Gurtner Carburetors

July 14, 2016

Gurtner

Contents (carburetor families):
1.  AD  on ’81-83 Motobecane  
 

2. D, E on ’75-83 Peugeot 102, 103
3. AR2 on ’70-80 Motobecane 40, 50
4. AR1 on ’66-78 Motobecane 7, Cady
5.  BA  on ’60-69 Motobecane, Raleigh
6.  AR  on ’55-65 Motobecane, Riverside

7. Floats
8. Jets
9. More  

 

Jules Gurtner started making carburetors in 1907, for some of the earliest automobiles and motorcycles.

Gurtner carburetors are made in France, and original on French mopeds Peugeot and Motobecane. See also mopedarmy.com

Gurtner early M18D M20D M22D M23.5D M25D

1940’s M series

Gurtner early M series article from 1945

1945 M series

 

 

 

 

 

 

 

 

Gurtner Master Catalogs: Here are the 1961 Gurtner Catalog and the 1980 Gurtner Catalog from motobec.fr. 

Gurtner Moped Carburetors: Here are the 1961 Carb List and the 1980 Carb List. From those you can see that about one third of all Gurtner carbs are for mopeds (mobylettes). Before 1960, most Mobylettes had 10mm carburetors (or 8.7). So the speed and power were limited to be under about 25mph. After 1959, some had 10mm carbs and went 25mph, and some had 13mm carbs and went 30-35mph.

Much of this information and photos are from the Motobecane Club of France.

 

 


M

1. Gurtner AD

 

AD was the last Gurtner carburetor on Motobecane/MBK mopeds, before the change to Dellorto SHA.

AD Carb List

AR2float 0 slide 0000 jet  000 diffuser       air box
float 000 slide 00000  jet  000 diffuser   assm.   bare

∅13 AD13-858-A  7/82  parts list
1980’s Motobecane 99Z, 94Z
13105  13138 ∅15? 9831/78   13345 0  13104  13185

∅13 AD13-915   parts list
1980’s Motobecane/MBK 51V
13105  13416 ∅15? 9831/78   11316 0  13534  11301

∅13 AD13-945   parts list
1980’s Motobecane/MBK 51S
13105  13416 ∅15? 9831/76   14097 0  13534  11301

 

 


2. Gurtner D and EPeugeot 1980 tiny

D8.5G, D10G, D12G, E12B carburetors
1975-83 Peugeot 102, 103 (US models)

 

Gurtner Peugeot remake

generic D12G remake

Gurtner D12G-724F

 

 

 

 

 

 

 

 

1980 102 SP U3 D12.698.G.1.80

Gurtner D12G-698

 

 

1980 Peugeot 102 SP U3 with
Gurtner D12G-698 carburetor
says D12.698.G.1.80 (Jan 80)

 

 

 

 

102 has a fixed engine and piston port intake, to cylinder.
103 engine swings and has a reed valve intake, to case.
USA versions: U1 (20 mph), U2 (25 mph), U3 (30 mph)

Left, 102 has a fixed engine and piston port intake, to cylinder. R, 103 engine swings on the swing arm pivot, case reed intake.

 

D, E Carbs

AR2float 0 slide 0000 jet  000 diffuser       air box
float 000 slide 00000  jet  000 diffuser   assm.   bare

∅12 D8.5G-826 
1976-80 Peugeot 103 U1 (20)
6437  4649/10 ∅00 5012/240=60 fixed  9860  9860

∅10 D10G-754B  parts list
1970’s Peugeot 103? mofa (25kph)
6437  4649/10 ∅00 5012/250=63 fixed  9860  9860

∅10 D10G-918B  parts list
1970’s Peugeot 103 CH (30kph)
6437  4649/10 ∅00 5012/230=58 fixed  9860  9860

∅10 D10G-975 
1980 Peugeot 102 SP U2 (25)
6437  4649/8 ∅13   5012/220=56 fixed  9388  9388

∅12 D12G-698  1/80
1980 Peugeot 102 SP U3 (30)
6437  4649/8 ∅13   5012/245=62 fixed  9388  9388

∅12 D12G-724E  parts list
1970’s Peugeot 104 L, LV
6437  4649/8 ∅13   5012/245=62 fixed  9860  9860

∅12 D12G-724C
1976-80 Peugeot 103 U2, U3 (25, 30) 
6437  4649/8 ∅13   5012/245=62 fixed  9860  9860

∅12 E12B-738
1981-83 Peugeot 103

 

 

 

Part numbers: Peugeot is olive, Motobecane is dark orange.
102 and 103 combined. Part numbers with “b” are 102-only.
New items prices are green. Used prices are dark green.

