Dellorto Carburetors

December 24, 2014

Contents:   1. Dell’Orto “SHA”   2. Dell’Orto “SHA Vespa”     3. Dell’Orto Jets

4. Dell’Orto SHA Service   5. Dell’Orto “PHVA Tomos”

Brief History: Dell’Orto is an Italian company, headquartered in Cabiate, specialized in the construction of carburetors and electronic fuel injection (EFI) systems. The company was founded in 1933 as “Società anonima Gaetano Dell’Orto e figli” (Gaetano Dell’Orto and Sons). Their first products were carburetors that came fitted as standard to new vehicles. Shortly before the second world war they began producing carburetors with aluminum bodies for use in motorcycle racing. At the beginning of the 1960s Dell’Orto was producing OEM carburetors for the Fiat group, as well as other Italian and foreign constructors (i.e.Flandria, Belgium). At the end of the 1980s, under the supervision of Luigi Dell’Orto (son of Gaetano), the company’s first injection systems were released. The company is today one of the worldwide leaders in the field of carburation and is present in the sport field as partner of Gilera that participates in the Road Racing World Championship. It is also used in every modern Derbi, Aprilia, and Yamaha 50cc model. (from Wikipedia).

 

Welcome. Dellorto carburetors are on virtually every Italian motorcycle made since 1950. Some carburetor parts like screws and jets are the same for a whole range of carburetor styles and/or sizes. So the exact millimeter sizes are included in the parts descriptions. By knowing the millimeters and thread pitches, you can find screws and parts for anything from carburetors to telescopes.

Dellorto Metric Threads: The way a screw or bolt is described here (the syntax) is “thickness dash thread width times shank length”. So an M6-1.00 x 20 bolt is just under 6mm thick, each thread is 1.00mm wide, and the length below the head is 20mm.

Bolt Size >       3mm  4mm   5mm   6mm
regular pitch     0.50   0.70    0.80   1.00       So the Dellorto M4 is coarser (threads farther apart) than normal M4
Dellorto pitch    0.50   0.75    0.75   1.00       and the Dellorto M5 is finer (threads closer together) than normal M5 

Many carburetor bodies get ruined or “stripped” by using the wrong screws. 

1. Dell’Orto “SHA”

The Dellorto SHA is a family of Italian moped or mini-bike carburetors. They all have the same outer size and main body appearance, with a 59mm round flange for an air filter. They have been produced for in Italy from the 1960’s to the 2000’s. In particular the Dellorto SHA 14/12 and 14/9 carburetors were on tens of thousands of US mopeds from 1976 to 1985. The Spanish moped Derbi had Arbeo-Dellorto carburetors, made in Spain under license. They were more goldish colored, and tended to leak fuel past the float seat. Since the 2000’s there are Asian remakes.

Carburetor Size: The venturi is where the air mixes with gasoline. It is also where the air passage gets narrower, to cause a higher air speed in order to atomize or break up the liquid fuel into smaller droplets. With Dellorto SHA carburetors, two numbers are used to describe the size of the venturi. The first number is the venturi exit, and the second number is the venturi entrance. So looking at an SHA 14/12 from the front you see a 12mm hole, and from the back (engine side) you see a 14mm hole.

Choke Type: The choke is a lever you push or pull, “on” for cold starting, or “off” for normal running. There are three types used on Dellorto SHA carburetors:

A   direct lever   – push down lever on carb to put choke “on”, give full throttle to release it “off”
B   linkage lever – same operation as direct lever
C   cable choke  – cable goes to a handlebar thumb lever, pull to put choke “on”, let go for “off”    

pic    carburetor      choke  price  size clamp   remarks 
A  SHA 14/9   Italy    lever   N/A    Ø9  Ø20 
 SHA 12/12 Spain   lever   N/A   Ø12  Ø20 Derbi 76-85 Variant
A  SHA 14/12  Italy   lever   N/A   Ø12  Ø20
A  SHA 14/14  Italy   lever   N/A   Ø14  Ø20
B  SHA 14/12P Italy linkage  $80  Ø12  Ø20 86-06 Tomos A3/A35
C  SHA 15/15C Italy  cable $100  Ø15  Ø21
C  SHA 16/16C Italy  cable   N/A  Ø16  Ø21
C  SHA 12/12C Spain cable   N/A  Ø12  Ø20 Derbi 86-89 Var. Sport

Carb top threads are M6-0.75. Adjuster threads are M5-0.75. Except 2d, a throttle cable 3mm end can pass through these.

