Gurtner Carburetors

July 14, 2016

Gurtner BigContents:    1. Gurtner “Peugeot” Parts    2. Gurtner “Motobecane” Parts

                  3. Gurtner “Model 7” Parts   4. Gurtner Floats    5. Gurtner “other” 



Gurtner carburetors are made in France, and original only on the French mopeds Peugeot and Motobecane.


1. Gurtner D-type “Peugeot”Peugeot 1980 tiny

USA Versions: U1 (20mph), U2 (25), U3 (30mph) 
Left, 102 has a fixed engine and piston port intake, to cylinder. R, 103 engine swings on the swing arm pivot, case reed intake.

L, 102 has a fixed engine and piston port intake, to cylinder.
R, 103 engine swings and has a reed valve intake, to case.

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. Part no.     description        price   remarks
0   remake 103 carb w/air filter   N/A Ø12 see
1    48929 carburetor D12G-724C N/A Ø12 for 103 U2, U3
1    58036 carburetor D8.5G-826 N/A Ø8.5 for 103 U1
1b  46479 carburetor D12G-698  N/A Ø12 for 102 U3
1b  64203 carburetor D10G-975  N/A Ø10 for 102 U2
      all are Ø19 clamp-on, same as Dellorto SHA 15/15
2    48929B carb body 103 Ø12   $45 good used, bare 
2    58036B carb body 103 Ø8.5  N/A
2b  46479B carb body 102 Ø12   N/A 
2b  64203B carb body 102 Ø10   N/A
3    15319 throttle slide Ø13        see below Motobecane 18
3    69445 throttle slide Ø13       N/A for Ø8.5 (103 U1) carb
4    14107 spring Ø9.5 x 30        see below Motobecane 17
5    12156 throttle top              $10-$7
5a top assy 5,6,8,9,10,12,13   $12 used, no slide
6    14311 screw M4 x 12          see hardware M4x12 phillips
7    09939 air filter bracket         $4
7b  01088 lock washer              see hardware M4 lock washer
8    00189 adjuster M6-0.75      see cable parts A13
9    04172 adjuster nut             see cable parts A7d
10  08947 drawing rod washer     $3
11  09394 drawing rod gasket     $8-$5
12  09393 drawing rod             $18-$12
13  09391 throttle pull clip         $8 a wire “crankshaft” 
14  18892 idle screw M5-0.8     see below Motobecane 22
15  00204 idle screw spring      see below Motobecane 21
16  694xx jet 250 =MB60          $22 richer
16  69460 jet 245 =MB59          $20 for 103 U2,U3, 102 U3
16  69459 jet 240 =MB58          $15 for 103 U1
16  69457 jet 230 =MB56          $15 leaner 
16  69456 jet 220 =MB54          N/A for 102 U2
17  69300 fiber washer 19×12.5  $5 0.4mm thick, optional
18  69755 float cover w/seat     $60-$40
19  09348 rubber ring 22x27x1    $6
20  69754 plug M12-1.0             $5 taper seal, no gasket
21  08048 float cover strap        $2 for 103
21b 09365 float cover strap     $12 for 102
22  13392 screw M5 x 10         see hardware M5x10 phillips
23  06437 float w/needle          $55-$40
24  14133 fuel filter screen       see below Motobecane 28
25  09860 air box with filter       N/A for 103
26  09672 air filter gasket          $8
26b 09388 air box with filter     $40 for 102
27  09286 air filter step-screw   $20 for 103
27b 09395 air filter step-screw  N/A for 102 (use 103 type) 
28  19689 screw M3-0.5 x 6       see below Motobecane 9
29  68239 clamp bolt M6 special  $6
30  00010 clamp bolt nut          see hardware M6 nut
31  23134 mount clamp w/bolt  $10 
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.

