Motorcycle Repair: Yamaha PW 50 mid 80s, yamaha pw 50, shaft bearings

Question
Hi Mark,

My name is Heather and I'm looking for some info.  My son is driving us absolutly FREAKIN' bonkers.

DS 7 has a used Yamaha PW 50 mid 80's shaft drive bike. (I really don't know the year.

It runs, the fuel mixture seems to be a little rich, and DH has played with the carb for 3 days now.  The actual problem is the thing has no power.  The wheel barely turns, the engine is running full throttle, but it just does not want to move.  DH had rear tire off to repack bearings and install brakes.  The brake cables are new.  The spark plug is new.  The fuel is new.  Rear and front bearings repacked.  All 3 throttle cables replaced. Throttle, oil pump and choke.  DH seems to think choke may be "sticking".  SO working on carb is starting a ground "zero" for adjustments.




Thats as much info I have.

I also asked Chirs / Falcon who is on the board.

Any help or recommendations would be greatly appreciatied.

Regards
Heather in Canada

Answer
Hi Heather,

After reading your description, things that come to mind are obstructed air intake, seizing drive shaft bearings, and defective transmission. I would check cylinder compression to determine condition of engine and go from there.

This is the kind of problem I would need to physically investigate to accurately diagnose.

There are websites dedicated to the PW50. Some have tech boards and message boards. Maybe someone else has had the same problem. Do a internet search of pw50 and check the various results. Here's a couple of sites that may be usefiul: "www.pw50.com"  "www.bikebandit.com" (click "OEM Parts" and sdelect your MC from the menus).

Keep me posted on what you find. My email is: mshively1@woh.rr.com

Respectfully,
Mark Shively
Dayton, Ohio