gas leak (motobecane)

when I open up the fuel shut off valve, gas enters the carb and overflows from the top and bottom of the float bowl. when i start up the engine the leak becomes a trickle from the jet at base of the carb. I've had the carb off and checked the tightness of the casing screws. everything is snug. any ideas??

Re: gas leak (motobecane)

I have the same problem with my Cady(Gurtner carb), hopefully someone has an answer for this?

Re: gas leak (motobecane)

the float operates just like an old style toilet .. the float rises, when it reaches the proper pre-set level, pushes a shut-off valve closed.

This carb's float's valve is called the float needle. If it or it's seat is damaged or dirty, fuel will not shut off .. will continue to rise in the bowl and either leak out somewhere or rise until it comes out of an overflow tube.. or both.

Re: gas leak (motobecane)

oops.. i keep forgeting that motobecane carbs are slightly different.. but the principle is the same.

"Search" this forum with the search link ..

use the words "motobecane carb leak" (or similar)

select Message Bodies

drop down arrow to 'All Dates'

a lot of threads turn up..

Re: gas leak (motobecane)

The float in your float valve is probably stuck. Dissasemble the entire carb, clean it and put it back together.

Re: gas leak (motobecane)

The gas leaking from your float bowl and the gas leaking from the jet at the bottom sound like two different problems. I was blessed with a carb with a good float and needle valve, so I can't help you there, but I do have some experience with the leaking jet. There is no gasket or anything between the brass jet and the bottom of the carb; Gurtner just relied on the harder brass jet mashing into the softer metal of the carb body and forming a good seal. It works once or twice, but after you take it apart a couple of times it doesn't seal so well. I just wrapped the base of the jet several times with teflon tape (taking care not to cover the inlet holes) until the leaking stopped.

Re: gas leak (motobecane)

Thanks far all the help -- I'm off to clean and tape>

Re: gas leak (motobecane)

I've had a simular problem with mine however after cleaning several time I found that my float is sluggish to rise to the shutoff point and to compound matters my fuel shut off valve doesn't want to stinch the flow of fuel completly. I've ordered some replacement part from the mopedjunkyard.com

Re: gas leak (motobecane)

I would not try the tape untill you fix the float. Gas that appears to be leaking from the bottom of the jet is usually leaking from somewhere else. I have had alot of leaky gurtners, and I always suspected that jet, but it was always leaking from somewhere else Is the paper gasket (figure 8 shaped)still intact?

you can reshape the needle with some fine sandpaper. POINTY SIDE UP

Do not use a flat head screw driver to tighten the jet, I have broke jets this way, use a socket.

Re: gas leak (motobecane)

I took your suggestion and cleaned the entire carb. problem solved!

Re: gas leak (motobecane)

John Joedicke /

Pointy end up on the float.

Re: gas leak (motobecane)

very cool..

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