Carb problem. Need a fix. By scooteraddict (Read 653 times)

[scooteraddict]

Now that I have my bike (a MC 250B) running like a top, I have a small problem with the Carb. It seem that after starting the bike cold and taking it for a ride at high speed, WOT, the Carb likes to sticks. Can't tell if the needle is coming out of the seat or the slide just gets hung up. Since I had just recently tuned the Carb which I can achieve speeds of 80mph (chinometer reading). What I,m thinking is that the vacuum at that speed is so great that its raising the slide too high.

Any ideas to combat this problem?

[Alleyoop]

Did you happen to take the carb apart. Maybe you put the Needle Guide in wrong and it is not sticking up high enough.
The other problem could be that the Cable is sticking or the Butterfly is sticking. It may not be the Carb at all just the Cable. Have you tried cleaning the cable and putting on some Litinium grease on the cable.
But anyway the Needle Guide should stick up like this:
Alleyoop

[scooteraddict]

No problem with the butterfly or cable. IT IS the slide.

When I experience the symtom after slowing down and giving it gas from a closed throttle, I experience a slight lag, then it picks up.

When I notice this I pull over and remove the Carb top to the diaphragm and it is stuck up in an up position. A slight touch will knock it down again.

As far as the main jet (a 118) being to big, the next lower one would cause the bike to run lean.

[ce]

Sounds like the needle spring is out of position, remove the needle from the diaphragm and examine. Also check the vac line to the air cutoff valve.