no. price   Peug#  Gurt#  MB#  description   remarks

1    $78.0 48929 carburetor Ø12 D12G -724F
1    $00.0 48929 modern genuine with air box
1    $00.0 48929 jet 64, replaces D12G-724C
1    none  48929 carburetor Ø12 D12G -724C
1    none  48929 jet 245=59, for 103 U2, U3
1    none  58036 carburetor Ø8.5 D8.5G-826
1    none  58036 jet 240=58, for 103 U1
1b   none  46479 carburetor Ø12 D12G -698
1b   none  46479 jet 245=59, for 102 U3
1b   none  64203 carburetor Ø10 D10G -975
1b   none  64203 jet 220=54, for 102 U2
2    $45.0 48929 carb 48929 bare   good used, tested
3    $15.0 69299 4649/8 15319 throttle slide Ø13 
3    none  69445 4649/10 throttle slide Ø?? for D8.5G-826
4    $5.00 53386 17732 14107 spring Ø9.5 x 30
5    10-$7 12156 carb top bare
5    $12.0 12156 7701 top assy 5,6,8,9,10,12,13  no slide
6    $1.00 07016 10218 14311 screw M4 x 12 
7    $4.00 09939 9939 air filter bracket
7b  $0.208560993660 01088 lock washer   
8    $5.00 01510 1510 00189 adjuster M6-0.75 
9    $2.50 001511 1511 04172 adjuster nut      
10  $3.00 08947 8947 drawing rod washer 
11  $8-$5 09394 9394 drawing rod gasket 
12  18-12 09393 9393 drawing rod 
1
$8.00 09391 9391 throttle pull clip  a wire “crankshaft”
14  $2.00 06546 6546 18892 idle screw M5-0.8
15  $2.00 05072 5072 00204 idle screw spring
15  none  06546 13667 idle screw and spring
16  none  69463 5012/66 jet 260=66 0.64  (0.025″)
16  none  69462 5012/64 jet 64=255  
16  none  69461 5012/63 jet 250=63 0.63 mm
16  $19.0 69460 5012/62 jet 245=62 0.62 mm
16  $11.0 69459 5012/60 jet 240=60 0.60 mm
16  $14.0 69458 5012/59 jet 235=59 0.59 mm
16  $14.0 69457 5012/58 jet 230=58 0.58 mm
16  none  69456 5012/56 jet 220=56 0.56 mm
17  $2.00 69300 fiber washer 19 x 12.5 x 0.4   optional
18  55-35 69755 float cover w/seat     
19  $8.00 09348 9348 rubber ring 22 x 27 x 1  
20  $5.00 69754 12372 plug M12-1.0 taper seal, no gasket
21  $2.00 08048 8048 float cover strap  for 103
21b $12.009365 9365 float cover strap  for 102
22  $0.60 10306 10306 13392 screw M5 x 10       
23  45-30 06437 6437 float w/needle          
23  $15.0 06437 6437 float w/needle modern replacement
24  $8.00 04159 4159 14133 fuel filter screen
25  none  09860 9860 air box with filter   for 103
26  $12.0 09672 9672 air filter gasket          
26b$39.0 09388 9388 air box with filter   for 102
27  $18.0 09286 9286 air filter step-screw for 103
27b none 09395 air filter step-screw   for 102 (use 103 type)
28  $1.00 68239 9617 19689 screw M3-0.5 x 6
29  $6.00 68239 clamp bolt M6 special  
30  $0.4083208700010 clamp bolt nut
31  $10.0 68202 23134 mount clamp w/bolt  

 

1970's 103 types had Gurtner D12 carburetors. '81-on 103/104 had Gurtner E12B carburetors.

1970’s 103 types had Gurtner D12 carburetors.
’81-on 103/104 had Gurtner E12B carburetors.

 

 

 

 

 


3. Gurtner AR2 M

 

Gurtner AR2 series moped carburetors have a large flange, like a wall. It is for an “air box”, a noise silencing, fuel mist recovering, and air filtering chamber. There are two (venturi) sizes, 10 or 12 mm, and two styles, side or center mount. Center and side mount carbs look the same, but don’t interchange completely.

Gurtner AR212/R705 remake

AR2-12-705 remake

Gurtner AR210-R991

Gurtner AR2-10-991

 

 

 

 

 

 

 

 

Motobecane 30mph variator side-mount carb with long pipe

side mounted AR2 carburetors

 

Motobecane 20mph no-variator side-mount carb with thin long pipe

side mount thin pipe

40TS side mount with top-pull choke

 

 

 

 

 

 

 

Side mount carburetors have threads for an air filter stud, side holes for a center mount air box clip, and clamp to a 19mm intake pipe. The side mount float top cover has a vertical fuel hose spigot. A stripped bare side mount body, as is, will exactly replace a bare center mount body.

 

Motobecane 30mph variator center-mount carb with short pipe

center mounted AR2 carburetors

Center mount carburetors have no threads in the stud hole, side holes for a center mount air box clip, and have removable sleeves, black 16 x 19 (for AR210), and white 17 x 19mm (for AR212). The sleeves reduce the precision clamp size from 19mm to 16 or 17. The purpose is to be tamper resistant. The sleeves fit tight and are difficult to remove without damaging them. The center mount float top cover has a horizontal fuel hose spigot. A stripped bare center mount body, after threads are cut in the air box post hole, will replace a bare side mount body.

Center mount early  Some pre-USA years 1960’s or early 1970’s had no fuel hose inlet in the float top cover. Instead it was in the carburetor body just below the float top. This type is in many Motobecane USA parts illustrations, but it was not used on any, or hardly any US models. In the illustration below it was edited out. Out of 47 original carbs, taken off once-living Motobecanes from around Southern California, none were this “center mount early” type with the fuel hose spigot in the carb body.

 

OEM Replacements Motobecane USA 1976-80  
7776
is pre-1978 12mm, 5mm stud, thin mount.

13512 is 1978-on 12mm, 6mm stud, thick mount.
13510 is 1978-on 10mm, 6mm stud, thick mount.

In 1977 the air box stud 5 mm threads would sometimes get stripped, or the clamp mounts would sometimes break. So during 1978, on some they made the air box stud 6 mm and the casting thicker at the mount. From 1979-on all were 6 mm.

MB carb mounts early (thin) and late (thick).

MB carb mounts
early (thin)
and late (thick).

 

Mount Type: All Motobecane carbs clamp to 19.0mm inlet pipes. But many of the pre-March 1978 carburetors were cracking at the edge of the clamp, or the base of the petals. So Gurtner beefed up the carb body with a reinforcing ring, made the clamp petals about 1mm thicker each, and changed the clamp to the bigger Peugeot double-wall type.

Air Filter Stud: When the mount was made stronger in 1978, the air filter post was also beefed up from 5mm to 6mm. This made the threads in the body more resistant to stripping. Another issue that was improved is when the air filter stud is over tightened, a bulge can form in the float chamber wall behind it. That bulge makes the float stick. See below.

Center Mount Air Cover: The center mount type (short and deep) air box is too deep and sticks out too much as a side mount. The right side engine cover panel must be removed, and some kind of high-offset right pedal crank arm installed. Then maybe pedal threads are different.

