Motobecans Stalling

A friend and I both have 1976 Motobecane V50s. When we are riding on a hot day BOTH bikes stall at approxomately the same time. Neither will start for at least 1/2 hour. We have checked the plugs and we have a good spark immediatly after the stalls. This means fuel or air. Air seems OK. We tried aviation fuel thinking the alcohol in the new fuel may be boiling. Still stalled. Changed the plugs to platnum, hoping that would help. Still stalled. Has anyone any idea what our problem is? Our only guess at this point is crank shaft seals. Please help a new member... Sid

Re: Motobecans Stalling

Aviation fuel? makes me think there's a lot more to the story..

to test for fuel delivery, make the engine stall.. Then spray some Starter Fluid into the engine. If it restarts, you got some kinda fuel delivery problem. If not, there's something else going on.

Re: Motobecans Stalling

How long were you running the bikes, priorto the stalling?

Last week, I was pulling up a long, steep hill with a passenger on the back of my 50V. It was also pretty warm outside, and high humidity. My bike started stalling out near the top the hill, when it was doing about 15-20mph.

When I got on the flat & level, it started up, and ran fine. It was somewhat low on fuel (but not on reserve), and I'm still not sure what caused it.

Wish I had more info for you, hope you figure it out.


Re: Motobecans Stalling

Make sure the vent holes in your gas caps are clear.

Old condensers in motobecanes fail when hot. I've had this problem on 2 mobies

Re: Motobecans Stalling


I was thinking about the condenser in my bike.. going uphill with 330 pound load must make a lot of extra heat. I'll check it out, if this ever happens again.

Re: Motobecans Stalling

Since they fail so often, I feel like it is a good idea to switch them out after 25 years.

whenever there is a problem, I always suspect the condenser. after putting in a new one, you can just rule that out when the bike starts acting wierd

« Go to Topics — end of thread

Want to post in this forum? We'd love to have you join the discussion, but first:

Login or Create Account