Gurtner Peugeot remake

Gurtner Peugeot remake
see above

1980 102 SP U3 D12.698.G.1.80

’80 Peugeot 102 SP U3
says D12.698.G.1.80












2. Gurtner AR2 “Motobecane”M

7776 is pre-1978 12mm, thin stud, thin mount.
13512 is post-’78 12mm, thick stud, thick mount.
13510 is post-’78 10mm, thick stud, thick mount.

Gurtner AR212/R705 remake

AR2-12-705 remake


Gurtner AR210-R991

Gurtner AR2-10-991










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 12mm, and two styles, side or center mount. Center and side mount carbs look the same, but don’t interchange completely.

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.

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.


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.







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.

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).   


Table of Motobecane Carburetors 
complete  bare  location  intake  orig. equip  replacement  size   jet     diffuser
 part  numbers  “A or B”   pipe    ID number   ID number   mm   size    part no.        application        date range      
20026   53657  center A  short  AR2-12-705      7776**  12   54(220)  19990   30mph variator       up to 03-77
54973   54466  side(5) B   long  AR2-12-873       7776     12   56(230)  22937   30mph variator       03-77 to 12-78
54973   54466  side(6) B   long  AR2-12-873     13512     12   56(230)  22937   30mph variator       after 01-78
22160   54466  side(5) B   long  AR2-12-729       7776*   12   56(230)  21002   25 & 30 no variator  up to 12-78
22160   54466  side(6) B   long  AR2-12-729     13512*   12   56(230)  21002   25 & 30 no variator  after 01-78
52175   52430  center A  short  AR2-10-991    13510**  10       (K80)  52560   25mph variator       after 03-77
54115   54235  side(5) B   thin  AR2-10-910     13510     10   52(210)  20573   20mph no variator   up to 12-78
                                           * the only difference between a AR212/R873 and AR212/R729 is the diffuser
                                           ** the only difference is the diffuser and the float top spigot direction
Key: A = center mount carb only   B = side mount only 
New prices are green. Used prices are dark green
  pic  MB no.   description       price     remarks
   A  20026 carb Ø12  R705    $110 w/no air filter cover
   A  52175 carb Ø10  R991      N/A 
   B  54973 carb Ø12  7776   $180 w/no air filter cover
   B  54973 carb Ø12 13512   $200 w/no air filter cover
   B  22160 carb Ø12  R729    $120 w/no air filter cover
   B  54115 carb Ø10 13510     N/A see
  1A  53657 Ø12 carb bare      $65 for AR2-12-705
  1A  52430 Ø10 carb bare      N/A AR2-10-991 & 737
  1B  54466 Ø12 carb bare      $50 AR2-12-873 & 729
  1B  54235 Ø10 carb bare      N/A for AR2-10-910
  2A  18355 air filter cover      $40 for center mount
  2B  20949 air filter cover      N/A for side mount
  3A  15041 air filter screen     $12 for center mount
  3B  20999 air filter screen      $6 for side mount
  4A  18356 spring clip            $12 for center mount
  4B  M6cup cupped washer      $4 upgrade, see above
  5B  M5lock M5 nylock nut       $1 for M5 stud
  5B  M6lock M6 nylock nut       $1 for M6 stud
  5B  13339 M5 knurled nut       $2 – $1 for M5 stud
  6B  21000 stud 5mm             $5 side mount pre-79
  6B  23562 stud 6mm             $8 side mount 78-on
  6B  special M6-M5 step stud       for stripped M5 hole
  7B  20997 air filter gasket      N/A 17 x 21 x 1.5mm
  8B  20996 air filter 5mm        $8 side mount pre-79
  8B  23561 air filter 6mm       $20 can drill a 5 to 6
  9    taper screw M4-0.7 x 6/8  $1 on USA models
10    19767 bolt M5-0.8 x 44      $1 M5 w/flange 10 hex
11    15326 fiber washer 5mm   $2 5 x 10mm
12    20475 thin o-ring              $6 this is optional
       somehow, removing this often makes it leak less
13A  00189 adjuster M6-0.75    see cable parts A13
13B  21940 cable guide/elbow  $12 for side mount
14    18893 screw M5-0.8 x 12  see hardware M5x12 slot
15    01271 washer M5            see hardware M5 washer
16A  21229 slide cap M6-0.75  $12 threaded for adjuster
16B  21696 slide cap               $5 recessed for elbow
17    14107 spring Ø9.5 x 30     $5 same as Peugeot
18    15319 throttle slide Ø13  $15 for AR210 & Peugeot 
18    19278 throttle slide Ø14  $15 for AR212 carbs
19    14120 choke spring        $10
19B  22935 choke cable ring    $2 cable end adapter
20    14119 choke slide brass  $15 stepped 6.3×5.7×15
20B  22936 choke push rod      $8 original white plastic
20B  22936 substitute             see cable parts A2
21    00204 idle spring 7.5 x 11 $2
22    18892 screw M5-0.8 x 16   $2 same as Peugeot
23    00208 bolt assy M6-1.0    $5
24    00878 tall nut M6-1.0      $3 12mm tall 8mm hex
25    15043 clamp only            $2
26    23134 clamp new style    see above Peugeot 31
26A  14100 sleeve 19×16        N/A black  for AR2-10-991
26A  16630 sleeve 19×17        $25 white for AR2-12-705
26B  22689 rubber washer      $2 19 x 15 x 2mm
27    18880 float gasket          $12
28    14133 fuel filter/screen    $8 same as Peugeot
29    14101 float                     $80 – $50
30B  22937 slide diffuser Ø0.91 $40 AR2-12-873 & 978
30A  19990 slide diffuser Ø1.50 $15 for AR2-12-705
30A  20573 slide-fit diffuser Ø? N/A AR2-10-910 pre-78
30A  54237 slide diffuser Ø1.50 N/A AR2-10-910 ’78-on
30B  21002 slide diffuser Ø0.91 $35 for AR2-12-729
31    20000 collar M7-1.0         $8 holds slide-fit diffuser
32    19689 screw M3-0.5 x 7    $1 M3 taper seal
33    52560 press diffuser Ø0.61 N/A AR2-10-991 & 737
34A  21228 float top horiz inlet  N/A for center mount
34B  22161 float top vert inlet   N/A for side mount
MB carb mounts early (thin) and late (thick).

