original  Angel/Speed Bird

Angel and Batavus pistons

Angel+Batavus

A Batavus piston (12 x 33 mm pin) can substitute for an Angel piston (10 x 33 pin), if the piston pin needle bearing is changed. The 10x14x13 needle bearing (with 2mm rollers) needs to be 12x14x13. But there are none that thin (1mm rollers). So a bronze bushing 12x14x13 must be used instead of a needle bearing, like one from a Puch.  There are already oil holes in the Angel rod. Those holes need to extend through the bronze bushing to oil the pin.

 


Honda NC50 and PA50 piston new

NC50

20mm upper (10mm pin) Yamaha QT50 & PW50

QT50

10-20 pistons for 1977-83 Honda NC50 PA50, Yamaha QT50 PW50

pin up  lo bore M#    skirt  ring1  ring2   maker  price    40.0 bore, 10 pin, 20.5 upper
10-20-18-40.00-0  39.95  t1.5n  c1.5n  Honda   n.a.  13101.147.000  Honda NC50
10-20-18-40.00-0  39.95  t1.5n  c1.5n  Honda   n.a.  Honda PA50 (has decomp cut)
10-20-18-40.00-1  39.95  t1.5n  c1.5n  generic  $43  re-make Honda NC50, PA50
10-20-17-40.00-0  39.9x  t1.5n  c1.5n  Yamaha  n.a.  3L5.11630.00.00  Yamaha QT50, PW50

 

21mm upper, 10 pin, Vespa Euro models

Vespa

21mm upper, 10mm pin Chinese scooters

Eton

10-21 pistons for 1990’s Vespa (Euro), China scooters

pin up  lo bore M#    skirt  ring1  ring2   maker  price    38.2 bore, 10 pin, 21 upper
10-21-17-38.20-0  38.13  L2.0n  c1.5n  Meteor  $60  Vespa 84-85 Ciao & Si, Euro models
pin up  lo bore M#    skirt  ring1  ring2   maker  price    40.0 bore, 10 pin, 21 upper
10-21-18-40.00-0  39.9x  t1.2n  t1.2n  generic  $60  632964 E-Ton 50cc 2-stroke scooter
pin up  lo bore M#    skirt  ring1  ring2   maker  price    40.25 bore, 10 pin, 21 upper
10-21-18-40.25-0  40.1x  t1.2n  t1.2n  generic  $60  632965 1os E-Ton 50cc 2-stroke scooter


Rizzato

12-15 pistons for Rizzato 119 engine on Califfo, Atala

pin up  lo bore M#    skirt  ring1  ring2   maker  price    39.4 bore, 12 pin, 15 upper
12-15-23-39.40-0  39.33  c2.5n  c2.5n  generic  $35  original  no rings, none available
pin up  lo bore M#    skirt  ring1  ring2   maker  price    39.8 bore, 12 pin, 15 upper
12-15-23-39.80-0  39.73  c2.5n  c2.5n  generic  N/A  original  1os Rizzato Califfo

This is an unusual design from the 1950’s, with the highest wrist pin. That allows transfer flow through the lower part of the piston, instead of around the sides completely. The top crown of the piston is a normal shallow dome, but with three equal large “bites” taken out of it. 


16mm upper height pistons Peugeot left and Morini right

Peugeot+Morini

12-16 pistons for ’70’s Peugeot 103, 102, others, ’90’s Hero
and ’72-80 Morini MO, MO1, MO2, M1, M101 with aluminum cylinder fins

pin up  lo bore M#    skirt  ring1  ring2   maker  price    39.0 bore, 12 pin, 16 upper
12-16-18-39.00-0  38.95  t1.2n  t1.2n generic  n.a.  13001.1074  Kawasaki AR50
pin up  lo bore M#    skirt  ring1  ring2   maker  price    40.0 bore, 12 pin, 16 upper
12-16-17-39.91-A  39.88  c2.5i   c2.5i Peugeot $70  69707 Peugeot Sort A
12-16-17-39.92-B  39.89  c2.5i   c2.5i Peugeot $70  69708 Peugeot Sort B

16mm upper, 12 pin, Peugeot

Peugeot

12-16-17-39.93-C  39.90  c2.5i   c2.5i Peugeot $70  69709 Peugeot Sort C (=AA)
12-16-17-39.94-D  39.91  c2.5i   c2.5i Peugeot n.a.  69710 Peugeot Sort D (=BB)
12-16-17-39.94-0  39.91  c2.5i   c2.5i GOL       $60  replica Peugeot Sort D (=BB)
12-16-17-40.00-0  39.92  c1.5i   c1.5i Asso 00 n.a.  23-01xx Morini early MO1 cut=3
12-16-17-40.00-1  39.9x  c2.0n c2.0n generic  n.a.  original Hero Pacer, Panther
12-16-17-39.95-E  39.92  c2.5i   c2.5i Peugeot $70  69711 Peugeot Sort E (=CC)
12-16-17-39.96-F  39.93  c2.5i   c2.5i Peugeot $70  69712 Peugeot Sort F (=DD)

1995 Hero Panther

1995 Hero Panther

12-16-17-39.96-0   39.93  c1.5i   c2.5i generic  $70  re-make MMI MF553-F for Peugeot
12-16-17-39.97-G  39.94  c2.5i   c2.5i Peugeot $70  69713 Peugeot Sort G (=EE)
12-16-17-39.98-H  39.95  c2.5i   c2.5i Peugeot $70  69714 Peugeot Sort H (=FF)
12-16-17-39.98-0  39.95  c2.5i   c1.5i generic  $70  re-make MMI MF553-C for Peugeot
12-16-17-39.99-I   39.96  c2.5i   c2.5i Peugeot n.a.  69715 Peugeot Sort I (=GG)
12-16-17-40.00-J   39.97  c2.5i   c2.5i Peugeot n.a.  69715a Peugeot Sort HH
12-16-17-40.01-ii  39.98  c2.5i   c2.5i Peugeot n.a.  69715b Peugeot Sort II

pin up  lo bore M#    skirt  ring1 ring2  maker  price    40.4 bore, 12 pin, 16 upper
12-16-17-40.40-L  40.33  L2.0   c1.5i Asso      n.a. 23.01?? Morini MO4 cut=3 ASSO 1929MO4
12-16-17-40.40-0  40.35  c1.5i  c1.5i Asso      $70 23.0125 Morini MO1,2 cut=5 ASSO.W 2351
12-16-17-40.40-0  40.32  c1.5i  c1.5i Asso      n.a. 23.0125 Morini MO1,2 cut=3   ASSO 1929
12-16-17-40.40-0  40.35  c1.5i  c1.5i generic  $60 23.0125 Morini MO1,2 cut=3  says nothing
12-16-17-40.40-0  40.32  c1.5i  c1.5i Asso      n.a. 23.0125 Morini MO1,2 cut=3 ASSO.W 2352
12-16-17-40.40-1  40.32  c1.5i  c1.5i Asso      n.a. 23.0134 Morini M1  cut=0 ASSO W 1929M1