Side Mount Air Cover: The side mount type (tall and flat) air box is too tall and hits the frame as a center mount. More importantly, they break, fall off, and get thrown away, in addition to getting lost. Because of that, they have become scarce and pricey. From 2000-2015 maybe 200 people have asked for this item, but only two were available and sold at MM.

Gurtner Motobecane air box covers

Three views of the side (L) and center (R) types of MB air box covers

 

Motobecane side mount air box nut and cupped washer upgrade

Side mount air cover breaks without cupped washer/nut.

The Motobecane piston-port two-stroke engine needs the air cover because the gasoline mist flows in and out in both directions. So there is a little cloud of fuel and oil mist out in front of the carburetor. Without the air cover, this fuel cloud gets wasted and blown away (or ends up on the riders right leg or shoe). Besides that, the air cover provides the correct amount of flow restriction, which is a good thing, up to a point. See below about running without an air cover (how it can damage the engine by over-heating from not enough fuel and oil).

 

 

 

 

 

Air cover substitution: Here is a center-mount air cover installed on a side-mount carburetor. Holes have to be drilled for the mounting wire clip, and the lower right corner has to be warmed up and molded inward where it touches the round magneto base plate. More importantly, the side cover must be removed, and it almost touches the pedal. So it’s easy to kick it when pedalling.

 

AR2 Carbs

AR2float 0 slide 0000 jet  000 diffuser       air box
float 000 slide 00000  jet  000 diffuser   assm.   bare

∅10 AR2-10-910  parts list  side mount B
54115 (use 13510), bare 52435, stud 5
77-78 MB 50V (20mph) to 12/78
4901  4649/10 ∅13  581/52  9529/3=20573  12330

∅10 AR2-10-737 and 991  3/77-11/79 center mt. A
52175 (use 13510), bare 52430,
77-79 MB 50V (25 mph) 4/77 on
4901  4649/10 ∅13 0 K80 00 0000/0=52560  12330

∅12 AR2-12-705  7/75-01/77 center mount A
20026 (use 7776), bare 53657,
75-77 MB 50V (30) to 3/77, AV88, 68, 49, 40, 50
4901  8474/6 ∅14  581/B54  9346/1=19990  8437

∅10 AR2-12-729  11/75-1/79 side mount B
22160, bare 54466, pre-78 is stud 5 (use 7776)
22160, bare 54466, 78-on is stud 6 (use 13512)

74-79 MB 40, 50 (25 and 30 mph)
4901  8474/6 ∅14  581/B56  0000/0=21002  12330

∅12 AR2-12-873  3/77-11/79 side mount B
54973, bare 54466, pre-78 is stud 5 (use 7776)
54973, bare 54466, 78-on is stud 6 (use 13512)

77-79 MB 50V (30 mph) 4/77-3/80
4901  8474/6 ∅14  581/B56  0000/0=22937  12330

∅12 AR2-12-978  4/80  side mount B
77-79 MB 50V (30 mph) 4/80-12/80
4901  8474/6 ∅14  581/B56  0000/0=22937  12330 

∅13 AR2-13-712
19xx Motobecane SP94
4901  slide ∅14

 

Key: A = center mount carb only   B = side mount only

New prices are green. Used prices are dark green.

 

