Motobecane gas out of exhast

This is for my Motobecane Mobylette 50.

So, I did get it running yesterday for a bit but today I noticed gas has run out of the exhaust port down the muffler? The Carb is brand new, a dellorto.

One odd thing was when I was cleaning up the moped, it looked like there was baked on caulking all around the exhaust port? I did add a new copper o-ring and copper paste on the threads.

What's everyones thought at this? In the pic you can still see traces of the caulking.

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Re: Motobecane gas out of exhast

more pics of what I think part of the problem is.

This isn't factory right?

But even if it sealed it shouldn't be leaking gas there right?

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Re: Motobecane gas out of exhast

Yeah its not stock. Somebody welded or brazed some goop on there. So normally on the exhaust theres a thick washer that presses the copper oring on a machined surface in the exhaust port when u tighten the nut down.

Re: Motobecane gas out of exhast

> pat splat wrote:

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

> Yeah its not stock. Somebody welded or brazed some goop on there. So

> normally on the exhaust theres a thick washer that presses the copper

> oring on a machined surface in the exhaust port when u tighten the nut

> down.

Thanks I’m thinking my only option is to replace the top end and exhaust.

Re: Motobecane gas out of exhast

Well depends on how crafty you are.

Re: Motobecane gas out of exhast

Two-stroke motors will always lose some unburned mixture out of the exhaust port because the exhaust port is still open as the intake/power stroke begins. Some of it sometimes gets past the pipe to head joint, but it usually ends up in the muffler where it burns up.

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