 

 

 

 

 

 

 

 

 

 

 

 

 

pic #         description                  price        remarks
1    219624 rubber boot for cable     $2
1
   
modern rubber boot long x  xx   $2 
2    222222 adjuster M6 – 0.75        see cable parts A13
2a vintage curved pipe 22×30 90º $15 adjuster 3a not included
2b vintage curved pipe 20×28 90º $15 adjuster 3a not included
2c modern curved pipe long 70º      $6 adjuster 3a not included
2d vintage curved pipe long 70º      $7 Derbi type uses step ferrule
2e vintage curved pipe short 35º   $10 Garelli type no adj. threads
2f vintage curved pipe short 40º   $15 Garelli VIP no adj. threads
2g modern curved pipe 30×27 90º  $5 adjuster 3a not included
2h modern curved pipe short 60º    $5 adjuster 3a not included
3    222222 carb top nut M6 – 0.75  $2
3a  219625 adjuster & nut M5-0.75 $5 not regular metric M5-0.80
3b  222222 adjuster nut M5-0.75    $3 not regular metric M5-0.80
4    219598 screw M4-0.75×14 flat  $2 not regular metric M4-0.70
5    222222 washer M4                  see hardware M4 washer
6    222222 carb top bare               $5
6a  219596 carb top angled hole    N/A Tomos
6b  222222 top assy 6,7,8,9,10     $20
7    219871 hinge pin choke (in top) $2
7    222222 future use
8    219872 spring choke (in top)     $2
9    219873 lever choke trigger        $5
10   219583 gasket for carb top      $3
11   219874 spring throttle return  $10
12   219580 slide throttle valve     $10
13   222222 screw M5-0.75 x 15     $8 not regular metric M5-0.80
14   219780 seal washer 5 x 10       $1
15   219584 banjo inlet metal 3/16 $15
15a 219584 banjo fuel inlet plastic   $8
15b 222222 banjo inlet metal 1/4″  N/A put a thin hose over 15a
16   219585 filter fuel plastic mesh  $5
17   222222 nut M6 early type         $2 most have regular nut
18   219590 gasket for air filter      N/A these are all too brittle
19   219591 spring for choke plate   $3 for all types A, B, C
20   222222 plate with lever short   $7 type A “lever choke”
20a 222222 plate with lever med.   $7 type A, for hard to reach
20b 222222 plate with lever long    $7 type A, Cimatti type
21   219592 pivot step-bolt choke   $3 for all types A, B, C 
22   219593 hinge pin Ø2.0 x 16.5   $2
23   222222 intake sleeve 16 x 20  see below for prices and sizes
24   222222 clamp bolt M6-1.00     $2 
25   219587 idle screw M4-0.70×25   $4 regular metric M4-0.70
26   219588 spring idle Ø4,Ø6 x 12   $2 
27   219589 float needle valve      $10
28   222222 jet M5-0.75 thread    see below Dellorto Jets
29   219582 float all white plastic  $18-$12
30   219594 gasket rubber ring       $3 all new ones are round
31   222222 float bowl metal          $5
32   222222 screw M4-0.75 x 18      $5 not regular metric M4-0.70
33   222222 clamp w/nut M4-0.75   $5 
34   222222 screw M4-0.75 x 25     N/A re-thread nut to use #8-32