  pic  price  MB no.   description          remarks
    A $110  20026 carb AR2-12-705  no air cover
    A none  52175 carb AR2-10-991
    B $180  54973 carb Ø12  7776     no air cover
    B none  54973 carb Ø12 13512    no air cover
    B $120  22160 carb AR2-12-729  no air cover
    B none  54115 carb Ø10 13510 
  1A $65.0 53657 Ø12 carb bare   for AR2-12-705
  1A none  52430 Ø10 carb bare   AR2-10-991 & 737
  1B $50.0 54466 Ø12 carb bare   AR2-12-873 & 729
  1B none  54235 Ø10 carb bare   for AR2-10-910
  2A $39.0 18355 air filter cover   for center mount
  2B none  20949 air filter cover   for side mount
  3A $12.0 15041 air filter screen  for center mount
  3B $6.00 20999 air filter screen  for side mount
  4A $12.0 18356 spring clip         for center mount
  4B $4.00 m6cup cupped washer upgrade, see above
  5B $1.00 m5lock M5 nylock nut   for M5 stud
  5B $1.00 m6lock M6 nylock nut   for M6 stud
  5B $2-$1 13339 M5 knurled nut  for M5 stud
  6B $5.00 21000 stud 5mm         side mount pre-79
  6B $8.00 23562 stud 6mm         side mount 78-on
  6B $5.00 special M6-M5 step stud for stripped M5 hole
  7B $3.00 20997 air filter gasket  18 x 21 x 1.5mm
  8B $8.00 20996 air filter 5mm     side mount pre-79
  8B $20.0 23561 air filter 6mm     can drill a 5 to 6
  9   $1.00 19689 taper screw M4-0.7 x 6/8 on USA models
10   $1.00 19767 bolt M5-0.8 x 44    M5 w/flange 10 hex
11   $2.00 15326 fiber washer 5mm 5 x 10mm
12   $6.00 20475 o-ring 21×24 x 1.5  this is optional
12   $0.00 somehow, removing this often makes it leak less
13A $5.00 00189 adjuster M6-0.75   A13
13B $16.0 21940 cable guide, used   for side mount
14   $0.50 18893 screw M5-0.8 x 12  
15   $0.20 01271 washer M5           
16A $12.0 21229 slide cap M6-0.75   threaded for adjuster
16B $5.00 21696 slide cap                recessed for elbow
17   $5.00 14107 spring Ø9.5 x 30    same as Peugeot
18   $15.0 15319 throttle slide Ø13   for AR210 & Peugeot
18   $15.0 19278 throttle slide Ø14   for AR212 carbs
19   $7.00 14120 choke spring       
19B $2.00 22935 choke cable ring    cable end adapter
20   $9.00 14119 choke slide brass   stepped 6.3 x 5.7 x 15
20B $8.00 22936 choke push rod      original white plastic
20B $3.00 22936 substitute (adjuster A2)
21   $2.00 00204 idle spring 7.5 x 11 
22   $2.00 18892 screw M5-0.8 x 16  same as Peugeot
23   $5.00 00208 bolt assy M6-1.0 
24   $3.00 00878 tall nut M6-1.0   12mm tall 8mm hex
25   $2.00 15043 clamp for ∅21.7 (to 3/78)
26   $10.0 23134 clamp for ∅23.5 (4/78-on) 
26A none  14100 sleeve 19×16 black   for AR2-10-991
26A $21.0 16630 sleeve 19×17 white  for AR2-12-705
26B none   22689 rubber washer 15 x 19 x 2
27   $9.00 18880 float gasket   
28   $8.00 14133 fuel filter/screen     same as Peugeot
29   45-25 14101 4901 float
30B $38.0 22937 slide diffuser Ø0.91  AR2-12-873 & 978
30A $7.00 19990 slide diffuser Ø1.50  for AR2-12-705
30A none  20573 slide-fit diffuser Ø?   AR2-10-910 pre-78
30A none  54237 slide diffuser Ø1.50  AR2-10-910 ’78-on
30B $35.0 21002 slide diffuser Ø0.91  for AR2-12-729
31   $3.00 20000 collar M7-1.0           holds slide-fit diffuser
32   $1.00 19689 screw M3-0.5 x 7     M3 taper seal
33   none  52560 press diffuser Ø0.61 AR2-10-991 & 737
34A none  21228 float top horiz inlet   for center mount
34B none  22161 float top vert inlet    for side mount
35   none  22339 float top no inlet      for carb w/inlet
36   $17.0 23545 581/52 jet 0.52 mm 210cc  for AR2-10-910
36   none  21841 581/52 jet 0.52 mm   #52  
36   $10.0 23546 581/54 jet 0.54 mm 220cc  for AR2-12-705
36   $14.0 21843 581/54 jet 0.54 mm   #54  for 
36   $19.0 23547 581/56 jet 0.56 mm 230cc  AR2-12-873 & 978
36   $19.0 21949 581/56 jet 0.56 mm   #56  for AR2-12-729
36   $15.0 00000 581/57 jet 0.575mm   #00 drilled w/#74 drill
36   $19.0 23548 581/58 jet 0.58 mm 240cc  for AR1-10
36   $19.0 22938 581/58 jet 0.58 mm   #58  
36   $19.0 23549 581/60 jet 0.60 mm   #60  for AR1-10
36   $15.0 00000 581/61 jet 0.615mm   #00 drilled w/#73 drill

36   $15.0 00000 581/64 jet 0.64 mm    #00 drilled w/#72 drill
36   $19.0 51052 000/00 jet 0.80 mm   K80  AR2-10-991 & 737
40   $17.0 aftermarket AR2 Carb Kit correct only for AR2-12-705

Choke Slide: This is often mysteriously missing, but actually stuck in the lowest (normal) position, either by tar or corrosion. It can be unfroze with solvent and/or by removing the cable wire and pushing it up from the bottom by tapping with a small punch and hammer. When the choke slide is pulled up, the choke is “on” for cold starting, and an extra fuel path is exposed by the step in the choke slide. If the choke slide is actually missing, the choke would be “on” all the time, but some extra air gets in along with the extra fuel. So the net effect of running without a choke slide is minor. 

Top Pull or Bottom Pull Choke Cable:

1. On center mount carburetors, for variator models, the choke cable is “top pull”. The choke and throttle cables detach, allowing the carburetor to be serviced away from the bike.

Gurtner MB Top pull choke cable routing

Gurtner AR2 top pull choke cable routing

2. On side mount carbs for non-variator (Dimoby) models, the choke cable is “top pull”, but has a elbow (curved tube), like the throttle cable. The choke and throttle cables detach, allowing the carburetor to be serviced away from the bike.

Gurtner MB bottom pull choke parts exposed

AR2 bottom pull choke parts exposed

3. On side mount carbs for ’78-later 30mph variator models, the choke cable is “bottom pull”, where the choke wire runs through the carb body, trapping it on or near the bike. On those most service operations are done with cables attached, about one foot away from the bike. To remove the carb you have to pull the choke wire all the way out. Then it won’t usually go back because the braided end gets frayed. Then the choke wire has to be replaced. 

 

 Le Diffuseur: When you look down the “throat” or venturi of a Gurtner carburetor, with the throttle wide open (throttle slide up and out of the way of the air), the little brass tube that sticks up from the floor of the venturi is the diffuser. It sprays the gasoline mist sucked up by the moving air.

Left, top are the way more common type, the “slide fit” type diffusers. Can you see, besides the main large hole down the middle, that each diffuser has two small holes facing out of the page? Those are the idle holes. When they are blocked, the engine will run OK, but will not run slow or “idle”. On a 21002 diffuser the idle holes are 0.016″. That size hole is cleaned with a #78 drill, also 0.016″.

Left, bottom are the less common type, the “press fit” type diffusers. You can only see one idle hole on this kind, but there is another on the opposite side. These diffusers have a very small center hole, that serves has the limiting jet. They are installed by pressing in from above, instead of sliding in from below like the other kind. The purpose of this type is to be tamper resistant. There is no particular direction that they have to be aimed at, and no flat side in the carb body for that purpose.

 


Additional Information:

Motobecane 20mph carb sliced in half

Slide Fit and Press Fit Diffusers: Some Motobecane carburetors have “press fit” diffusers, instead of the usual “slide fit”. This is one of those types (AR2-10-737 or AR2-10-991 or perhaps others) that has been sliced in half to expose it’s secrets.

