More PW-50 Help

[CR REV]

I am working on a 94 PW-50. I can't get it to run at much more than an idle. I have replaced the piston, rings, gaskets and that raised the compression from 80 to 105. I have swaped out the carb, coil, cylinder (same bore), head with a running bike (83 model)no luck. I have an 83 that I am using until I get the 94 running. It has 120 lbs compression yet when I put the that cylinder and head on the 94 I lose 15 lbs of compression and that is with a new piston and rings on the 94. What else contribute to loss of compression? The reeds? Seals? Airleak? I am running out of ideas. Oh, I tried disconnecting the harness from the throttle switch, no luck.

Thanks for any ideas!!

 

[smatta4u]

my guess would have been something with the start/run switch if it runs but won't rev. sorry i am of no help.

 

[MX-727]

tcarp had a problem with his PW50. PM him and see if has any insight. He ended up rebuilding just about everything on the bike. As far as the compression difference, I'm not sure if there is other engine differences that could account for the lower compression.

Is the arrow on the top of the piston pointing towards the exhaust port?

 

[CR REV]

Yes, the arrow is pointing to the exhaust port. And I will try to contact tcarp.

Thanks,

Chris

 

[tcarp]

Chris,

your PM mailbox is full.. Check your coils in the generator. I had the exact same problems and replaced all the same stuff but until I replace the generator coils, I got nothing. look at http://216.37.204.202/Yamaha_OEM/YamahaDB.asp?Type=13&A=81&B=11 for a list of the parts involved. Switch the good bikes generator coil plate with the 94 and see what happens. If you want, email me directly at tcarp@dirtrider.net

 

[CR REV]

I'm not sure what's up with my pm it only had one saved messsage but now it's empty. I will check into the generator coils.

Thanks for the info and links.