Morini pistons

pin up  lo bore M#    skirt  ring1 ring2  maker  price    40.5 bore, 12 pin, 16 upper
12-16-17-40.47-K  40.44  c2.5i  c2.5i Peugeot $60  69716  1os Peugeot Sort K
12-16-17-40.48-L   40.45  c2.5i  c2.5i Peugeot $60  69717  1os Peugeot Sort L
12-16-17-40.49-M  40.46  c2.5i  c2.5i Peugeot $60  69718  1os Peugeot Sort M
12-16-17-40.50-N  40.47  c2.5i  c2.5i Peugeot $60  69719  1os Peugeot Sort N
12-16-17-40.51-P   40.48  c2.5i  c2.5i Peugeot $60  69720  1os Peugeot Sort P
12-16-17-40.52-Q  40.49  c2.5i  c2.5i Peugeot $60  69721  1os Peugeot Sort Q
pin up  lo bore M#    skirt  ring1 ring2  maker  price    40.6 bore, 12 pin, 16 upper
12-16-17-40.60-0  40.53  c1.5i  c1.5i Asso     $72 23.0126/6 1os Morini MO1,2 cut=3 ASSO 1929
12-16-17-40.60-1  40.5x  c1.5i  c1.5i Asso     n.a. 23.0135/6 1os Morini M1 cut=0 ASSO W 1929M1
pin up  lo bore M#    skirt  ring1 ring2  maker  price    40.8 bore, 12 pin, 16 upper
12-16-17-40.80-0  40.72  c1.5i  c1.5i Asso     $72 23.0126/8 2os Morini MO1,2 cut=3 ASSO 1929
12-16-17-40.80-1  40.7x  c1.5i  c1.5i Asso     n.a. 23.0135/8 2os Morini M1 cut=0 ASSO W 1929M1
pin up  lo bore M#    skirt  ring1 ring2  maker  price    41.0 bore, 12 pin, 16 upper
12-16-17-41.00-0  40.90  c1.5i  c1.5i generic $74 23.0126/0 3os Morini MO1,2 cut=3 says nothing

Morini MO1 and MO2 pistons have a cut-out on the bottom intake side. It can be different heights 0, 3 or 5 mm. That’s what “cut=3” means. Inside the piston is an ID mark, such as “ASSO 1929”. This can tell the piston type but not the size. 

Peugeot 1980 tiny

Peugeot 103 pistons have slightly different sizes.

Peugeot 103 pistons have slightly different sizes, aka “sorts”.
Left of the red line are the “standard” 40.0mm sorts A to II (39.88-39.98).
Right of the red line are the “oversize” 40.5mm sorts K to Q (40.45-40.50).
Upper half are chrome bore cylinders, pre-1979 with single letter sorts A to Q.
Lower half are nikasil bore cylinders, 1979-on with double letter sorts AA to II.

Peugeot 103 moped pistons are a very old design that has been in use at least since the 1950’s. The rings are thick, 2.5mm, like most old rings were. Peugeot 103 cylinders are all aluminum with a chrome plated (pre-1979) or nikasil plated (1979-on) cylinder wall. They expand along with the aluminum piston as they get hotter. Unlike a steel sleeve cylinder that fits slightly loose, when cold, and wiggles a tiny bit, these should be a light sliding fit, where the piston, without rings, pushes through by hand but does not fall through by it’s own weight. When the piston fit is too loose, it makes a tinkle sound when idling, and produces less torque. When it’s too tight, it simply won’t move easy, or at all, and when hot it will smear (melt off) the hot exhaust side and stick (seize). The procedure for “fitting” a Peugeot piston requires a flat stone cylinder hone (not a ball hone) for first making the cylinder wall flat by removing any high spots, and a Dremmel high speed rotary cutting tool for removing burrs from the edges of the ports, and a small round file for removing burrs and high spots from the piston, especially around the wrist pin holes. Sometimes just the act of pushing the wrist pin in and out will raise the corner edge and make the piston fit tighter. The bare piston is pushed into the cylinder in different ways. The high spots are located, by feel and sometimes vision, and removed. When all high spots are removed, and the piston still does not fall through under it’s own weight, then the fit is perfect.  Worn cylinders need slightly bigger pistons. So a worn “C” cylinder might need a D, E, or F piston. Badly worn or “gouged” cylinders need to be replaced (unless the gouges are lower than the exhaust port). Peugeot has made plenty of “oversize” (40.5mm instead of 40.0mm) pistons. But there are no 40.5 cylinders in California, only 40.0mm. That’s why Myrons Mopeds has 40.5 pistons but no cylinders. Too bad it’s expensive to bore out and re-plate a nikasil cylinder. It is an option, made possible by the half millimeter bigger pistons available.

 


Tomos A55

12-17  pistons for ’69-86 Puch, 91-18 Tomos, 74-86 Derbi, 65-80 Benelli

pin up  lo bore M#  skirt  ring1 ring2  maker  price    36.5 bore, 12 pin, 17 upper
12-17-18-36.50-0 36.43 c1.5n c1.5n Vertex  $55 229803  Tomos MC36 36cc off road
pin up  lo bore M#  skirt  ring1 ring2  maker  price    38.0 bore, 12 pin, 17 upper
12-17-18-38.00-0 37.93 c2.0n c2.0n generic $40 406300 Puch Step II, made small
12-17-18-38.00-A 37.95 c1.5n c1.5n generic n.a. 409000   Tomos A35 iron cyl, has windows