While “slide fit” diffusers slide in and out from the bottom, this “press fit” diffuser 52560, and carburetor type, slides (presses actually) in or out from the top. Many of these get smashed on top by Motobecane mechanics trying to push the diffuser downwards, the normal way out.

Press-fit-diffuser carburetors cannot be made to accept slide fit diffusers. 

 

Motobecane Choke Circuit cut away

Choke (cold starting) system: Unlike the Peugeot Gurtner and most other moped carburetor chokes, the Motobecane Gurtner AR2 has an additional fuel path or tunnel. It’s “choke” is a fuel enrichment device rather than an air restricting device. The choke circuit is completely independent of the main fuel circuit. It has it’s own fuel tunnel out of the float bowl, that bypasses the throttle slide, diffuser, and jet. 

Original Equipment Carbs have Dates: This carburetor clearly shows it’s manufacture date of 5/77, below the model number. It could be from a late 1977 or a 1978 bike. The 39 used Gurtner AR2 carburetors in Myrons Mopeds inventory on Dec 2014 have dates ranging from 03/74 to 04/80. The majority are from 1977 and 1979. See above “Population Study of Gurtner AR1 and AR2 Carburetors in Southern California”.   

 

 

 


M4. Gurtner AR1

 

Parts for five Gurtner AR1 carburetors are listed here, combined into one list using quantity colums a,b,c,d,e. 

 

a. Gurtner AR1-10-674 ’66-68 Motobecane Cady M1

 

b. Gurtner AR1-10-691 ’66-78 Cady M1P, PR, PRT, PRTS

MB Cady and MB 7 air boxes

 

c. Gurtner AR1-11.5-753 ’74-77 Cady M3PR, PRT, PRTS

 

d. Gurtner AR1-10-919 ’78 Motobecane 7 (US 20, 25)
e. Gurtner AR1-12-884
’78 Motobecane 7 (US 30mph)

1978-79 Motobecane 7

Gurtner AR1-12 carburetor complete 3 views

In US mopeds, AR1 carburetors were only on one model for one year. That lone French pony was the 1978 Motobecane Model 7. Only about 2 or 4% of the Motobecanes sold in the US were Model 7.

 

AR1 Carb List

AR1float 0 slide 0000 jet  000 diffuser       air box
float 000 slide 00000  jet  000 diffuser   assm.   bare

∅10 AR1-10-691  parts list
1966-78 Cady M1P, PR, PRT, PRTS
5186  8686 ∅00 00 581/B53    fixed 00  7679  4909

∅10 AR1-10-A691  parts list
1974-77 Cady M3PR, PRT, PRTS export
6758  8686 ∅00 00 581/B52    fixed 00  7682  11021

∅11.5 AR1-11.5-753  parts list
1974-77 Cady M3PR, PRT, PRTS
6758  4685/12 ∅00  581/B55   fixed 00  7681  11021

∅10 AR1-10-+919   parts list
1978 Motobecane 7 (20)
5186  8686 ∅00 00 581/B60   8669/1    7783  13289

∅10 AR1-10-919  3/78 parts list
1978 Motobecane 7 (25), 70’s M7
5186  8686 ∅00 00 581/B58   8669/2    7783  13289

∅12 AR1-12-884  11/77 parts list
1978 Motobecane 7 (30), 70’s M7
5186  4685/1 ∅14  581/B54   4687/3    7783  13289

 

Gurtner MB7

pic abcde price   MB#   Gurt#   description    remarks 

00 10000 none  00000 carburetor Ø10 AR1-10-674
00 01000 none  19600 carburetor Ø10 AR1-10-691
00 00100 none  00000 carbur.    Ø11.5 AR1-11.5-753
00 00010 none  54458 carburetor Ø10 AR1-10-919
00
 00001 none  23021 carburetor Ø12 AR1-12-884
01 00001 none  54454 7782 carb body bare Ø12
01 11010 none  54225 carb body bare Ø10
02 00111 $2.00 23194 9754 top screw M4-0.75 x 22
02 11000 $2.00 17760 top screw M4-0.75 x 20
03 00111 $0.20 01088 3650 washer M4 lock
03 11000 none  00943 washer M4 lock
04 11111 none  17759 8002 carb top
05 11111 $7.00 14120 3936 choke spring    
06 00011 $9.00 14119 3935 choke slide  
07 11111 $5.00 14107 3771 throttle spring 9.7 x 29
08 11010 none  19605 8086 throttle slide Ø12  
08 00101 $35.0 16629 4685/1 throttle slide Ø14
09 11111 $2.00 00204 5072 idle screw spring
10 11111 $2.00 18892 6546 idle screw
11 11111 $5.00 00208 bolt assy
12 11111 $2.00 15043 4330 clamp
13 00111 none   22689 7088/1 seal ring 15 x 19 x 2
14 
01000 none  19215 581/B48 jet 19 = 195cc = 48
14 01000 none  18973 581/B52 jet 20 = 210cc = 52
14 0000$10.0 23546 581/B54 jet 22 = 220cc = 54
14 00010 $19.0 23548 581/B58 jet 00 = 240cc = 58
14 00010 $19.0 23549 581/B60 jet 24 = 245cc = 60
15 00011 none  23196 7783 air filter assy
16 00011 none  23195 13288 air filter mount
17 00022 none  23139 13432 screw M5x10 allen
17 00022 $0.60 subst. screw M5x10 phillips
17 22200 none  19248 screw M4x10
18 00011 none  14123 5186 float
18 11100 none  16113 6758 float
19 11111 none  14103 3764 float gasket
20 00022 $0.20 01088 3680 lock washer M4
22 22200 $0.20 00943 subst. lock washer M4
21 00022 $1.00 14106 10218 float screw M4x12 phillips
22 00011 none  19143 3752 fuel filter
23 00011 $2.00 15326 14025 fiber washer 5×10
24 00011 $0.60 13245 8176 bolt M5x10 hex
25 00122 $16.0 21940 cable guide 
26 00011 none  23197 13289 air box
27 22222 none  19606 10271 wood-type screw 4 x 13
28 11111 none  19145 8523 air box clamp assy
29 00011 $50.0 23199 12931 float chamber cap

