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  #1  
Old 07-26-2018, 08:18 AM
cowboyona426's Avatar
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Default Yamaha PW50 help needed

     

I'm trying to get my son's PW50 ready for a local race event this weekend and it's giving me a ton of grief. It quit running on him last week, and since the top end had been making a terrific amount of noise I went ahead and installed a new (aftermarket) top end kit but the bike still wouldn't run. After much frustration and digging around I pulled the reed cage out and found a small pebble in one side of the reeds that was holding it open (pebble got in due to a failed airboot). Got that resolved and now the bike will fire up and run, but it's loading up at higher RPM. With any sort of airbox installed (with or without the filter) it will barely rev up at all and won't idle. I have the OEM airbox which is basically useless due to the aged and stiff airboot, and an aftermarket one with a new filter in it but neither one makes any difference. I can run it with an open carb in my shop and it runs ok, I have read that these little motors like a load on them and I suspect if I actually turned him loose it may clean up and run just fine but I don't want to risk a new top end running with no air filter.
Any tips/suggestions from the crowd? Carburetor is clean as a whistle, jetting is stock, stock size piston/cylinder, new plug, fresh fuel, new coil, good used OEM reed assembly installed due to the original being bent from the pebble, spark arrestor cleaned up.
I need to make sure the needle is in the carb slide correctly (one of the few items I haven't checked yet). The exhaust is also slightly misaligned to the outlet on the cylinder and slightly beat up from years of abuse, but it's not enough I could imagine it causing the bike to run this poorly.
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Old 07-28-2018, 11:44 PM
gusco's Avatar
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Right side crankseal, maybe??
Or maybe the oil pump somehow was affected and needs adjustment (I've heard adjusting it can be quite a pain...)
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Old 07-30-2018, 08:45 AM
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Ended up being a small pebble in the reed valve holding one side open, due to a failed airboot. Got it sorted just in the nick of time after a few other little things popped up.
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Old 08-03-2018, 08:46 PM
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Great to hear! Glad you got it back up and running well
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Old 08-04-2018, 06:29 AM
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Good job! I was thinking maybe a cracked reed.
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