39. Aftermarket air filter for Dellorto SHA
Compact enough to fit 1996-2006 Tomos

35   222222 air filter metal screen  $12
36   222222 air box small thin type $15 does not have the 2 tubes 40
37   222222 air box large thick       $18 does not have the 2 tubes 41
38   222222 air box Minarelli type   $15 new Malossi aftermarket

38   222222 air box Minarelli type   $25 used original #5660
39 6090813 air filter aftermarket    $22 this needs a bigger jet
40   222222 restrictor tube small       $7
41   222222 restrictor tube large     $8
43   222222 choke plate cable type N/A type C
44   223025 pivot shaft w/linkage    $6 type B
45   223027 spring for pivot shaft    $2 type B
46   222222 plate linkage w/post    N/A type B, this gets rounded
47   223028 choke lever external     $8 type B, this gets hourglass shape
48   222222 lock washer M3           $1 type B, better to weld 46,47,49
49   222222 nut M3-0.50               $1 type B, better to weld 46,47,49
50   222222 gasket set 3 piece       $6

Tomos Parts
51 xxxxxx 1986-95 A3+A35 junction sleeve xxxx
52 xxxxxx 1986-95 A3+A35 air box xxxxxxxxxxx
53 xxxxxx 1986-95 A3+A35 inlet tube xxxxxxxxx
54 xxxxxx 1986-95 A3+A35 inlet tube snorkel xx
55 xxxxxx 1996-06 A35 junction sleeve xxxxxxxx
56 xxxxxx 1996-06 A35 inlet grommet xxxxxxxxx
57 xxxxxx 1996-06 A35 air box assy 57,58,59 xxx
58 xxxxxx 1996-06 A35 air box screw xxxxxxxxx
59 xxxxxx 1996-06 A35 air filter foam xxxxxxxxx
60 xxxxxx 1986-91 A3 intake screw xxxxxxxxxxx
61 xxxxxx 1986-91 A3 intake screw xxxxxxxxxxx
62 xxxxxx 1986-91 A3 washer 6mm xxxxxxxxxxx
63 xxxxxx 1986-91 A3 center intake xxxxxxxxxxx
64 xxxxxx 1986-91 A3 intake gasket thin xxxxxxx
65 026566 1992-95 A35 allen screw M5x20 xxxx
66 031931 1992-95 A35 washer 5mm xxxxxxxxxx
67 xxxxxx 1992-95 A35 center intake xxxxxxxxxx
68 223748 1992-06 A35 reed valve gasket xxxxxx
69 222238 1992-06 A35 reed valve xxxxxxxxxxxx
70 229707 1996-06 A35 side intake (no oil inject.)
71 229716 1996-06 A35 side intake (oil injection)

 

 

 


Table of Intake (Clamp) Sizes and Intake Sleeves  

 #   intake   sleeve    price      applications

   16mm  16 x 18    see below Dellorto Vespa
23  16mm  16 x 20     $4 Morini MO1, MO2, Verona, Demm, Tomos 76-85, Batavus M48
   16mm  16 x 20         more apps to follow…
   17mm  17 x 19    see Gurtner Motobecane  Motobecane center-mount
23a 18mm  18 x 20     $7 Minarelli, Garelli, Tomos 85-06, Morini M1
23b 18mm  18 x 21     $7 for SHA15/15 and 16/16 aftermarket carbs
23c 19mm  19 x 21     $7 Peugeot, Motobecane
    20mm no sleeve       Puch, Sachs


 

Choke Sticking On: Often the choke sticks on, for no apparent reason. The throttle cable is sometimes too loose to pull up the choke trigger. More often, the choke trigger lever has become bent or twisted. This happens often because great care must be taken to keep the trigger against the side wall when the top assembly (throttle slide, choke trigger, cover assembly) is installed. Before the top screws are tightened, and with one finger holding the top in proper position, it is wise to test the choke by directly pulling on the throttle wire. It should click off at full throttle. Only then should the screws be gently tightened, while holding the top with that finger. If not, then inspect the trigger lever for misalignment, and re-align carefully with small pliers. Sometimes rounding off the side edges helps the trigger lever to not stick also. The last resort is to replace it, but pushing out the tiny hinge pin is difficult. So it is better to straighten it.  