 

 

 

 


M5. Gurtner BA

 

 

1962 Riverside 14030

BA Carb List

BAfloat 0 slide 00000 jet  000 diffuser       air box
float 000 slide 00000  jet  000 diffuser   assm.   bare

∅10 BA10-549-D (BA-549-D)  7/60  parts list
1960 Mobylette
6685  4649/10 ∅13  5012/19    fixed 00  6747  4022

∅10 BA10-540-F (BA-540-F) 2/62 parts list  photos 1 2 3 4
1962 Riverside 14030
6685  4649/10 ∅13  5012/20    fixed 00  6747  4022

∅10 BA10-610-B (BA-610-B)  5/63  photos 1
1963 Raleigh RM6 Runabout
6685  4649/10 ∅13  5012/20?  fixed 00  6747  4022

∅10 BA10-610 (BA-610)  parts list  photos 1
1962 Motoconfort AU65, 60’s AV44, 76, 85
6685  4649/10 ∅13  5012/21, 20 fixed   6747  4022

∅10 BA10-610-C (BA-610-C)  10/63  photos 1 2 3 4
1962 Motobecane AV48
6685  4649/10 ∅13  5012/19   fixed 00  6747  4022

 

 

 


M6. Gurtner AR

 

 

1960 Riverside 14011

AR Carb List

ARfloat 0 slide 00000 jet  000 diffuser       air box
float 000 slide 00000  jet  000 diffuser   assm.   bare

∅10 AR10-429  parts image
1957-60 Riverside 14007A, 14010A, 14010B
5186  14124 ∅13 00  01122 0014126  00 000  15037

∅10 AR10-501  7/57  parts list
1957 Motobecane AV78 (variator)
5186  3100/10 ∅13  3983/21  5523 00  6747   4022

∅10 AR10-511  parts list
1950’s Motobecane, Dimoby (no variator)
5186  3763/8 ∅13 0 3983/20  5370 0    5946   5782

∅13 AR13-488-K  6/60  parts image
1960-62 Riverside 14010, 14010C, 14011, 14011A
5186  4685/14 ∅14  3983/21  4687 0 6904/2  4022

∅13 AR13-488  parts list
1961 Motobecane AV87 
5186  4685/14 ∅14  3983/21  4687 0 6904/2  4022

 

 

 

 

 


7. Gurtner Floats

 

Gurtner Floats

Gurtner 6437 and 4901

On 1970’s US mopeds there are 3 Gurtner floats:
5186 (Motobecane 14123) for AR1 carbs on Model 7

4901 (Motobecane 14101) for AR2 carbs on 40, 50
6437 (Peugeot 06437) for D-type carbs on 102, 103

Gurtner used to color code their new float containers green for Motobecane and red for Peugeot. Otherwise they are almost indistinguishable, unless together side by side. 

5186, 4901, 6437 specs

6685 specs

Float Service: On plastic types the needle is a press fit into the top and bottom holes in the bulb. The needle can simply need moving up or down. Or it could also need the tip straightened and/or sharpened/machined. Or the needle could need to be replaced, if it has become too short or too bent. Any piece of 1.5mm brass rod, cut to these lengths, and machined to a cone tip, would restore the float. In addition, a gasoline-proof sealant should be used to seal the press-fit holes, as a precaution, or if gasoline enters the bulb. 

Float List

Most data are from lesolex.com in France.
Most of these floats can be purchased there.
US models in blue.

13160 brass  for
needle ∅1.5 x 37.8, bulb ∅22.2
for chamber ∅23.4

1950’s Peugeot
superseded by 6437

13155 brass  for
needle ∅1.5 x 41.5, bulb ∅24.0
for chamber ∅25.2
1950’s Motobecane
superseded by 4901

6758 brass  for AR and AR¹ carbs
needle ∅1.5 x 41.7, bulb ∅22.7
for chamber ∅
for 66-78 Motobecane Cady
Motobecane #16113

5186 brass  for A, AR, AR1 carbs
needle ∅1.5 x 41.5, bulb ∅22.5 x 20.3
for chamber ∅23.6-23.9

’57-64 Ward (except 14030), 78 MB7
high bulb, Motobecane #14123

3739 brass  for C carbs: C10D
needle ∅1.5 x 41.7, bulb ∅22.5 x 20.3
for chamber ∅

for Peugeot Bima
low bulb, Peugeot #03739

6685A brass  for B, BA, BR carbs
needle ∅1.5 x 35.7, bulb ∅22.2 x 20.5
for chamber ∅23

60’s MB, Raleigh, ’61-63 Ward 14030
Motobecane #

6437 plastic for D carbs: D8.5 D10 D12
needle ∅1.5 x 37.8, bulb ∅22.0 x 20.1
for chamber ∅23.4

76-83 Peugeot 102, 103, 70’s BB
Peugeot #06437

4901 plastic for AR2 carbs
needle ∅1.5 x 41.5, bulb ∅24.0 x 20.3
for chamber ∅25.2

74-80 Motobecane 40, 50, others
wide bulb, Motobecane #14101

4901/2 plastic for E carbs: E12
needle ∅1.5 x 41.5, bulb ∅24.0 x 20.3
for chamber ∅

81-83 Peugeot 103, 80’s 104, GT10
wide bulb, Peugeot #

13105 plastic for AD carbs: AD13
needle ∅1.5 x 41.5, bulb ∅25.2 x 20.6
for chamber ∅

1980’s MBK 51, M16, 99Z 92GT
wider bulb, MBK #23135

 

 

 

 


8. Jets

There are three types of Gurtner jets (gicleurs), 581, 5012, and 9831. 