17mm upper, 12mm pin, Tomos A35 1992-06

Tomos A35

12-17-18-38.00-B 37.95 c1.5n c1.5n Vertex  $65 223747   Tomos A35 has windows on int. side
12-17-19-38.00-0 37.91 c2.0n c2.0n generic $30 406300 Puch early 2000’s, way small
12-17-20-38.00-0 37.96 c1.5n c1.5n generic $55 thereal1  Puch,  well-made in Taiwan
12-17-21-37.99-0 37.95 c2.0n none  Mahle   $72 original                Puch ’84 alu sort C  38 C 1734
12-17-21-37.98-1 37.95 c2.0n c2.0n Mahle   n.a. 349.110.0069/21 Puch alu cyl sort 1   38 1 101
12-17-21-37.99-2 37.96 c2.0n c2.0n Mahle   n.a. 349.110.0069/22 Puch alu sort 2   38 2 1019
12-17-21-38.00-3 37.97 c2.0n c2.0n Mahle   n.a. 349.110.0069/23 Puch alu sort 3   38 3 1019
12-17-21-38.01-4 37.98 c2.0n c2.0n Mahle   $65 349.110.0069/24 Puch alu sort 4   38 4 1019
12-17-21-38.02-5 37.99 c2.0n c2.0n Mahle   $75 349.110.0069/25 Puch alu sort 5   38 5 1019

17mm upper (12 pin) Puch

Puch

12-17-21-37.98-A 37.95 t1.5n  t1.5n Vertex  n.a. 233709   Tomos A55 alu cyl to-’06 trap. rings
12-17-21-37.98-B 37.95 c1.5n c1.5n Vertex  $65 233709   Tomos A55 alu cyl ’07-on 14140 37.98 
12-17-22-38.00-1 37.95 c2.0n c2.0n Mahle   n.a. 350.310.0069/03 Puch HT sort 11 38 1 1116
12-17-22-38.01-2 37.96 c2.0n c2.0n Mahle   n.a. 350.310.0069/04 Puch HT sort 22 38 2 1116
12-17-23-38.00-C 37.94 c2.0n c2.0n GOL      $60 0037A-C Puch, made in Italy by GOL
12-17-23-38.00-D 37.95 c2.0n c2.0n GOL     $60 0037A-D Puch, made in Italy by GOL
12-17-23-38.00-0 37.95 L2.0   c1.5n Mahle   $70 000.802.5090  Derbi 1976-86     says B9
12-17-23-38.00-1 37.95 L2.0n c2.0n Mahle   n.a. 349.210.5069/11 Puch HT  11 38.0 11 1593a
12-17-23-38.01-2 37.96 L2.0n c2.0n Mahle   n.a. 349.210.5069/22 Puch HT  22 38.0 22 1593a
12-17-23-38.02-3 37.97 L2.0n c2.0n Mahle   $65 349.210.5069/33 Puch HT  33 38.0 33 1593a

17mm upper (12 pin) Derbi Variant pre-'87

Derbi-’86

pin up  lo bore M#  skirt  ring1 ring2  maker  price    38.25 bore, 12 pin, 17 uppe
12-17-21-38.25-0 38.17 c2.0n c2.0n generic $50
203.200 1os Puch Step Two 

12-17-20-38.25-0 38.18 L2.0n c1.5n Mahle   $40
000.802.5091 1os Derbi 76-86 0.25 B or 0.25 C 
12-17-20-38.25-ll 38.18 L2.0n L2.0n Mahle   $40 000.802.5091 1os same but both L-rings!

12-17-20-38.25-0 38.18 L2.0n c1.5n Mahle   $35 000.802.5091 1os Derbi 76-86 38.205 JG 0.045
12-17-23-38.25-1 38.19 L2.0n c2.0n Mahle   n.a. 349.310.4669/03 1os Puch 11 38.25 11 1593a
12-17-23-38.25-2 38.20 L2.0n c2.0n Mahle   n.a. 349.310.4669/04 1os Puch 22 38.25 22 1593a
pin up  lo bore M#  skirt  ring1 ring2  maker  price    38.4 bore, 12 pin, 17 upper
12-17-20-38.40-0 38.3? L2.0n c1.5n Mahle   n.a. 000.802.5092 2os Derbi 1976-1986
pin up  lo bore M#  skirt  ring1 ring2  maker  price    38.5 bore, 12 pin, 17 upper
12-17-21-38.50-0 38.4x c1.5n c1.5n Vertex  n.a. 227334 1os Tomos A35
12-17-21-38.50-1 38.4x c1.5n c1.5n generic $60 409001 1os Tomos A35
pin up  lo bore M#  skirt  ring1 ring2  maker  price    38.7 bore, 12 pin, 17 upper
12-17-20-38.70-0 38.6x L2.0n c1.5n Mahle   n.a. 000.802.5093 3os Derbi 1976-1986
pin up  lo bore M#  skirt  ring1 ring2  maker  price    38.9 bore, 12 pin, 17 upper
12-17-20-38.90-0 38.8x L2.0n c1.5n Mahle   n.a. 000.802.5094 4os Derbi 1976-1986

17mm upper, 12 pin, Benelli

Benelli

pin up  lo bore M#  skirt  ring1 ring2  maker  price    40.0 bore, 12 pin, 17 upper
12-17-18-40.00-0 39.9x c1.5n c1.5n Asso     n.a. 70.06.04.00  Benelli ’65-80 #G7346
12-17-18-40.00-1 39.95 c1.5n c1.5n GOL      $65 70.06.04.00a Benelli ’65-80
12-17-19-40.00-0 39.94 t1.5n  t1.5n Yamaha $60 original  Yamaha model?  complete
pin up  lo bore M#  skirt  ring1 ring2  maker  price    40.2 bore, 12 pin, 17 upper
12-17-18-40.20-0 40.1x c1.5n c1.5n Asso     n.a. 70.06.04.02 1os Benelli ’65-80 #G7346/2
pin up  lo bore M#  skirt  ring1 ring2  maker  price    40.25 bore, 12 pin, 17 upper
12-17-19-40.25-0 40.22 t1.5n  t1.5n Yamaha $30 original  1os Yamaha model?  without rings
pin up  lo bore M#  skirt  ring1 ring2  maker  price    40.4 bore, 12 pin, 17 upper
12-17-18-40.40-0 40.3x c1.5n c1.5n Asso     n.a. 70.06.04.04 2os Benelli ’65-80 #G7346/4

 

18mm upper, 12 pin Daelim (Trac)

Daelim

12-18  pistons for  86-89 Derbi, 70-90 Garelli, 72-80 Batavus, 81-89 Trac

pin up  lo bore M#  skirt  ring1 ring2  maker  price    40.0 bore, 12 pin, 18 upper
12-18-14-40.00-T 39.9x t1.5n  t1.5n generic n.a. ?????? Daelim (Trac) original (trap. rings)
12-18-14-40.00-0 39.95 c1.5n c1.5n Mahle  n.a. 480580 Batavus M48 original says 39.95
12-18-14-40.00-1 39.92 c1.5n c1.5n generic $70 408211 Daelim (Trac) replica (rect. rings)
12-18-14-39.99-A 39.96 c1.5n c1.5n Mahle  n.a. 80016 Batavus/Trac M56 original says A
12-18-14-40.00-B 39.97 c1.5n c1.5n Mahle  n.a. 80017 Batavus/Trac M56 original says B
12-18-14-40.01-C 39.98 c1.5n c1.5n Mahle  n.a. 80018  Batavus/Trac M56 original says C

