Motobecane Over Heating

Hayden Stevens /

Jun 07, 2005 10:29AM

I'm trying to get a motobecane running so I can sell it to my friend, I got the engine running fine, but after about 10 minutes it will die if I slow down and won't start again until it cools off....I don't think oil is the problem because I put the engine on My moped with the Gas that I use in my engine (Mine doesn't over heat)...So what else could be the problem?....the engine is cleanon the inside, there are no boken cooling fins, it's clean on the outside....Any suggestions would be great....

Re: Motobecane Over Heating

Dan Adams (50:1) /

Go to branch

danadams

Jun 07, 2005 07:44PM

gas cap vent hole clogged, or faulty condensor are my 2 guesses.

search for lots of threads on both subjects

Re: Motobecane Over Heating

Joe Woods /

joew

Jun 07, 2005 08:08PM

maybe someone tried to modify the cylinder or head.. people are always talking about shaving this and trimming that..

Re: Motobecane Over Heating

Hayden Stevens /

futaba OP

Jun 07, 2005 09:46PM

naw, I rebuilt it myself...and other pistons from the same type of engine fit the cylinder just the same as the original...it's not modified....my friends dad says either not enough oil (not the problem) or soo much friction somewhere....I don't know....anymore ideas?

Re: Motobecane Over Heating

Joe Woods /

joew

Jun 07, 2005 09:52PM

if you rebuilt it, you should have a clue as to what it might be..

did you gap the rings? Was break-in sucessful? Did you bore the cylinder to fit the (new?) piston with proper clearances?

there's a zillion things it could be but without all the info its just wild guesses.

_after about 10 minutes it will die if I slow down and won’t start again until it cools off_

Hard to start (carb or ignition troubles?) or actually overheated and piston partially seized, stuck in the bore?

Re: Motobecane Over Heating

Hayden Stevens /

futaba OP

Jun 07, 2005 11:06PM

after it shuts itself down, it will still turn over, but it won't fire at all until it cools down.....I didn't bore anything and I didn't add any new parts, I just thoroughly cleaned the cylinder and the piston and the rings with 600 and/or 800 sandpaper and cleaning spray.......the sand paper did not scratch the bore or piston if thats what your thinking.........but....gapping the rings.....please go on

Re: Motobecane Over Heating

Dan Adams (50:1) /

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danadams

Jun 07, 2005 11:09PM

I do not think it is overheating. bad condensors on mobies stop working when they get hot. are you sure your fuel flow is good? checked that gas cap yet? blow through the hole.

Re: Motobecane Over Heating

Hayden Stevens /

futaba OP

Jun 07, 2005 11:15PM

the gas cap is fine, It is deffinately something on the engine because I put over 800 miles on that bike with a different engine.....I'm trying to test an engine for a different bike on my bike because my bike is registered

Re: Motobecane Over Heating

Joe Woods /

joew

Jun 07, 2005 11:25PM

Brand new rings are first slipped in, level and close to the very top of the cylinder and the end-gap is measured.

Since rings expand there must be some gap, but not too much. Corrections are made a little at a time.. carefully.. with a sharp file.

I'd check out that condenser possibility.. swap the condenser with a known good one. I dont own a moby and would tend to listen to people who do.

may as well pretend you want to give the bike a complete tune-up and go through everything else too.. FREDs guide

MOPED ARMY

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