Motorcycle Repair: Set timing to pw80 yamaha, jet nozzle, bill silver

Question
Hi Bill,
My son's 2003 pw80 yamaha starts and idles but bogs out when accelerating.  Maint manual suggest setting timing.  I hooked up a timing light but need to know how to hook up tachometer to check timing at 4000 rpm per manual (say should be 20.6 deg at 4000 rpm).
If it is off, how do I adjust.  The marks line up at idle, but grow apart as I accelerate motor.

Answer
Jerry, the microfiche at http://www.bikebandit.com/houseofmotorcycles/2003-yamaha-motorcycle-pw80r/o/m744... wasn't too helpful, however it appears that the bike has a CDI type of ignition that is non-adjustable. Generally the systems are pass-fail. If you see the marks moving as you rev it up, then it is probably doing its job, just fine. The CDI box has the advance curve built in from the factory. At $180, it isn't something that you want to replace without doing full troubleshooting.

I am not a Yamaha guy, but have seen a PW50 in the past and was aware that they had some kind of switching to soften the power band for small kids, just learning to ride.

If the bike hasn't been ridden for awhile, remove the carburetor and clean out the float bowl and main jet. Check the needle for any globs of old fuel deposits and the clogged holes in the main jet nozzle. Today's fuels do not store well. They evaporate quickly and leave un-burnable liquids in their places. Replace all fuel with fresh stuff. The parts list shows 3 different options for main jets, so check to see what yours is now and perhaps you may have to swap it to another size.

Put a fresh spark plug in it, make sure that the spark plug cap has 5k ohms or less resistance and it should be good to go again.

Bill Silver