 


2. Dell’Orto “SHA Vespa”

Welcome. The Dellorto “SHA Vespa” is like a regular “SHA” but more compact. It has a smaller 50mm air filter flange, not 59. This style of carburetor was original on all Vespa/Piaggio mopeds 1970’s, 1980’s, 1990’s, and 2000’s. In the USA it was on 1972-86 Vespa mopeds, 1983-86 Garelli VIP-N, and mid 1990’s Kinetic TFR mopeds. 

The SHA Vespa carburetor has an improved choke release trigger, that cures the sticking trigger lever problem that the regular early SHA had. Vespa types have a sliding push rod, that moves up a ramp in the throttle slide when the throttle is raised fully. The solid rod pushes the choke lever/plate over a little stop tab. The torsion spring is then free to snap it back off. The top is relatively easy to put on, with only the throttle slide and spring to install, no choke device that gets damaged easy, not even a top gasket.

 

There were 3 carb bodies, 7, 10, and 12mm, 5 jet sizes, 39, 41, 43, 45, 49, and 2 air filter boxes, 3-hole and 6-hole.
The Boxer had a side-pull carb top assy, like Peugeot. It gives more frame clearance. After 1979 the Boxer became the Si. 
There were 4 choke levers, Grande, Bravo, Ciao, Boxer. The later Boxer 2 had the linkage type choke with pull wire.

 

1980s Vespa Carburetors

There are 3 carb bodies, 7, 10, and 12mm, 4 jets, 39, 42, 45, 49.
The Ciao P and Bravo P had top pull, and Si had a side-pull carb top assy.
There are 3 choke levers, Bravo-Ciao, and Si, linkage type, and Grande.
There are 2 air filter boxes, 3-hole and 6-hole. Some are newer designs.

 

Prices in green are for new, dark green are for used items.

pic# Vespa #      description        price      remarks

SHA12.12 Vespa bare body           $70  Grande 25 & 30mph
SHA12.10 Vespa bare body           $50  Ciao, Bravo, Si 25 & 30mph
SHA12.7  Vespa bare body            $60  Ciao, Bravo, Grande, Si 20mph