Batavus

12-18-14-40.02-D 39.99 c1.5n c1.5n Mahle  n.a. 80019  Batavus/Trac M56 original says D
12-18-14-40.03-E 40.00 c1.5n c1.5n Mahle  n.a. 80020  Batavus/Trac M56 original says E
12-18-14-40.00-F  40.0x c1.5n c1.5n Mahle  n.a. ??????  Batavus/Trac M56 original says F
12-18-16-40.00-0 39.93 c2.0n c2.0n generic $60 Treats Garelli/Batavus aftermarket
12-18-16-40.00-1 39.95 c2.0n c2.0n GOL     $60 0037 Garelli/Batavus aftermarket
12-18-16-40.00-0 39.9x c2.0n c2.0n Asso    n.a. 200001.2.150 Garelli iron cylinder 20,30mph
12-18-?? -40.00-0 39.9x c2.0n c2.0n Asso    n.a. 205058.2.150 flat top, Garelli al cyl 20,25mph
12-18-?? -40.00-0 39.9x c2.0n c2.0n Asso    n.a. 205088.2.150 flat top, Garelli alu cyl 30mph
12-18-17-40.00-0 39.9x c2.0n c2.0n Asso    n.a. 205053.2.150 Garelli iron cylinder 25mph

Mahle12-18-19-39.97-A 39.945c1.5i  c1.5i Mahle  n.a. 0F0.250.0091/A Derbi ’86-89 flat reed, sort A
12-18-19-39.97-B 39.950c1.5i  c1.5i Mahle  n.a. 0F0.250.0091/B Derbi ’86-89 flat reed, sort B
12-18-19-39.98-C 39.955c1.5i  c1.5i Mahle  n.a. 0F0.250.0091/C Derbi ’86-89 flat reed, sort C
12-18-19-39.98-D 39.960c1.5i  c1.5i Mahle  n.a. 0F0.250.0091/D Derbi ’86-89 flat reed, sort D
12-18-19-39.99-E 39.965c1.5i  c1.5i Mahle  n.a. 0F0.250.0091/E Derbi ’86-89 flat reed, sort E

18mm upper, 12 pin, Garelli

Garelli

pin up  lo bore M#  skirt  ring1 ring2  maker  price    40.2 bore, 12 pin, 18 upper
12-18-16-40.20-0 40.1x c2.0n c2.0n Asso    n.a. 200001.2.151  1os Garelli iron cylinder 20, 30mph
12-18-17-40.20-0 40.1x c2.0n c2.0n Asso    n.a. 205053.2.151 1os Garelli iron cylinder 25mph
pin up  lo bore M#  skirt  ring1 ring2  maker  price    40.25 bore, 12 pin, 18 upper
12-18-14-40.25-0 40.20 c1.5n c1.5n Mahle  $75 480581 1os Batavus with Laura M48 engine
pin up  lo bore M#  skirt  ring1 ring2  maker  price    40.40 bore, 12 pin, 18 upper
12-18-16-40.40-0 40.3x c2.0n c2.0n Asso    n.a. 200001.2.152 2os Garelli iron cylinder 20, 30mph
12-18-17-40.40-0 40.3x c2.0n c2.0n Asso    n.a. 205053.2.152 2os Garelli iron cylinder 25mph
12-18-17-40.40-0 40.33 c2.0n c2.0n GOL    $55 534404 2os Garelli (made in Italy)

pin up  lo bore M#  skirt  ring1 ring2  maker  price    40.60 bore, 12 pin, 18 upperAsso
12-18-16-40.60-0 40.5x c2.0n c2.0n Asso    n.a. 200001.2.153 3os Garelli iron cylinder 20, 30mph
12-18-17-40.60-0 40.5x c2.0n c2.0n Asso    n.a. 205053.2.153 3os Garelli iron cylinder 25mph
pin up  lo bore M#  skirt  ring1 ring2  maker  price    40.80 bore, 12 pin, 18 upper
12-18-16-40.80-0 40.7x c2.0n c2.0n Asso    n.a. 200001.2.154 4os Garelli iron cylinder 20, 30mph
12-18-17-40.80-0 40.7x c2.0n c2.0n Asso    n.a. 205053.2.154 4os Garelli iron cylinder 25mph

Garelli pistons

Garelli 4th oversize 40.8mm piston, made by Asso, says “40.8”. You can see it’s bigger. Middle, Garelli standard 40.0mm piston, made by Asso, says “40” and “S”. The “S” means scoria, Italian for exhaust. Right, Garelli standard 40.0mm piston, aftermarket. All three are oriented with the exhaust side down, like in the engine.

 


Kreidler

12-19  pistons for  1970’s Kreidler Flory, 1990 Honda NS50
and ’75-80 Morini MO, MO1, MO2, M1 with all-iron cylinder fins

pin up  lo bore M#  skirt  ring1 ring2  maker  price    39.0 bore, 12 pin, 19 upper
12-19-16-39.00-0 38.94 t1.2n c1.2n  generic none 13101-GE2-305 Honda NS50 ’90
pin up  lo bore M#  skirt  ring1 ring2  maker  price    39.25 bore, 12 pin, 19 upper
12-19-16-39.25-0 39.19 t1.2n c1.2n  generic none 13102-GE2-305 1os Honda NS50 ’90
pin up  lo bore M#  skirt  ring1 ring2  maker  price    39.5 bore, 12 pin, 19 upper
12-19-16-39.50-0 39.44 t1.2n c1.2n  generic none 13103-GE2-305 2os Honda NS50 ’90
pin up  lo bore M#  skirt  ring1 ring2  maker  price    39.75 bore, 12 pin, 19 upper
12-19-16-39.75-0 39.69 t1.2n c1.2n  generic none 13104-GE2-305 3os Honda NS50 ’90
pin up  lo bore M#  skirt  ring1 ring2  maker  price    40.0 bore, 12 pin, 19 upper
12-19-15-39.98-D 39.93 c1.5i  c1.5i   Mahle  none 2150383d Kreidler Flory D R021 40154+
12-19-15-39.99-E 39.96 c1.5i  c1.5i   Mahle   none 2150383f  Kreidler Flory F R021 40154+
12-19-15-40.00-H 39.97 c1.5i  c1.5i   Mahle   $35 2150383h (worn used)   H R021 40154+
12-19-15-40.01-K
 39.98 c1.5i  c1.5i   Mahle   $65 2152387k Kreidler Flory K R041 40154+
12-19-15-40.02-M 39.99 c1.5i  c1.5i   Mahle   $65 2152387m Kreidler Flor M R041 40154+

