My Motobecane is running rough, HELP

Bruce Matthews /

Well I guess I'll have to turn in my big bikes and become part of the army now. I just got my 1970 50V running a little while ago for the first time. This is after it had sat in storage for over 20 years.

I have a couple of questions about setting up the carb. At full or part throttle it runs just fine, at least I think that anemic pull is running fine, but at idle it runs down and dies. If I jazz the throttle a little it can pick up but it seems lean. I checked the float level after the runs and the gas level is about 1/4 to 5/16 below the brass jet in the slide area. Does this seem about right? I don't see any idle mixture adjustments on the carb so I'm at a loss about setting the mixture except for changing the main jet or the float level.

Bruce Matthews

Re: My Motobecane is running rough, HELP

Ron Brown /


You will get a better response if you post this in the correct forum.

Anyway, the carb has idle passages even though it does not have a removable jet or mixture screw. Disassemble the carb and clean it thorougly then try it again.


Re: My Motobecane is running rough, HELP

It's probably what Ron said,but do a compression check if it isn't.Since it was sitting that long,the rings could be partially stuck,and this cuts suction thru the idle passages.Always hold the throttle open when you check compression. Hope you solve it! BYE!

Re: My Motobecane is running rough, HELP

if you need new rings go to you could even get a brand new piston there!!

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