5012

M6-0.75 thread

 

 

581

M7-1.0 thread

 

 

9831

M7-1.0 thread

 

 

 

There are three size label types, here called 60’s, 70’s and 80’s.
A  581  jet, 60’s size 21, equals 70’s size 215, equals 80’s size 53.
A 5012 jet, 60’s size 21, equals 70’s size 215, equals 80’s size 54.
A 9831 jet, 60’s size 00, equals 70’s size 215, equals 80’s size 55.

Use this table to cross reference Gurtner sizes.

 

 


9. More

 

 

Population Study of Gurtner AR1 and AR2 Carburetors in Southern California

These 47 Motobecane carburetors all came from whole bikes that were stripped out for parts. The Motobecane population in the greater Los Angeles area is roughly represented by this large subset. Out of 47 carbs there were only two AR1 types, from Model 7. All of the 45 others were from Models 40 and 50. 

Year  Qty  Carb Type   Mount   Dates


1974   1  AR2-12-774   center  03/74


1975   7  AR2-12-705   center  07/75 07/75 07/75

1975   6   AR2-12-729   center  11/75 12/75 12/75 12/75


1976   8  AR2-12-705   center  01/76 01/76 01/76 01/76 01/76 03/76 10/76

1976   5   AR2-10-759   center  06/76


1977  13  AR2-12-705   center  01/77

1977   10  AR2-12-873     side   03/77 04/77 05/77 06/77 11/77 12/77 12/77

1977   10  AR2-12-729   center  02/77 04/77

1977   10  AR2-10-737     side   05/77

 1977   10 AR1-12-884    —–    11/77  11/77


1978   6  AR2-12-873     side   01/78 05/78 05/78 11/78 11/78

1978   1  AR1-10-919     side 03/78


1979   9  AR2-12-729   center  01/79

1979   9   AR2-12-873     side   03/79 05/79 05/79 05/79 06/79 07/79 07/79 11/79


1980   4  AR2-12-978     side   04/80 04/80 04/80 04/80


total  47

These are the surviving Motobecane carburetors that lasted longer than the rest of the bike. If there were times when the metal was weak, those months or batches would be missing from this collection, pretty much, because the ones that tended to break already broke and were thrown away. It seems like 1978 is missing some survivors, mysteriously. Perhaps they were used as upgrades/replacements for 1976-77 thin-mount ones that broke. You can see from this sub-population that early carburetors were center mount, and late ones were side mount, and in between was both.

 

 

 


Jet Drills

January 27, 2007

 

Above, a Tomos A55 idle jet (M4 thread) is physically bigger than a Puch Maxi main jet (M3.5 thread), but the hole size is much smaller. The photo shows how the #25 jet, 0.010" (ten thousandths of an inch), will allow the thinner wire of the wire wheel to pass through the hole, but not the thicker wire of the wire brush. This is a useful cleaning technique.

Above, a Tomos A55 idle jet (M4 thread) is physically bigger than a Puch Maxi main jet (M3.5 thread), but the hole size is much smaller. The photo shows how the #25 jet, 0.011″ (eleven thousandths of an inch), will allow the thinner wire of the wire wheel to pass through the hole, but not the thicker wire of the wire brush. This is a useful cleaning technique.

This will help you visualize how small these drills and jets are!

Moped main jets range from 0.018″ (#77 drill) to 0.026″ (#71 drill). 

Moped idle jets, like Tomos A55, are 0.011″ (smaller than #80).

An average human hair is 0.003″ (three thousandths of an inch).

So moped jet holes are 4 to 9 hairs wide!

Shauns well used jet drill container from the 1980's

Shaun’s well used drill container from 1987

 

Jet Drills: All through the late 1980’s and 1990’s, Shaun (at Royal Cyclery and later at Myrons Mopeds) used the USA-made jet drills to service carburetors. The drill sizes are an American wire gauge. They did not vary in size. Those 20-piece Drill Sets 61 to 80, cost $40 in 2015, $33 in 1998. and $29 in 1987. Some are in clear plastic round dome containers, and some are in conventional metal drill set boxes.

 

 

Drill Set 61-80 USA-made

Drill Set USA-made

Jet Drills made in China

Set 1 China-made

China-made Drills: In the 2000’s there were many China made tools sold in “surplus” tool stores. The China made 20-piece Drill Sets 61 to 80, sell for $7 to $10, or one fourth as much. They have an excellent blue plastic container, that only lets out one at a time. But the drill sizes are all wrong. From about 2010 to 2014, Myrons Mopeds sold these inexpensive drill sets, not knowing that the drill sizes were inexact, to say the least.

So although the China sets cost one forth as much, they only have about seven or eight different sizes, and they lack the smaller sizes below 0.4 (or sometimes 0.6) mm. Each set is different.

 

Jet Drills made in USA

Jet Drills made in USA

Set 2 China-made

Some have poorly made drills, twisted funny, bigger at the cutting end, or lumpy, varying in thickness. Some have poorly made cutting tips, so they might wander, grab and break, or not cut well.

Despite the poor quality and inexactness, the inexpensive drills are still useful for cleaning purposes, but not for measuring and maybe not for drilling. Fortunately, brass carburetor jets are the easiest thing to drill, with a drop of oil and a pilot hole already there.

 

 


Micro Drills and Wires for Sale Individually

These drills are measured at the shank (the smooth part). At the cutting edge they are 1 or 2% bigger.

These wires are steel guitar strings, cut into 5 inch lengths. 

“Metric” jets have a number that literally means hundredths of a millimeter, so a 64 jet is 0.64 mm.