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

35    22339 float top no inlet     N/A for carb w/inlet
36    23545 jet 210cc 0.533mm $17 for AR2-10-910
36    21841 jet   #52  0.533mm N/A for AR2-10-910
36    23546 jet 220cc 0.56 mm $17 for AR2-12-705
36    21843 jet   #54  0.56 mm $20 for AR1-12
36    xxxxxx jet 225cc 0.57 mm N/A optional size
36    xxxxxx jet   xxx  0.575mm $12 drilled w/#74 drill
36    23547 jet 230cc 0.584mm $20 AR2-12-873 & 978
36    21949 jet   #56  0.584mm $22 for AR2-12-729
36    23548 jet 240cc 0.60 mm $20 for AR1-10
36    22938 jet   #58  0.60 mm $20 for AR1-10
36    23549 jet   #60  0.61 mm N/A for AR1-10
36    xxxxxx jet   xxx  0.615mm $12 drilled w/#73 drill
36    xxxxxx jet   xxx  0.64 mm $12 drilled w/#72 drill
36    51052 jet   K80  0.79 mm $22 AR2-10-991 & 737

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.

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. 

Gurtner MB bottom pull choke parts exposed

Gurtner AR2 bottom pull choke parts exposed

Gurtner MB Top pull choke cable routing

Gurtner AR2 top pull choke cable routing

Motobecane 30mph variator center-mount carb with short pipe

MB 30mph variator center-mount carb w/short pipe

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.

Motobecane 40TS has side mount Gurtner with top pull choke cable

Motobecane 40TS has side carb top pull choke

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

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





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.


