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.
USA Versions: U1 (20mph), U2 (25), U3 (30mph) 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 treatland.tv 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
2. Gurtner AR2 “Motobecane”
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.
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 1977mopeds.com 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 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.
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.
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.
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.
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.
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”.
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
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.
4. Gurtner Floats
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
|Peugeot 102, 103, BB|
|brass||37.8||22.2||B10||early 1950's Mobylette|
|Motobecane 7, Cady, Peugeot Bima|
|6685||brass||35.7||22.2||20.5||BA10||late 50's early 60'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 lesolex.com in France:
5. Gurtner “other”
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.
Read more at mopedarmy.com
A, AR, B, BR series
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)
Most of this information and photos are from the Motobecane Club of France.
AR13 series (1960-62? Mobylette)
Table of Gurtner Carburetors
|D12G-724C||12mm||19mm||1976-80 Peugeot 103||6437||22.0 x 37.8|
|10mm||19mm||1957 Mobylette AV78||5186|
|22.7 x 41.4|
|13mm||19mm||1959 Riverside Mo-Ped||5186|
|22.7 x 41.4|
|10mm||19mm||1960 Mobylette||6685A||22.2 x 35.7|
|10mm||19mm||1962 Riverside Mo-Ped||6685A||22.2 x 35.7|
|10mm||19mm||1962 Mobylette AV48||mystery||22.3 x 37.4|
|12mm||19mm||1978 Motobecane 7||5186|
|22.7 x 41.4|
7/75 to 1/77
|12mm||19mm||1975-77 Motobecane 50V|
|23.6 x 41.4|
03/77 to 11/79
|12mm||19mm||1977-79 Motobecane 50V|
|23.6 x 41.4|
03/77 to 11/79
|10mm||19mm||1977-79 Motobecane 50V|
|23.6 x 41.4|
|13mm||19mm||19xx Motobecane SP94||4901|
|23.6 x 41.4|
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
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.