Strange Problem

Christopher Paquette /

Ok heres the deal. I took my moped out of storage and it ran fine for a few weeks, so i put it in my truck and took it up to my camp. Now it dogs down when you give it gas and has very little throttle response. Moreover, when i press on the choke it has all the power in the world. Let go of the choke though and its back to being a powerless turd. I've disassembled the carb and cleaned it, that didn't help. Inside the carb the choke seems to be moving up and down fine. Im stumped, can anyone help me?

Strange Problem

Christopher Paquette /

Let me explain a bit more, my moped is a 79' motobecane mobylette. It has a gurtner carb and a v50 engine. It's an incredibly french bike.

Re: Strange Problem

sure sounds like you have fuel delivery problems.. Rust and stuff collects on bikes in storage. Some of it breaks free and clogs up a filter or something. Since your bike runs better choked, it indicates a lack of fuel. Perhaps the float is low but i suspect fuel starvation from a clogged-something.

the carb is only a small part of the fuel flow circuit. Clean the rest of it.. all the way up to the gas cap... filters, screens, everything.

Re: Strange Problem

Christopher Paquette /

The fuel shut off valve was stuck partially close. that was part of the problem. Alas the problem persists. I cleaned the gas tank filter as well as the actual shut off valve. It needed it... the gas tank is pretty rusted...When i cleaned the carb I just sprayed the jets with carb cleaner, do you recommend using air instead?

Re: Strange Problem

i recommend going to the extreme when cleaning carbs.. Anything you do to save time or effort or expense when cleaning a carb will probably result in a waste of time and effort and expense..

Spraying carb cleaner might loosen some crap and push it deeper into the passage.. Compressed air is no guarantee but it's the best, short of a pressure washer.. a cheaper version of which you can buy for a few dollars in the autoparts or tool store. It's an air-blow gun that has a hose for siphoning solvent.. i think they art called Engine Cleaning Guns or similar. Blast the passages with solvent at 110 psi..

Get it clean whatever it takes.

The rest of the system is just as important as the carburetor. Hidden screens.. internally corroded rubber fuel lines .. look closely and examine the entire fuel pathway.

Re: Strange Problem

Christopher Paquette /

I've cleaned everything as good as i possibly can. It's a bit better now, but it won't idle and there is alot of oil coming out of the muffler. Im going to go get a new spark plug. After that im sort of stumped on this thing. When i hold the gas wide open it revs up and down. Only when i pump the choke does it reach full potential.

Re: Strange Problem

hmm.. maybe you have vacuum leaks. This will inhibit a smooth idle as well as cause an inconsistant fue/air mixture and erratic engine speed.

Spray some Starter Fluid around the intake manifold (between the carb and engine) and see if RPM changes.. if so, there's a leak. Disassemble and coat the surfaces with Permatex 2 (non-hardening gasket sealant)

as far as oil out the exhaust, it may be just the collected rich mixture that you have been pumping into the engine lately..

Get the bike running well and take a ride for a few miles before making a judgement about oil out the exhaust.

Re: Strange Problem

Christopher Paquette /

thanks for you help ill try that

Re: Strange Problem

Christopher Paquette /

Thanks man you were exactly right! Problem solved in less than a day. I really appreciate your help. Im a software engineer in college if you ever need any computer help email me at csawurm@yahoo.com Thanks Joe.

Re: Strange Problem

software, eh.. That could be handy.. a couple years from now when you have your own multi billion dollar company, i might give you a call and remind you that you owe me one :)

Re: Strange Problem

Christopher Paquette /

Maybe you confirm something for me...when i try to spin the front wheel freely it spins kinda hard. When I run the machine for a long time and come back and try to spin the wheel again, it's nearly impossible to spin...I was told the cause of this is bad wheel bearings, what does the master moped mechanic say?

Re: Strange Problem

heh.. master of none..

front wheels .. you have brake pads and bearings.. Both are easy to check. If i had to guess i'd suspect a problem with the brake actuator inside or the lever outside the wheel or the cable adjustment.

Bearings that as so bad they wont allow the wheel to turn will have other symptoms as well.. like the wheel makes lots of noise, wobbles on it's axel, and gets hot as hell.

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