Motobecane 30mph variator side-mount carb with long pipe

Motobecane 30mph variator side-mount carb with long pipe

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”. See below.

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. 








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”.   




Gurtner MB7M3. Gurtner AR1 “Motobecane 7”

pic  MB no.     description                price     remarks
0    23021 carburetor AR1-12-884     N/A for Model 7, 30mph
0    54458 carburetor AR1-10-         N/A for Model 7, 20 & 25mph
1    54454 carb body Ø12               N/A  for AR1-12-884
1    54225 carb body Ø10               N/A  for AR1-10- 
2    23194 top screw M4x22            see hardware M4x22 phillips
3    01088 washer M4 lock              see hardware M4 lock washer
4    17759 carb top                        N/A
5    14120 choke spring                  see above Motobecane 19
6    14119 choke slide                     see above Motobecane 20
7    14107 throttle spring 9.7×29     see above Motobecane 17
8a  19605 throttle slide 20 & 25         N/A
8b  16629 throttle slide Ø14 30mph   $35
9    00204 idle screw spring               see above Motobecane 21
10  18892 idle screw                        see above Motobecane 22
11  00208 bolt assy                         see above Motobecane 23
12  15043 clamp                             see above Motobecane 25
13  22689 rubber gasket                  see above Motobecane 26B
14a 23549 jet 245cc or #60 20mph   see above Motobecane 32
14b 23548 jet 240cc or #58 25mph   see above Motobecane 32
14c 23546 jet 220cc or #54 30mph   see above Motobecane 32
15  23196 air filter assy                     N/A
16  23195 air filter cover                   N/A
17  23139 screw M5x10 allen            see hardware M5x10 allen
18  14123 float                                N/A
19  14103 float gasket                      $15
20  01088 lock washer M4                see hardware M4 lock washer
21  14106 float screw M4x12            see hardware M4x12 phillips
22  19143 fuel filter                          N/A
23  15326 fiber washer 5×10             $2
24  13245 bolt M5x10                      see hardware M5x10 hex bolt
25  21940 cable guide                     see above Motobecane 13B
26  23197 air filter box                      N/A
27  19606 wood-type screw               N/A
28  19145 air box clamp                    N/A
29  23199 float chamber cap            $50
1978-79 Motobecane 7

1978 Motobecane 7

In US mopeds, this carburetor was only on one model for one year. That lone French pony was the 1978 Motobecane Model 7. This carburetor was, no doubt, also used on many 1960’s or maybe 1950’s cyclomoteurs worldwide. But in the US it is uncommon (since mopeds weren’t “welcome” until the 1970’s). Only 2 or 3% of the Motobecanes sold in the US were Model 7.   

Gurtner AR1-12 carburetor complete 3 views

Three views of the Gurtner AR1-12-884 carburetor.










4. Gurtner Floats

Gurtner Floats

Gurtner Floats

Gurtner Floats Trio

New Gurtner floats with original needle lengths and positions.









Gurtner Floats: Of the three Gurtner floats, that look like they should interchange but do not, the AR2-type 14101 (Motobecane) Gurtner #4901 is the largest, followed by the AR1-type 14123 (for MB Model 7), and the smallest D-type 06437 (Peugeot) Gurtner #6437. 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. 

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. 

Table of Gurtner Floats

Bike Models
6437 plastic 37.8 22.0 20.1 D8.5
Peugeot 102, 103, BB
Motobecane M11
brass 37.8 22.2 B10early 1950's Mobylette
13155 brass 41.5 24.0
6758 brass 41.7 22.7
5186 brass 41.5 22.5 20.3 AR10
1960's Mobylettes
3739 brass 41.7 22.5 20.3 AR1-10
Motobecane 7, Cady, Peugeot Bima
6685 brass 35.7 22.2 20.5 BA10 late 50's early 60's Mobylettes
4901 14101 plastic 41.5 24.0 20.3 AR2-10
1970's Mobylettes
40, 40T, 50S, 50V, 50VL, 50VLA
13105 plastic 41.5 25.2 20.6 AD13 1980's MBK 51, M16, 99Z 92GT


These floats can be view and purchased at in France:


5. Gurtner “other”

1962 Gurtner H17G carburetor

1962 Gurtner H17G

Gurtner early M18D M20D M22D M23.5D M25D

Gurtner 1940’s 18, 20, 22, 23.5, 25mm

Gurtner early M series article from 1945

Gurtner early M series from 1945

Here are other Gurtner carburetors, not just the 1970’s USA ones.

