unstable idle rpm and almost no power

[Norlig]

On the Scooter (Speedfight 2 50cc LC) that I recently fixed, The RPM is behaving weird.

When I start it and try to drive, it has almost no power whatsoever, but if I let it idle for a while so it gets hot, about 1m30s, I can try again and it will give Okay power for a 50cc. but it Idles really high and last time I sat on it, it idled so high that it gave forward momentum for a bit even.

The Cylinder and piston is new as the ones it had was "melted", could this just be the Run in causing this? Any other scooters Ive ridden could drive immediately when started.

Also tried turning the Idle screw on the carb, when it was Idling high/hot, the RPM did not change.

[Vincent]

You could check that the throttle cable isn't getting snagged anywhere and make sure there is a small amount of slack on it. It may also be an air leak between the carb and the air filter or the carb and cylinder.
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[Norlig]

I did not find any places that the throttle cable was "snagging", it goes nice back and forth on the motion, not feeling it catch and hold anywhere.

Also sprayed some multi spray (which said it could be used for starting spray on engines) around the air filter box, cant say that the RPM changed much at all, unless I blew it in the intake tube of the air filter.


There were 2 screws on the carb, I guess one is the Air/Fuel mixture screw?

I tried changing these two around and I did hear the RPM change a little, but not much. also tried the throttle

https://img546.imageshack.us/img546/5696/2rzj.png


A coworker at work said he had been messing with carbs on his own bike and that what I described to him sounded like the engine didnt get enough air (bad air/fuel mixture), but however much I screwed them in either direction, the engine still died refused to power up when turning the handle.


When I cleaned the Carburettor, I screwed the Jets in all the way, and tightened them. A friend of mine said you should screw them in all the way and then out a bit, could this be the error I have? I had the same error before I cleaned it because of was overflowing.

[andym]

It sounds like you have just mucked up the mixture and idle (either that or the throttle slider is sticking slightly inside the carb).

I can't remember off the top of my head, but a good place to start would be both the idle and mixture screws turned in as far as they will go (without forcing them) then bring both of them out about 2 turns and try to adjust from there, as long as the back wheel is off the ground have the idle set higher that way you will hear a definite difference when adjusting the mixture... and it'll be less likely to cut out. When you get the mixture right adjust the idle back down again.

As for the jets, they only need tightened slightly more than hand tight, you have checked to make sure they are completely clear haven't you?

[Norlig]