Carburetor lugs down

Robert Hollingsworth /

We have a Motobecane with a Dellorto 14 12 carb. It starts fine and runs fine except: it only wants to run (when riding) when the choke is held at half-choke. When you let go of the choke lever, the bike lugs down and only chugs along or stops. Any ideas?

Re: Carburetor lugs down

Clean the carb thoroughly .

Everything inside the carb has to be pristine .

Re: Carburetor lugs down

ensure theres no air leaks. ensure the main jet is appropriatly sized.(mid to high 50's) ensure the idle jet (below slide) is clear.

Re: Carburetor lugs down

♣Slew Foot♣ /

Check your intake mounting it does sound like you have an air leak cover it the intake and kick it over and see if it still runs or have it running and just cover the whole thing with your thumb and listen for a hiss the air leak may even be a d compressor leaking or loose cylinder head so check it all out

Re: Carburetor lugs down

Did the bike come with that carb? Did you put it on? If so, did you re-jet the carb accordingly? Sounds lean to me...

Also, never heard of using a 14/12 on a Moby. I always used a 15/15 to avoid restriction.

Re: Carburetor lugs down

SHA 14:12 is a normal straight exchange carb for the Gurtner, for a stock AV7 you need a 53 jet.

Check for leaks at the carb to intake union, the shim there should only be to get the carb to grip properly, for a proper seal throw in a 5/8 x 13/16 x 3/32 oring.

Give the motor a leak down test (not by spraying aerosol shyte around the motor but a proper one) to check if the spi seals or gaskets on the engine are leaking. Get a new crush gasket for the exhause and remove the exhause and give it a goodly clean out.

Check the timing, best running is with it set at 0,4mm at index and initiation at 1,5mm BTDC.

Re: Carburetor lugs down

Oh wow thanks for the info man. Always thought that the 15/15 was the go to. Then again I wasn't concerned about direct replacement.

Re: Carburetor lugs down

SHA15:15 with a 15mm intake is the gateway drug of Frenchie performance...

...there is no turning back after that...

Frenchmopedsink.jpg

> Aaron Blair Wrote:

> -------------------------------------------------------

> Oh wow thanks for the info man. Always thought that the 15/15 was the go

> to. Then again I wasn't concerned about direct replacement.

Re: Carburetor lugs down

Sounds like the jet is way too much for it. Bet its a 62-68 in that 14 12 .

« Go to Topic — end of thread

Want to post in this forum? We'd love to have you join the discussion, but first:

Login or Create Account