Kreidler 2150383 and 2152387 pistons are the same except for piston pin oil holes.

pin up  lo bore M#    skirt  ring1 ring2  maker  price    40.4 bore, 12 pin, 19.5 upper
12-19-17-40.40-0  40.32  c1.5i  c1.5i Asso     n.a. 23.0130 Morini MO1, MO2 all-iron cyl Asso 2139
12-19-17-40.40-1  40.3x  c1.5i  c1.5i Asso     n.a. 23.0136 Morini M1 (reed) with all-iron cylinder
pin up  lo bore M#    skirt  ring1 ring2  maker  price    40.6 bore, 12 pin, 19.5 upper
12-19-17-40.60-0  40.5x  c1.5i  c1.5i Asso     n.a. 23.0131/6 1os Morini MO1, MO2 all-iron cyl Asso 2139
12-19-17-40.60-1  40.5x  c1.5i  c1.5i Asso     n.a. 23.0137/6 1os Morini M1 with all-iron cylinder
pin up  lo bore M#    skirt  ring1 ring2  maker  price    40.8 bore, 12 pin, 19.5 upper
12-19-17-40.80-0  40.7x  c1.5i  c1.5i Asso     n.a. 23.0131/8 2os Morini MO1, MO2 all-iron cyl Asso 2139
12-19-17-40.80-1  40.7x  c1.5i  c1.5i Asso     n.a. 23.0137/8 2os Morini M1 with all-iron cylinder

 


20mm upper, 12 pin, Vespa L-ring

38.2 Vespa

12-20  pistons for  Vespa (Piaggio), 1995-05 Kinetic TFR

Abbreviations: C is Ciao, B is Bravo, G is Grande, S is Si 

pin up  lo bore M#  skirt  ring1 ring2  maker  price    38.2 bore, 12 pin, 20 upper
12-20-16-38.20-0 38.12 c2.0n c2.0n Piaggio $60 182591 Vespa US ’78-80 C B G says USA
12-20-16-38.20-1 38.1x L2.0n c1.5n Piaggio n.a. 191034 Vespa US ’79-86 Si, ’80-86 C B G
12-20-16-38.20-2 38.12 L2.0n c1.5n Asso    $60 3517 replacement for above

20mm upper, 12mm pin, Vespa

38.4 Vespa

pin up  lo bore M#  skirt  ring1 ring2  maker  price    38.4 bore, 12 pin, 20 upper
12-20-16-38.40-K 38.30 t1.5n  t1.5n generic n.a. Kinetic ’95-05 (Vespa remake) no arrow
12-20-16-38.40-0 38.3x c2.0n c2.0n Piaggio n.a. 112979 = 132521 Vespa ’67-76 Ciao, Boxer
12-20-16-38.40-1 38.32 c2.0n c2.0n Piaggio $50 132521 Vespa US ’76-78 Ciao, ’77-78 Bravo
12-20-16-38.40-2 38.32 L2.0n c1.5n Piaggio $65 182592 1os Vespa US ’78-86 C B G S says 1M
pin up  lo bore M#  skirt  ring1 ring2  maker  price    38.6 bore, 12 pin, 20 upper
12-20-16-38.60-0 38.54 c2.0n c2.0n Piaggio n.a. 152381 = 137681 1os Vespa ’67-76 C, Boxer
12-20-16-38.60-1 38.54 L2.0n c2.0n Piaggio n.a. 137681 1os Vespa US ’76-78 C B      says 1M
12-20-16-38.60-2 38.5x L2.0n c1.5n Piaggio n.a. 182593 2os Vespa US ’78-86 C B G S says 2M

USA piston
& cylinder

pin up  lo bore M#  skirt  ring1 ring2  maker  price    38.8 bore, 12 pin, 20 upper
12-20-16-38.60-0 38.74 c2.0n c2.0n Piaggio $60 152382 = 137682 2os Vespa ’67-76 C, Boxer
12-20-16-38.60-1 38.74 L2.0n c1.5n Piaggio $60 137682 2os Vespa US ’76-78 C B     says 2M
pin up  lo bore M#  skirt  ring1 ring2  maker  price    39.6 bore, 12 pin, 20 upper
12-20-16-38.60-0 39.47 L2.0n c1.5n Asso    $48  3517  oversize for Vespa  made in Italy
pin up  lo bore M#  skirt  ring1 ring2  maker  price    40.0 bore, 12 pin, 20 upper
12-20-17-40.00-0 39.9x t1.2n  t1.2n generic $60 633992  China 49cc two-strokes

Ch-ch-changes: Vespa standard pistons changed in 1978 and 1980. Bikes made during those years can have either the older or the newer piston. There is no way to tell by ID numbers.

20mm upper, 12 pin, China two stroke

China

1978 bore reduction: In 1978 on US models the bore was reduced from 38.4 to 38.2mm. Some ’78’s have a 38.4 bore, and some have a 38.2 bore. Same thing happened to Minarelli at that same time (a reduction from 38.8 to 38.7). The pistons changed because of legal requirements.

1979-80 Dykes upper ring: In 1979 and 1980 the upper piston ring changed to L shape known as Dykes. Some ’79’s have regular top rings, and some have Dykes. Oversize Piaggio pistons already had Dykes upper rings since about 1977. This ring style was also adopted by Derbi in the mid-70’s and Puch in the late 70’s. It was mainstream in 1979! But by the mid-1980’s L-rings became out of style and obsolete. They did cost more to make, and broke easier. There was not much benefit. So all 90’s and later two-stroke moped engines have rectangular or trapezoidal top rings, mostly thinner than older designs.  

SC means exhaust (scoria): All original pistons are made by Piaggio and say Piaggio or have the logo on the inner side. They all have an arrow on top with the letters “SC”. That means “scoria”, Italian for “exhaust”. During installation, the arrow points toward the exhaust. Vespa pistons have skirt cut-outs rotated 30 deg.

Ring gap: Piaggio specifies the ring gap to be 0.1 to 0.25 mm (0.004 to 0.010″)

10 or 12mm piston pins: Almost all of the Vespa mopeds in the USA had pistons with 12mm wrist pins, while Europe and other parts of the world have both 10 and 12mm piston pins. That is because the pin was 12mm from 1967 to 1984. And then 10mm from 1984 on. By 1984 there were not many USA moped sales. Then Vespa quit selling US mopeds in about 1985, but continued in Europe.

