Motobecane still not running right

i have cleaned the pipe, taken off the cylinder and checked it, and taken the carb apart at least 4 times. It all looks very clean and in good condition. my problem is that sometimes the bike dosent seem to be reving as high as it should Normally, i can get it up to like 30 mph on flat fround, and it revs like crazy. But the other half of the time, it doesnt rev quite as high, and only runs like 20-25 mph. when it runs bad, it will rev, and then the revs drop a little, then it will pick up a little, and then drop off again. This cant have anything to do with the timind, points, or any part of the ignition, could it? what else could it be????

Re: Motobecane still not running right

go through fred's guide step by step. check your spark plug. clean your carburetor thoroughly again if necessary and get into every corner of it. check your petcock and your idle screw. then start looking at timing and all that.

fred's guide has all that in it. go w/ that.

Re: Motobecane still not running right

Chris Robertson /

When you say the revs drop and pick up again, do you mean that it feels like you're losing power at high speed, and then you get it back again once you slow down a bit? Does the engine begin to four-cycle (drops in pitch)?

I had this problem with one of my mopeds before. The problem is either airflow or carburation.

Is your air filter clean? Note that contrary to what common sense would tell you, some mopeds run like CRAP whenever the air filter is removed completely --they need a bit of resistance.

Is your fuel filter in good shape? You can spend a half hour cleaning your carburetor, and have it get plugged up again almost instantly with dirt or rust if you don't have a working filter.

Here's what to check in the carb:

o That the main jet is absolutely clean. Take it out and clean it thoroughly.

o Is your float still good? If you shake the float can you hear gas inside it? If so, you'll need a new one.

o Let your carburetor soak overnight in a bowl of Wynn's carb cleaner (outside that stuff reeks). REMOVE ALL PLASTIC AND RUBBER PARTS from the carb first! Trust me on this one --rubber will expand and not shrink back to size for weeks.

Good luck.

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