A few problems...

Ok, first thing, when I turn on the gas, there is a huge leak that seems to be coming out of the main jet on the bottom of the carb. Not just a drip but a steady stream. Also, when the plug and the exhaust pipe are in, it's harder to start and no lights come on. However, when the pipe and plug are out the engine turns over nicely, sounds good and the lights come on when i pedal. If the lights come on this means I have spark right ? I did the plug on the head test but it was bright out and my friend said he could see a bit of a blue spark. Now I'm assuming this has to do with the compression being released because of the plug hole and the exhaust hole being open, therefore it'd be much easier to turn the engine over because the compression is escaping. Keep in mind I'm not using the decompression, but the new unit came today so I should be able to get that back in order. It's got a new top end including cylinder, piston, rings, gaskets, so I think it's a problem with the carb. Any help is appreciated !!!! Thanx !!!

Re: A few problems...

Try this logic...

If gas is running out of the carb in a steady stream.. then it must be coming into the carb in a steady stream... right?

Well... there is a device in the float bowl who's job it is to shut off the fuel going into the float bowl when the fuel reaches the proper level... it is called the float needle.

The fuel flows in... the float starts to float on the fuel, rising upwards till it pushes on the float needle, which pushes onto its seat, and shuts off the fuel flow.

So... something is stopping your float needle from shutting off the fuel flow.

There is either a piece of crud in the way.. blow it out (and get an inline fuel filter if there isn't one).

Or.. your float needle.. or float.. is 'stuck'... sometimes you can simply pick the rear tire up off the ground and drop it from say... 5 inches.. and it will 'unstick' the float.

Otherwise take the carb apart and check it out and reassemble it.. make sure the float swings up and down alright and the needle slides in and out of its hole alright.

Re: A few problems...

Ron Brown /


Keep in mind that someone (maybe Ree), posted a while ago that he had installed the float upside down. The pointed end goes up.


Re: A few problems...

Alright thanx guys I'll disassemble the carb and have a look and get back to ya !!!

Re: A few problems...

Reeperette /

Oops...yup, that is correct.

With the Encarwi Carb, it's too damn easy to put that float in upsidedown...the pointy end goes UP...or, well. it sticks...resembling your problem here.

I would also clean the damn thing by wiping it down well with some gunk-remover, so it doesn't stick in the correct position either.


Re: A few problems...

Ray Sanders /

If it's a motobecane you are working on it's the carb float.

I'd say judging from some of your problems your exhaust pipe may need a good decorbonizing. Of course it's easy to turn over without a plug in it!!! :-)

Come to think of it since you are mentioning the decmpression, I'm thinking you have a motobecane. Correct me if I'm wrong.

Speaking of which, what make/model is the bike?

If it is a motobecane I'll be more than happy to help, as I've learned quite a lot over the past few months from here, and other sources.

Re: A few problems...

It's a 1975 Mobylette Duamatic, which I've had just about enough of. Ron, I've tried to use your "It's only an engine, it's only an engine..." but I still get so incredibly frustrated wasting the entire day and getting no further. I've even tried "serenity now, serenity now..." but still I get nowhere. I took apart the carb, used carb cleaner and blew out everything in sight. The float seemed a little different then you described Fred, it was about the size of a quarter (I hope Canadian quarters are the same size), about an inch thick and had a needle passing vertically through it with more sticking out on one side than the other. I took the float out, cleaned all around where it sits etc. Still when I turn the gas on, gas comes pouring out of the main jet. I remember a while ago the main jet had this kinda hard stuff on it, which makes me think that someone tried to fix this by just putting something over it, but I don't see how that could've worked. Maybe I'm missing something really obvious, at least I hope so...

Re: A few problems...

Alright... I didn't even know which ped you were talking about in the first place.. so I gave general info.

(some of which is not right for all models)

That is one of those Encarwi carbs?

One important thing that is very easy to miss.

When you are putting that float back in... sit there and get very comfortable with the fact that you have centered that needle in its little hole in the bottom of the float bowl.

If you just drop it in... or even fairly carefully slide it in... the needle can still miss the hole.. because of a bad design IMO of that little boss with the hole in it in the bottom of the bowl.

My advice is to put it in a little crooked on purpose (the needle will miss the hole and slide down the side of the boss).... then slowly pull it back out while applying slight sideways pressure to "feel" it slide up the side of the boss... If you use your eyes and fingers carefully you can make sure it finds the hole... since you cannot see the needle going in... you have to be very careful to correctly locate the hole.

A bad design... (because it is verrrry easy to miss the hole) and only a smart careful person will get it right.

I can't tell you what else might be wrong with it... I am not real familiar with that carb.

I hope that is it.

Re: A few problems...

Hey Fred, it's a Gurtner carb if that helps, I'm gonna try and post a pic of it....Thanx

Re: A few problems...

Ron Brown /


It's only an engine. Then again, carburetors sometimes suck!

The float has a small rod running through it with a point on one end. The pointed end fits into the float needle seat in the float bowl cover. With the cover removed and the gas line attached, you should be able to start and stop the flow of gas by lightly seating the point in the needle seat. If you can't do this, there is something wrong with the seat which should be easy enough to see with a magnifier. If this does control the flow of gas, make sure the float has no gas inside it by shaking it. If it does, replace it, if not, drop the float in the bowl with some gas and make sure it bobs around freely. If not, clean out whatever interferes with it. If it is ok, you don't really have a problem.

It's only an engine, but carburetors sometimes suck : )


Re: A few problems...

lol alright Ron I'll change the phrase to "It's only a carb..." at least until the engine starts giving me trouble and I have to switch back.

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