Piston versions: By having all of the Piaggio Parts Manuals, and especially the Parts Amendments 1, 2, 3 etc, it was possible to extract all of the Vespa (Piaggio) moped piston and ring part numbers. The millimeter sizes are not in any parts manual. They are from service manuals and actual parts new and used.

 


12-21 pistons for Minarelli V1L V1HL V1HLE, Suzuki FA50 FS50 FZ50

0000000000  part#   lower  x = 2, 3, or 4
pin up  lo bore M#  skirt  ring1 ring2  maker  price    40.3 bore, 12 pin, 21.5 upper

12-21-15-40.30-0 40.2x L2.0n c1.5n Mina.   n.a. 4541  Minarelli V1L case reed, all-iron cyl
12-21-15-40.30-1 40.2x c1.5n c1.5n Mina.   n.a. 4543  Minarelli V1HL same, sleeved al. cyl
pin up  lo bore M#  skirt  ring1 ring2  maker  price    40.6 bore, 12 pin, 21.5 upper
12-21-15-40.60-0 40.5x L2.0n c1.5n Mina.   n.a. 4551  1os Minarelli V1L
12-21-15-40.60-1 40.5x c1.5n c1.5n Mina.   n.a. 4553  1os Minarelli V1HL, V1HLE
pin up  lo bore M#  skirt  ring1 ring2  maker  price    40.8 bore, 12 pin, 21.5 upper
12-21-15-40.80-0 40.7x L2.0n c1.5n Mina.   n.a. 4561  2os Minarelli V1L
12-21-15-40.80-1 40.7x c1.5n c1.5n Mina.   n.a. 4563  2os Minarelli V1HL, V1HLE

21mm upper, 12 pin, Suzuki FA50

Suzuki FA50

pin up  lo bore M#  skirt  ring1 ring2  maker  price    41.0 bore, 12 pin, 21 upper
12-21-15-41.00-0 40.92 t1.5n  t1.5n Suzuki n.a. 12110.43000Suzuki FA50, FS50, FZ50
pin up  lo bore M#  skirt  ring1 ring2  maker  price    41.5 bore, 12 pin, 21 upper
12-21-15-41.50-0 41.4x t1.5n  t1.5n Suzuki n.a. 12100.35611.050 1os Suzuki FA50, FS50, FZ50
pin up  lo bore M#  skirt  ring1 ring2  maker  price    42.0 bore, 12 pin, 21 upper
12-21-15-42.00-0 41.9x t1.5n  t1.5n Suzuki n.a. 12100.35611.100 2os Suzuki FA50, FS50, FZ50

 


22mm upper, 12 pin, Sachs 504/505

Sachs 504 1A

12-22  pistons for Minarelli V1, V1H, Sachs 504, 505, Morini S5

pin up  lo bore M#  skirt  ring1 ring2  maker  price    38.0 bore, 12 pin, 22 upper
12-22-14-38.00-0 37.95 c1.5n c2.0n Mahle  n.a. 0286-378-051  Sachs 504,505 1C,1D  553
12-22-14-38.00-1 37.95 c1.5n c2.0n generic $55 406500 Sachs 504,505 1C,1D  says 38
12-22-15-38.00-0 37.93 c2.5n c2.5n Asso    $75 71.0455.0=4500 early Minarelli says Asso 825
12-22-15-38.00-0 37.93 c2.5n c2.5n Asso    $00 ’56-70+ Min. P3, others ’69-79 Min. V1 1hp
12-22-15-38.00-0 37.93 c2.5n c2.5n Asso    $00 ’51-55  FBM P48, P3, ’56-66 Morini F1, 3M
12-22-16-38.00-A 37.95 c2.0n c2.0n AMF     $60
original AMF BHE900 rear eng, says 38
12-22-16-38.00-0 37.95 c2.0n c2.0n Meteor $60 Sachs replacement sort B says Z21  38

12-22-17-38.00-0 37.96 c2.0n c2.0n Mahle   n.a. 0286-378-005 Sachs  552 says 37.98 G8
12-22-17-38.00-1 37.93 c2.0n c2.0n Asso    $59 23-0101 Morini S5K, S5K2 says Asso 771
12-22-17-38.00-2 37.96 c2.0n c2.0n Meteor $60 PC0922D Sachs 504,505 1A,1B  Italian made

Morini S5K2

pin up  lo bore M#  skirt  ring1 ring2  maker  price    38.2 bore, 12 pin, 22 upper
12-22-16-38.20-0 38.1x c2.5n c2.5n Asso    n.a. 71.0455.7=4510 1os Minarelli V1 1hp 20mph
12-22-17-38.20-1 38.1x c2.0n c2.0n Asso    n.a. 23-0102 1os Morini S5K2, can use Min. 4510?
pin up  lo bore M#  skirt  ring1 ring2  maker  price    38.4 bore, 12 pin, 22 upper
12-22-16-38.40-0 38.3x c2.5n c2.5n Asso    n.a. 71.0455.7=4520 2os Minarelli V1 1hp 20mph
pin up  lo bore M#  skirt  ring1 ring2  maker  price    38.6 bore, 12 pin, 22 upper
12-22-14-38.60-0 38.55 c1.5n c2.0n Mahle  n.a. 0286-378-052 1os Sachs 504,505 1C,1D

12-22-16-38.60-0 38.5x c2.5n c2.5n Asso    n.a. 71.0455.7=4530 3os Minarelli V1 1hp 20mph

22mm upper, 12 pin, Minarelli V1

Minarelli

12-22-17-38.60-1 38.55 c2.0n c2.0n Mahle  $60 0286-378-006 1os Sachs 504,505 1A,1B
pin up  lo bore M#  skirt  ring1 ring2  maker  price    38.7 bore, 12 pin, 22 upper
12-22-16-38.70-0 38.62 c1.5n c1.5n Mina.   n.a. 71.0406.0=4535 Minarelli V1 ’78-on-USA
pin up  lo bore M#  skirt  ring1 ring2  maker  price    38.8 bore, 12 pin, 22 upper
12-22-16-38.80-0 38.72 c1.5n c1.5n Mina.   $75 71.0410.0=4540 Min.V1 pre-’79-US
12-22-16-38.80-0 38.72 c1.5n c1.5n Minn.   $00 Minarelli P4 iron cyl
12-22-16-38.80-1 38.72 c1.5n c1.5n GOL     $60 0034 Minarelli V1 exact replacement
12-22-16-38.80-2 38.73 L2.0n c2.0n Asso    $60 4540HP  Demm Smily piston, fits Minarelli

