Motorcycle Repair: yamaha 50 shaft drive, yamaha pw 50, shaft drive

Question
Hi ummm.  Chris / Falcon,

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.

Any help or recommendations would be greatly appreciatied.

Regards
Heather in Canada

Answer
Hi Heather.
 At full throttle, the wheel should be spinning like mad.  Did anyone think to check the clutchplates and springs?  Chances are that they are the original and in deperate need of replacement.

As far as the bike running rich, start with the easy stuff like air filter (is it clean?), then do a complete and total cleaning of the carb.  If all else fails, then go to the mixture screw and turn it in a little at a time (1/8 - 1/4 turn).  Clean the plug before each adjustment and pull it out to check after each test run.  It should come out, at most, a little brownish, but not dark or blackened (running too rich), nor should it come out whitened or burned off (running too lean).

Start with that and see what you find.
 BTW, I hope your son is helping with the work if it's his ride.

Good luck.
FALCON