1  098128 cable adjuster M5-0.75  see above Dellorto 3a
2  120074 lock nut M5-0.75           see above Dellorto 3b
3  113903 elbow 90º M6-0.75        see above Dellorto 2a
4  120073 lock nut M6-0.75           see above Dellorto 3
5  113906 screw M4-0.75×14 flat    see above Dellorto 4
6  113902 carb top top-pull type     $12  there’s no carb top gasket
7  113901 spring throttle Ø11 x 26  $10
8  135734 throttle slide 21x26x3    $15 also has a ramp to release choke 
9  124753 rubber washer 2x7x1.5   $3 slides into a pocket from the side
10 124598 slide rod Ø2 x 35          N/A like Peugeot (28mm) but bigger
11 124597 rocker arm Ø5 hole       N/A
12 092403 step bolt Ø5/M4-0.75    N/A Ø5 x 2 step, M4-0.75 x 10 shank
13 016320 thin washer M5             see hardware M5  thin washer
14 014404 lock washer M4             see hardware M4 lock washer
15 012012 nut M4-0.75                 N/A not a regular M4-0.70
16 124752 screw M4-0.75×10 sunk N/A can substitute a flat head
17 098130 spring Ø5 x 7 x 12          $3
18 098128 cable adjuster M5-0.75  see above Dellorto 3a
19 124596 carb top side-pull type  N/A  above this line “carb top” assy
21 133921 choke lever Ciao            $6 below this line “bottom” assy
22 353882 choke lever Grande       $15
23 140342 choke lever Bravo         $17 very long
24 113917 inlet bolt M5-0.75 x 18  $10 can not be normal M5-0.80
25 082920 seal washer 5 x 8           $3 can not be normal 5 x 10
26 113914 banjo fuel inlet            $10-$5
27 113916 fuel filter  Ø11 x 8         $12-$7
28 113915 seal washer 11 x 16         $8
29 114482 intake sleeve 16 x 18     $25 smaller than 20mm, regular SHA
29 222222 rubber washer 12x18x2  $2 not for 70’s Vespa moped
30 113926 bolt M6-1.0 x 20            $5 special small head
31 113927 thin nut M6-1.0             see hardware M6 thin nut
32 113923 spring for choke plate     $4 torsion spring
33 113922 pivot bolt choke            $4 shoulder bolt
34 098135 spring for idle screw       see above Dellorto 26
35 113919 idle screw M4-0.70         see above Dellorto 25
36 164149 choke pull rod               N/A Bravo P, Si
37 188772 choke pull rod               N/A Ciao P
38 186413 coupling pipe (clip)        N/A Si, Ciao P, Bravo P
39 212930 bracket                       N/A Bravo P
40 188164 bracket                       N/A Ciao P
41 164147 choke plate long flat      N/A Si
42 188162 choke plate short bent   N/A Ciao P, Bravo P
43 main jet M5-0.75 thread           see below Dellorto Jets 
     120519 jet 39    20mph 1978-on Ciao, Bravo, Grande, Si, Ciao P
     135233 jet 41    25mph 1980-83 Si, 30kph(19mph) 1984-on Bravo P
     191125 jet 42    25mph 1980-on Ciao P
     113912 jet 43    30mph 1980-on Si, 1968-77 Ciao, 1972-77 Bravo
     130525 jet 45  30 & 25 1978-83 Ciao, Bravo
     158780 jet 49  30 & 25 1978-85 Grande, 30mph 1984-on Ciao P, Bravo P, Si

Vespa air filters L, 3-hole, R, 6-hole. Row 1 covered: L Kinetic, R Grande. Row 2 open: L, Ciao, R, Ciao P

Vespa air filters: L, 3-hole, R, 6-hole.
Row 1 covered: L, Kinetic, R, Grande.
Row 2 open: L, Ciao, R, Ciao P

44 090506 float needle             see above Dellorto 27
45 113910 float all plastic           $35-$25 says 2.5 grams 7420.1
46 113909 gasket float bowl          see above Dellorto 30
47 085291 hinge pin Ø2.0 x 16.5  see above Dellorto 22
48 113908 float bowl metal           $12 – $7
49 098134 bowl screw M4-0.75×18  see above Dellorto 32
50 131009 air filter screen              $15
51 113055 clamp air filter w/screw  $12
52 000000
53 113347 air filter 3-hole open       $35 68-80 Ciao, Bravo (20,25,27)
54 306922 air filter 6-hole covered  $50 78-86 Grande (20, 25, 30)
55 183423 air filter 6-hole open       $60 81-86 Ciao PX (30mph)
56 186886 air filter 3-hole open      N/A 80-86 Si, Ciao PX (20, 25)
57 000000 air filter 3-hole covered  $40 95-99+ Kinetic TFR
58 000000


 


3. Dell’Orto Jets

Below is the actual sizes of Delorto 5mm jets, obtained by direct measurement. You can see the line has a different slope for the bigger sizes than for the smaller ones. You can also see what drill sizes correspond to what jet sizes.

42 0.01xx”=0.xxx   $5
43
0.0182″=0.462  N/A pre-78 Ciao & Bravo
44 0.01xx”=0.4xx    $5
45 0.0190″=0.483  N/A 78-on Ciao & Bravo
46 0.01xx”=0.4xx    $5
47 0.0198″=0.503    $8
48 0.0202″=0.513    $5
49 0.0207″=0.525    $8 78-on Vespa Grande
50 0.0210″=0.533    $5 76-80 Garelli (some)
51 0.0215″=0.546    $8 85-91 Tomos A3
52 0.0219″=0.556    $5 ALL OTHERS 30mph
53 0.0223″=0.566  N/A 92-06 Tomos A35
54 0.0227″=0.577    $5
55 0.0231″=0.587  N/A
56 0.0235″=0.597    $5
58 0.0242″=0.615    $5
60 0.0247″=0.627    $5
62 0.0255″=0.648  N/A
64 0.0262″=0.665  N/A
66 0.0268″=0.681  N/A
68 0.0274″=0.696  N/A
70 0.0280″=0.711  N/A