Mor. S5R S5E

pin up  lo bore M#  skirt  ring1 ring2  maker  price    39.0 bore, 12 pin, 22 upper
12-22-16-39.00-0 38.92 c1.5n c1.5n Mina.   $73 71.0460.7=4550 1os Minarelli V1
12-22-15-38.96-0 38.94 L2.0n c2.0i Asso    $70 23-0133A Morini S5R, S5E Asso 1386
12-22-15-38.99-0 38.95 L2.0n c2.0i Asso    n.a. 23-0133B Morini S5R, S5E Asso 1386
12-22-15-38.99-0 38.96 L2.0n c2.0i Asso    n.a. 23-0133C Morini S5R, S5E Asso 1386
12-22-15-38.99-0 38.97 L2.0n c2.0i Asso    n.a. 23-0133D Morini S5R, S5E Asso 1386
12-22-15-38.99-0 38.98 L2.0n c2.0i Asso    n.a. 23-0133E Morini S5R, S5E Asso 1386
pin up  lo bore M#  skirt  ring1 ring2  maker  price    39.2 bore, 12 pin, 22 upper
12-22-16-39.20-0 39.12 c1.5n c1.5n Mina.   n.a. 71.0460.7=4560 2os Minarelli V1
pin up  lo bore M#  skirt  ring1 ring2  maker  price    39.4 bore, 12 pin, 22 upper
12-22-16-39.40-0 39.32 c1.5n c1.5n Mina.   $75 71.0460.7=4570 3os Minarelli V1

12-22-16-39.40-0 39.3x c1.5n c1.5n Minn.   n.a. original  Harley Davidson M50 std

Connection:
1950’s to 1970’s

pin up  lo bore M#  skirt  ring1 ring2  maker  price    39.6 bore, 12 pin, 22 upper
12-22-16-39.60-0 39.52 c1.5n c1.5n Mina.   n.a. 71.0460.7=4580 4os Minarelli V1
pin up  lo bore M#  skirt  ring1 ring2  maker  price    39.8 bore, 12 pin, 22 upper
12-22-16-39.80-0 39.7x c1.5n c1.5n Mina.   n.a. 71.0460.7=4590 5os Minarelli V1
pin up  lo bore M#  skirt  ring1 ring2  maker  price    40.0 bore, 12 pin, 22 upper

12-22-16-40.00-0 39.9x c1.5n c1.5n Asso?   n.a. 208703.2.150 Garelli Monza GT,
12-22-16-40.00-0 39.9x c1.5n c1.5n Asso?   none has port window(s), flat top
pin up  lo bore M#  skirt  ring1 ring2  maker  price    45.4 bore, 12 pin, 22 upper

12-22-18-45.40-0 45.33 c1.5n c1.5n Mina.   $70 71.0485.7 Minarelli 70cc new in box
pin up  lo bore M#  skirt  ring1 ring2  maker  price    46.0 bore, 12 pin, 21.5 upper
12-22-15-46.00-0 45.93 L2.0n c1.5i  Asso    $70 23-0140 Morini 70cc, says Asso W 2508 
pin up  lo bore M#  skirt  ring1 ring2  maker  price    47.1 bore, 12 pin, 22.5 upper

12-22-15-47.10-0 47.03 L2.0n c1.5i  Asso    $70 23-01?? Morini 70cc AW 2666, AA on top

Garelli Monza piston

 


Casal 40mm piston top

Ø40 top

Casal 40mm piston bottom

says 401

12-23 pistons for Casal M140 engine on K177, Zundapp?

pin up  lo bore M#  skirt  ring1 ring2  maker  price    40.0 bore, 12 pin, 23 upper
12-23-16-39.98-D 39.96 c2.0n c2.0n Mahle  $70 Casal alum cyl 39.98 D  Mahle 401
12-23-16-39.99-E 39.97 c2.0n c2.0n Mahle  n.a. Casal alum cyl 39.99 E  Mahle 401
12-23-16-40.00-F 39.98 c2.0n c2.0n Mahle  n.a. Casal alum cyl 40.00 F  Mahle 401

Casal Ø48 Piston top

Ø48 top

Casal Ø48 piston bottom

says 481

pin up  lo bore M#  skirt  ring1 ring2  maker  price    48.0 bore, 12 pin, 23 upper
12-23-16-47.98-D 47.96 c2.0n c2.0n Mahle  n.a. Casal alum cyl 47.98 D  Mahle 481

12-23-16-47.99-E 47.97 c2.0n c2.0n Mahle  n.a. Casal alum cyl 47.99 E  Mahle 481
12-23-16-48.00-F 47.98 c2.0n c2.0n Mahle  n.a. Casal alum cyl 48.00 F  Mahle 481

Casal (made in Portugal) pistons are made in Germany by Mahle. They say “saida” on top, exhaust side, Portuguese for “outlet”.

Casal pistons have an unusual flat bottom. They have a total height of 50mm. Top edge to pin is 23mm, plus pin 12mm, plus pin to bottom edge 15mm. There are two bore choices 40 and 48mm, each with several 0.01mm (micro!) increments to get a precise fit. A cylinder of letter “F” should get a matching “F” piston, unless it is worn, then maybe a “G” or even an “H” would be best. If the piston fit is too loose the engine will be weak, noisy, and fussy. Too tight and it will seize and do damage. Piston rings are both size 40 x c2.0n (FG gap style), like Garelli. 

 


Indian 4-stroke

13-14 pistons forIndian 78-81 AMI-50, Honda 75-77 PC50K1

pin up  lo bore M#  skirt  xxxxooo  price    42.0 bore, 13 pin, 13.5 upper
13-14-14-42.00-0 41.96 bare xxx  $48 E650-00-50 Indian AMI50, Honda PC50K1
13-14-14-42.00-1 41.96
complete $78 6131 standard size
pin up  lo bore M#  skirt  xxxxooo  price    42.25 bore, 13 pin, 13.5 upper
13-14-14-42.25-0 42.21 bare xxx  $48 E650-10-50 1os In. AMI50, Hon PC50K1
13-14-14-42.25-1 42.21 complete $78 6132 1os first over size

 


