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PW80/JS80 Runnig to lean?

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We have got a cmg JS 80 (an identical replica of the PW80).

It seems to be very resticted in the exhuast system.

What are the best ways to open it up?

We are worried about it running to lean, what is the best way to tell if the bike is running to lean?

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I'm not familiar with the PW80 clones.

Running lean, with any bike, the easiest usually sure fire way to tell is to pull the plug, if the insulator or electrodes are white or melted, it's running lean. Other signs are revving the motor and then snapping the throttle shut, the engine RPMs will take a long time to come down. It will run very hot. Often, they will seem to have a lot of power which suddenly goes away in a short period of time.

I've heard the mikuni knock-off carbs are a crap shoot to say the least. I'd encourage you to swap in a real VM15, they're plentiful as are all PW80 parts.

In the mean time, clean the carb and make sure the air box is the way it should be with a large foam sheet filter. If the PO removed the exhaust or hacked on the guts, you probably want to replace them with the factory part or build a silencer with packing.

As far as opening the exhaust goes, if it's a true copy of the PW, it came with a fender washer between the exhaust port and head pipe. Take it out.

There's a funnel looking thing in the head pipe, you can either cut/grind it out or replace the pipe with the FMF version. I'm not sure which one is better, but I will say the FMF isn't anywhere near as good as it could be. They are the only ones who make an aftermarket exhaust for the PW.

All your questions have probably been addressed in this thread: http://www.thumpertalk.com/forum/showthread.php?t=738583 which will give you more information in one place than you'd find through out the rest of the 'net combined.

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