 


4. Dell’Orto SHA Service

 

The Dellorto SHA idle hole is in the silver zinc body, at the base of the brass spray tube

Cleaning a Dellorto idle hole with a tiny #71 drill and a pin vise

Cleaning a Dellorto idle hole with a tiny #71 drill and a pin vise

 

 

 

 

 

 

 

 

Here is the engine side view of a Delorto SHA carburetor. At the base of the vertical brass “spray tube” with one or two holes in it, there is a tiny hole in the silver metal below the brass. It gets overlooked frequently. When it is blocked, the engine will not stay idling for more than a few seconds, but will otherwise run fine if the throttle is kept open.

 

 


5. Dell’Orto PHVA14

Welcome. This is a “third generation” Tomos carburetor, on US mopeds. It is preceded by two others, the Encarwi A83 on Tomos A3 1974-85, and the Dellorto SHA 14-12P on Tomos A3 1986-91 and A35 1992-06.

 

Dellorto PHVA14 Tomos A55 carburetor four views

 

Dellorto PHVA14 parts

0    233730 Carburetor PHVA 14 DD  N/A right side, no drain
1    243115 Rubber Boot for cable      see above Dellorto SHA 1
2    243116 Adjuster w/nut M5-0.75   see above Dellorto SHA 3a+3b
3    243152 Throttle Cable Guide 72º  see above Dellorto SHA 2c
4    243118 Screw M5-0.80 x 14        see hardware M5 x 15 screw
5    243119 Carburetor Top Cover      N/A
6    set only Rubber “figure 8” gasket  N/A see 40 below
6    T
he wrong one, paper kind, is shown. Actual Tomos kind is rubber.
7    243120 Throttle spring Ø12 x 52   N/A
  243121 Throttle slide insert         N/A
9    243103 Throttle Slide #40 Ø15    N/A
10  243122 E-clip 1.5mm for needle     $2 1.3 at opening, for 1.5 groove
10a 222222 Substitute E-clip 1.5mm    $2 1.3 at opening, for 1.5 groove
11  243104 Needle A07 2.0-1.0 x 38  $30 2.0mm needle, 1.5 clip groove
Dellorto PHVA throttle needle and substitute11a 222222 substitute 2.0-1.1 x 38     $8
12  ——————————————-
13  243125 Choke Lever bare            N/A
14  choke o-ring rubber o-ring 18 x 20  $4
15  243123 Screw M4-0.70 x 10       see hardware M4 x 10 screw
16  243124 Clamp for choke lever      N/A
17  243151 Choke Assy 13,14,15,16 N/A
18  243126 Spring Idle Air Ø5,Ø7 x 9   $8
19  243147 Idle Air Screw M5-0.50    $18
20  future use
21  243128 Spring for Idle Ø5,Ø7 x 14 $8
22  243148 Idle Spd. Screw M5-0.80  $18
23  243106 Needle Housing 209GA     $17
23a 222222 Needle Housing 210GA    $15
24  243160 Main Jet M6-0.75 size 55  N/A original A55 size #55
24a D64-052 main jet M6-0.75 #52   $10 smaller for high altitude
24b D64-058 main jet M6-0.75 #58   N/A bigger
24c D64-060 main jet M6-0.75 #60   N/A bigger
26  243222 Idle Jet M4-0.70 size 25   $15 original A55 size #25
26a D11600x29 idle jet M4-0.70 #29   $12 bigger
26b D11600x30 idle jet M4-0.70 #30  $12 bigger
26c D11600x32 idle jet M4-0.70 #32    $7 bigger
26d D11600x40 idle jet M4-0.70 #40    $7 way bigger
28  243162 Choke Jet M5-0.80 #40      $5 regular metric thread
30  243114 Float all plastic bare         $25
31  243149 Float w/Needle Valve        $45
32  243131 Float Needle Valve           $35