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






Gurtner AR10-501

1950’s Gurtner AR10-501

Gurtner AR10-511

1950’s Gurtner AR10-511

A, AR, B, BR series
(1949-59 Mobylette)

A10-512 for Mobylette
B10-516 for Mobylette Service
AR8.7-525 for Mobylette BG
AR10-511 for Mobylette
AR10-501 Moby. with variator
BA10-540 Moby. with Dimoby
BR10-515 Moby. with Dimoby



Before 1960, all (or almost all?) 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.

BA series (1959-65? Mobylette)

Gurtner BA540 and 549

Gurtner BA10-540 (BA540) and 549

Gurtner BA540F2 left

BA540 left

Gurtner BA540F2 top

Gurtner BA540 top








Gurtner BA540F2 front

BA540 is 10mm

Gurtner BA540F2 back

1962 Riverside, BA540-F 2/62











1964 AU65 with Gurtner BA610

1962 Motoconfort AU65 with Gurtner BA610

1963 Raleigh RM6 with BA610

1963 Raleigh RM6 with BA610











1962-63 AV48 with Gurtner BA610

1962 AV48 with
 BA610-C 10/63

BA610 front

BA610 front

BA610 left

BA610 is 10mm

BA610 right

BA610 right









Gurtner 6685 Float

Gurtner 6685 flotteur is 22.2 x 35.7mm

Gurtner float gaskets 23 and 25mm

Float gaskets 23 and 25mm ID










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



AR13 series (1960-62? Mobylette)

Gurtner AR13-488 parts (for AV87)

Gurtner AR13-488 parts (for 1961 AV87)














MB Cady Gurtner AR1

MB Cady Gurtner AR1

MB Cady and MB 7 air boxes

Motobecane Cady versus Motobecane 7










Table of Gurtner Carburetors

Carb Model Venturi
Bike Model Float
MB #
Float Size Float
D12G-724C 12mm 19mm 1976-80 Peugeot 103 6437 22.0 x 37.8
23.4mm 13mm
10mm 19mm 1957 Mobylette AV78 5186
22.7 x 41.4
23.9mm 13mm #21
13mm 19mm 1959 Riverside Mo-Ped 5186
22.7 x 41.4
23.9mm 14mm
10mm 19mm 1960 Mobylette 6685A 22.2 x 35.7
23mm 13mm #19
10mm 19mm 1962 Riverside Mo-Ped 6685A 22.2 x 35.7
23mm 13mm #20
10mm 19mm 1963 Mobylette 13mm
10mm 19mm 1962 Mobylette AV48 mystery 22.3 x 37.4
13mm #19
12mm 19mm 1978 Motobecane 7 5186
22.7 x 41.4
23.6mm 14mm
7/75 to 1/77
12mm 19mm 1975-77 Motobecane 50V
(30mph version)
23.6 x 41.4
25.2mm 14mm
03/77 to 11/79
12mm 19mm 1977-79 Motobecane 50V
(30mph version)
23.6 x 41.4
25.2mm 14mm
03/77 to 11/79
10mm 19mm 1977-79 Motobecane 50V
(25mph version)
23.6 x 41.4
25.2mm 13mm
13mm 19mm 19xx Motobecane SP94 4901
23.6 x 41.4
25.2mm 14mm
13mm 19mm 1983 Motobecane


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   5  AR2-12-873     side   01/78 05/78 05/78 11/78 11/78

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  $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).