13-15 pistons for Motobecane 1977-80 40, 50, 50V Mobylette

pin up  lo M#  skirt  ring1 ring2  maker  price    39.0 bore, 13 pin, 15.5 upper
13-15-22-W  38.92  c2.0i   c2.0i  MBK   $70 22273 alu cyl 38.92 sort W
13-15-22-AA 38.93  c2.0i   c2.0i  MBK   $70 22274 alu cyl 38.93 sort AA
13-15-22-A   38.94  c2.0i   c2.0i  MBK   $70 22275 alu cyl 38.94 sort A
13-15-22-C   38.95  c2.0i   c2.0i  MBK   n.a. 22276 alu cyl 38.95 sort C
13-15-22-E   38.96  c2.0i   c2.0i  MBK   $75 22277 alu cyl 38.96 sort E
13-15-22-G  38.97  c2.0i   c2.0i  MBK   n.a. 22278 alu cyl 38.97 sort G
13-15-22-J   38.98  c2.0i   c2.0i  MBK   n.a. 22279 alu cyl 38.98 sort J
13-15-22-L   38.99  c2.0i   c2.0i  MBK   n.a. 22280 alu cyl 38.99 sort L
13-15-22-N  39.00  c2.0i   c2.0i  MBK   $75 22281 alu cyl 39.00 sort N
13-15-22-P   39.01  c2.0i   c2.0i  Θ BK  $75 22435 alu cyl 39.01 sort P  says P
pin up  lo M#  skirt  ring1 ring2  maker  price    39.12 bore, 13 pin, 15.5 upper
13-15-22-O  39.11  c2.0i   c2.0i  Θ BK  $75 22435a al cyl 39.12 oversize

piston-cylinder clearance 0.005-0.010 mm (0.0002-0.0004″), maximum 0.05 mm (0.002″)
ring gap 0.10 – 0.20 mm (0.004-0.008″), maximum 0.40 mm (0.016″)


Jawa USA

14-18 pistons for Jawa Babetta 207 1970-83

Jawa original pistons were sold with rings, but without pin or clips.

pin up  lo bore M#  skirt  ring1 ring2  maker  price    39.0 bore, 14 pin, 18 upper
14-18-15-39.00-0
38.94 L2.0n none Meteor n.a. 281218a xxxx  Jawa 210?  

Jawa 207

pin up  lo bore M#  skirt  ring1 ring2  maker  price    39.03 bore, 14 pin, 18 upper
14-18-15-39.02-0 38.97 c2.0i   c2.0i Jawa    n.a. 281218A xxxx  Jawa 207, says A Y
14-18-15-39.03-0 38.98 c2.0i   c2.0i Jawa    n.a. 281218B xxxx  Jawa 207, says B Y
14-18-15-39.04-0 38.99 c2.0i   c2.0i Jawa    n.a. 281218C xxxx  Jawa 207, says C Y
pin up  lo bore M#  skirt  ring1 ring2  maker  price    39.28 bore, 14 pin, 18 upper
14-18-15-39.27-0 39.22 c2.0i   c2.0i Jawa    n.a. 281218/1A 1os Jawa 207, says 1A Y
14-18-15-39.28-0 39.23 c2.0i   c2.0i Jawa    $60 281218/1B 1os Jawa 207, says 1B Y
14-18-15-39.29-0 39.24 c2.0i   c2.0i Jawa    n.a. 281218/1C 1os Jawa 207, says 1C Y
pin up  lo bore M#  skirt  ring1 ring2  maker  price    39.53 bore, 14 pin, 18 upper
14-18-15-39.52-0 39.47 c2.0i   c2.0i Jawa    n.a. 281218/2A 2os Jawa 207, says 2A Y
14-18-15-39.53-0 39.48 c2.0i   c2.0i Jawa    n.a. 281218/2B 2os Jawa 207, says 2B Y
14-18-15-39.54-0 39.49 c2.0i   c2.0i Jawa    n.a. 281218/2C 2os Jawa 207, says 2C Y

pin up  lo bore M#  skirt  ring1 ring2  maker  price    39.78 bore, 14 pin, 18 upper
14-18-15-39.77-0 39.72 c2.0i   c2.0i Jawa    n.a. 281218/3A 3os Jawa 207, says 3A Y
14-18-15-39.78-0 39.73 c2.0i   c2.0i Jawa    n.a. 281218/3B 3os Jawa 207, says 3B Y
14-18-15-39.79-0 39.74 c2.0i   c2.0i Jawa    n.a. 281218/3C 3os Jawa 207, says 3C Y

pin up  lo bore M#  skirt  ring1 ring2  maker  price    40.03 bore, 14 pin, 18 upper
14-18-15-40.02-0 39.97 c2.0i   c2.0i Jawa    n.a. 281218/4A 4os Jawa 207, says 4A X
14-18-15-40.03-0 39.98 c2.0i   c2.0i Jawa    $65 281218/4B 4os Jawa 207, says 4B X
14-18-15-40.04-0 39.99 c2.0i   c2.0i Jawa    n.a. 281218/4C 4os Jawa 207, says 4C X

Jawa Pistons

 

 Size translation: The table says a “1B” piston is 39.21 mm, measured “34,5mm from the base” just below the lower ring. Four “1B” pistons actually measured 39.21 there, and 39.23 at the skirt. Other “1B” pistons were 39.20 and 39.22, 39.21 and 39.22, and 0.02 more at the skirt. Other samples were “B” (standard) 38.94 and 38.96, “2B” 39.44 and 39.46, “3B” 39.70 and 39.73, “4B” two at 39.95 and 39.97, all 0.02 wider at the skirt. Based on these eleven new pistons, all measured the same way at the same time, the Jawa piston sizes can be translated to standard piston sizes. Jawa piston sizes (measured at the lower ring) are, on average, 0.02 mm less than standard piston sizes (measured at the skirt).

Piston to cylinder clearance: From the Puch service manual the piston to cylinder clearance for a similar steel sleeved aluminum cylinder, is min 0.030, max 0.055 mm. From the Jawa table of piston sizes (at right), it says the new piston-to-cylinder clearance is min 0.065, max 0.075 mm. Subtracting 0.02 mm from this gives min 0.045, max 0.055, more in agreement with Puch. 

 


Flandria

14-24 pistons for Flandria Bermuda

pin up  lo bore M#  skirt  ring1 ring2  maker  price    40.0 bore, 14 pin, 24 upper
14-24-12-40.00-0 39.9x c1.5n c1.5n Fland. n.a.  Flandria Bermuda 1977

This is unusual in many ways. The transfer flows through the piston instead of around it.
The wrist pin is lowered to allow more intake air flow. This upper length of 24 is the most for 50cc pistons. The wrist pin measures 13.98 x 33 mm.

 

 

 

 

100’s more vintage replacement pistons of all sizes are in the GOL Pistons Vintage Catalog, a pdf download.