Motobecane expert needed

Hello. My brother has a 78 Motobecane, which is kind of a strange moped, the engine moves as the rpm's increase!! Anyways, does anybody know what the proper size belt for this ped is? He just got it back from a mechanic, and the belt he put on is too small; when you hit 20mph, the clutch starts grinding on the larger pulley just behind it. Also, the belt is so tight you cannot freely roll the bike around, the rear tire just drags. So if anybody knows what size belt we need, it will be greatly appreciated.

Oh yeah, it wont idle either. I tried adjusting the idle screw, but to no avail.

Anybody know where we might locate a manual for this french moped?



Re: Motobecane expert needed

search ;;; old postings

Re: Motobecane expert needed


not sure what brand, but that's the number..

Re: Motobecane expert needed

Thanks for the info!! Found the right size belt, now all we have left to work out is that damn idle...

Re: Motobecane expert needed

Dear Webby /

Use a Gates # 9313 belt. The engine is stalling because the crankshaft seals need to be replaced.

Motobecane service manuals can be purchased from

Re: Motobecane expert needed

To Dear Webby:Many things could cause his moped not to idle yet you state `categorically' that it's the crankcase seals.Don't you know if you're wrong you've put this guy thru a lot of misery for nothing?Let's don't abuse these guys just `cause we want to sell crankcase seals.Even a weak spark plug can cause this problem.I think you owe him an explanation, I.M.H.O.

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