Dellorto PHVA Gaskets

Dellorto 52622 PHVA Gasket Set
Right: 6,14,34    Left: others

34  set only Rubber o-ring                  N/A bigger than SHA one
3
5  243132 Hinge Pin Ø2.0 x 19.5        $7
36   243150 Float bowl plastic            N/A
37  027057 Screw M4-0.70 x 18         see hardware M4 x 18 screw
40  236460 Gasket set 6,14,34 only     $20
40    52622 Gaskets 6,14,34 +others  $25
    others Gaskets others only         $10
45  233740 Intake silencer assy
46  233741 Air Filter Foam
47  233748 Junction sleeve
48  221584 Clamp 32-50

 

 


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  $3.50
0.0145 #79  $3.50
0.0157 0.40  $2.00 Dellorto 38 (.0162), Bing 42 (.0162)
0.016   #78  $3.00 Dellorto 40 (.0168), Bing 44 (.0167)
0.017   wire  $0.50 Dellorto 42 (.0177), Bing 46 (.0175)
0.018   #77  $3.00 Dellorto 44 (.0186), Bing 50 (.0188)
0.019   ——  $1.50 Dellorto 46 (.0194), Bing 52 (.0194)
0.0197 0.50  $1.50 Dellorto 48 (.0202), Bing 54 (.0200), “Metric” 51 (.0201)
0.0200 #76  $1.50 Dellorto 49 (.0207), Bing 56 (.0206), Gurtner 210=52 (.0210)
0.021   #75  $3.00 Dellorto 51 (.0215), Bing 58 (.0213), Gurtner 220=54 (.0220)
0.0225 #74  $1.50 Dellorto 55 (.0231), Bing 62 (.0229), Gurtner 230=56 (.0230)
0.023   ——  $1.50 Dellorto 56 (.0235), Bing 64 (.0234), Gurtner 240=58 (.0236)
0.0235 0.60  $1.50 Dellorto 58 (.0242), Bing 66 (.0239), Gurtner 250=60 (.0242)
0.024   #73  $1.50 Dellorto 60 (.0247), Bing 68 (.0248), “Metric” 63 (.0248)
0.025   #72  $3.00 Dellorto 62 (.0255), Bing 70 (.0254), “Metric” 65 (.0256)
0.026   #71  $3.00 Dellorto 66 (.0268), Bing 74 (.0267), “Metric” 68 (.0268)
0.0275 0.70  $1.50 Dellorto 70 (.0280), Bing 78 (.0280), “Metric” 71 (.0280)
0.028   #70  $1.00 Dellorto 72 (.0287), Bing 80 (.0287), “Metric” 73 (.0287)
0.0292 #69  $2.50 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  $1.00 Dellorto 82 (.0318), “Metric” 81 (.0319)
0.0315 0.80  $1.00 Dellorto 84 (.0324), “Metric” 82 (.0323)
0.032   #67  $0.75 Dellorto 86 (.0331), “Metric” 84 (.0331)
0.0325  —— $1.00 Dellorto 88 (.0337), “Metric” 86 (.0339)
0.033   #66  $2.50 Dellorto 90 (.0343), “Metric” 88 (.0346)
0.034   wire     N/A “Metric” 90 (.0354)
0.035   #65  $1.00 “Metric” 92 (.0362), Gurtner MB (side mount) diffuser (.0358)
0.0354 0.90  $1.00 “Metric” 94 (.0370)
0.036   #64  $2.50
0.037   #63  $2.50
0.038   #62  $1.00
0.039   #61  $0.75
0.0394 1.00  $0.75

 


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 $2-$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.

 

 

 


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).