Micro Drills for sale

inch   mm/#  price     moped jets that it cleans
0.011   wire     N/A Gurtner Motobecane diffuser – two idle holes (.013)
0.0135 #80  $6.00
0.0145 #79  $5.00
0.0157 0.40  $3.00 Dellorto 38 (.0162), Bing 42 (.0162)
0.016   #78  $4.00 Dellorto 40 (.0168), Bing 44 (.0167)
0.017   wire  $0.50 Dellorto 42 (.0177), Bing 46 (.0175)
0.018   #77  $3.50 Dellorto 44 (.0186), Bing 50 (.0188)
0.019   ——  $2.00 Dellorto 46 (.0194), Bing 52 (.0194)
0.0197 0.50  $2.00 Dellorto 48 (.0202), Bing 54 (.0200), “Metric” 51 (.0201)
0.0200 #76  $3.50 Dellorto 49 (.0207), Bing 56 (.0206), Gurtner 210=52 (.0210)
0.021   #75  $4.00 Dellorto 51 (.0215), Bing 58 (.0213), Gurtner 220=54 (.0220)
0.0225 #74  $5.00 Dellorto 55 (.0231), Bing 62 (.0229), Gurtner 230=56 (.0230)
0.023   ——  $2.00 Dellorto 56 (.0235), Bing 64 (.0234), Gurtner 240=58 (.0236)
0.0235 0.60  $2.00 Dellorto 58 (.0242), Bing 66 (.0239), Gurtner 245=59 (.0239)
0.0235 0.60  $1.50 Dellorto 58 (.0242), Bing 66 (.0239), Gurtner 250=60 (.0242)
0.024   #73  $3.00 Dellorto 60 (.0247), Bing 68 (.0248), “Metric” 63 (.0248)
0.025   #72  $3.50 Dellorto 62 (.0255), Bing 70 (.0254), “Metric” 65 (.0256)
0.026   #71  $4.50 Dellorto 66 (.0268), Bing 74 (.0267), “Metric” 68 (.0268)
0.0275 0.70 x N/A  Dellorto 70 (.0280), Bing 78 (.0280), “Metric” 71 (.0280)
0.028   #70  $4.00 Dellorto 72 (.0287), Bing 80 (.0287), “Metric” 73 (.0287)
0.0292 #69  $4.50 Dellorto 78 (.0306), Bing 84 (.0301), “Metric” 77 (.0303)
0.030   wire     N/A Dellorto 80 (.0312), “Metric” 79 (.0311), Gurtner K80 (.0311)
0.031   #68  $4.50 Dellorto 82 (.0318), “Metric” 81 (.0319)
0.0315 0.80  $2.00 Dellorto 84 (.0324), “Metric” 82 (.0323)
0.032   #67  $3.00 Dellorto 86 (.0331), “Metric” 84 (.0331)
0.0325  —— $2.00 Dellorto 88 (.0337), “Metric” 86 (.0339)
0.033   #66  $4.50 Dellorto 90 (.0343), “Metric” 88 (.0346)
0.034   wire     N/A “Metric” 90 (.0354)
0.035   #65  $3.00 “Metric” 92 (.0362), Gurtner MB (side mount) diffuser (.0358)
0.0354 0.90  $2.00 “Metric” 94 (.0370)
0.036   #64  $3.00
0.037   #63  $2.50
0.038   #62  $1.50
0.039   #61  $1.50
0.0394 1.00  $1.00

 


Deluxe 40-piece Micro Drill Set

Jet Drills 80-72 and 71-60

Myron’s Mopeds two case deluxe micro drill set, 80 to 72 (small) and 71 to 60 (large) plus many in-between sizes.
Price $45

Slide clear top plastic until hole is over drill (and pointer is on desired drill number). Only lets one drill out at a time. Never take out more than one at a time, or they can get mixed. The case keeps them organized. If any get lost, dull, or broken, individual drills can be bought at some hardware stores for $3-$4 each.

Useful for sizing to tell how big a jet really is (sometimes they’re drilled out or labeled wrong).

Useful for cleaning varnish or corrosion coating the inside of an old jet. It doesn’t really clean out any other way. The drill is used as a file, held with a needlenose pliers.

Useful for drilling jets to make a new size, as an alternative to buying ones. The drill is held with a needlenose pliers, and the jet is rotated with your fingers, with a drop of oil. To go down in size, fill the hole with solder and re-drill it smaller.

 

 

 

Here is a pin vise, a mini drill chuck, price $8

 

 

 

 

 

 

 


Other Tools for Cleaning Jets

Using a micrometer to measure a 0.017 wire

Using a micrometer to measure a 0.017″ wire

Guitar steel string 17 thousandths of an inch

Guitar string

Guitar Steel Strings in the smaller sizes are excellent tools for cleaning small holes. Here is a 0.0170 inch steel wire guitar string, perfect for cleaning out a 1974-85 Tomos stock jet size 46 that has a 0.0175 inch hole. A Honda Express NC50 (Keihin) carburetor, has a long brass idle jet tube with a tiny jet hole at the far end, too far for a drill to reach. For that, only a 2 or 3 inch piece of 0.010″ steel guitar string will reach to clean it. Ultrasonic cleaners, carb spray, or soaking are not effective for that. Other examples are a Sachs 52 jet 0.0190 would be cleaned by a 0.018″ wire, or a Motobecane 230 jet 0.023″ would be cleaned by a 0.022″ wire. The wire has to be a little smaller than the hole. Plain steel strings range from 0.008″  to 0.017″ in steps of 0.001″. Wound strings range from 0.017″ to 0.065″. 

 

Torch Tip Cleaner Set

Torch Tip Cleaner Set

Root Canal Files

Root Canal Files (say ahhh)

Welding Torch Tip Cleaners are another excellent tool for cleaning small holes. The tip has a cutting surface but not the sides. So it is made to clean the hole without widening it.

Wire Feeler Gauge Sets: There are also wire gauge measuring sets that look the same as the torch cleaner set shown.

Dentist’s Root Canal Files are also good for cleaning small holes. Color coded files range from 0.06 to 1.10 mm (0.0024 to 0.0433 inch).