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PW50 Idling High

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These kids dirt bikes are going to be the end of me.

Got a PW50 that starts fine and when switched to run it goes to high idle.  I've read it could be everything from clogged exhaust to some kind of air leak.  What I don't understand is "where" to look for an air leak.

The exhaust pipe and muffler had a ton of carbon and oil in it.  I'll probably just replace that but something tells me it's not going to be that easy.  The person I purchased this from put a new carb on it hoping that would fix the problem but no no bueno.  You can adjust the air screw and idle screw all the way in both directions and not get a ton of change.

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Could the throttle cable be adjusted too tight holding the slide open a little.



This could be vary true, These little bikes take a lot of crashes to the cable off the throttle assembly. It might be messed up or broken.

That cable later splits into 2 and one goes to the oil pump. Might be a little messed up at the yoke ect. The spring assembly at the oil pump commonly gets clogged with crap and needs to get cleaned if the throttle gets sticky.


Some times if somebody has removed the carb, the slide get installed 180 degrees backwards. It fits back in but gets held wide open because it isn't in the right way. Check that the small tapered ramp notch in the slide is the side towards the air screw.


As for the air leak. You would be looking at the connections between the carb and the cylinder. A leak after the carb mixes it's air/fuel mixture leans out the engine causing a high idle. To check this you can use a can of carb cleaner and spray a little at the connections between the carb and cylinder and see if the rpm increase even more. But be careful on these little bikes, the air intake is so close it is easy to get a false increase when the carb cleaner enters through the normal air intake.

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On 9/11/2017 at 3:59 PM, reeltight said:

These kids dirt bikes are going to be the end of me.

Got a PW50 that starts fine and when switched to run it goes to high idle.  I've read it could be everything from clogged exhaust to some kind of air leak.  What I don't understand is "where" to look for an air leak.

The exhaust pipe and muffler had a ton of carbon and oil in it.  I'll probably just replace that but something tells me it's not going to be that easy.  The person I purchased this from put a new carb on it hoping that would fix the problem but no no bueno.  You can adjust the air screw and idle screw all the way in both directions and not get a ton of change.

I have not had an opportunity to work on the PW50 personally, but I think the fact that you can turn the air screw and idle speed screw all the way in both directions without appreciable change is key. This seems to suggest that something is holding the throttle partially open. As others have suggested, perhaps a bad or missadjusted cable. Look into the carb. If it's like most you should be able to see the slide closing slightly as you turn the idle speed screw counterclockwise. Throttle cables often have adjustment by means of threaded ends. The cable should be loose when the throttle is released. There should be visible free play of about 1/4 inch.

 

 

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I really appreciate it fellas...I'll start working on it again this weekend and report back.  I actually have a new throttle cable so I might as well put that on and see what happens. 

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