PW 80 2002 runs badly

[LwP]

Where is the oil sump drain plug? Is the oil level read with the dipstick screwed in or loose? It might be overfull, would this cause black exhaust or unable to idle?
Also, it won't start except with starter fluid with difficulty (drill motor on shaft nut) and gives a very high RPM which cannot be fixed by air and fuel screw adjustments. Carb cleaned, float adjusted, all jets poked and cleaned, cable slack, throttle slide is correct in place, float valve normal, fuel bowl level is correct.
The choke lever seems to have no return spring, it will stay in or out regardless and has no effect on idle or starting. The choke plunger at top of carb is cleaned and not stuck, the cable has minimal friction.

 

[LwP]

Add to first post: New BPR6HS spark plug, clean tip even with black exhaust. And compression is 100.

 

[LwP]

Add to first and second post: It started yesterday using the drill motor and fluid and I let it run for several minutes using gas. It ran at high speed only, choke and grip twist and screw adjustments would not slow it down. Screw adjustments did stall the motor, and the screws were way out of standard turns. While it ran yesterday, it produced heavy black smoke and spewed thick black oil out the pipe. Why? The oil reservoir is half full, gas half full, and draining a little gas from the float bowl I see the color and odor of 2-stroke oil mix although the mix seems to be kinda thick.
Today with the screws both at 1.5 turns, it would not start, even with fluid. It will not pop while cranking, but pops a little on starting fluid.

 

[RM_guy]

I'm not very familiar with the PW but it sounds like you have a leaky main seal and it is sucking trany oil (and maybe some air) into the combustion chamber. You can do a leak down test to see in the seals are leaking.

 

[LwP]

Thank you, very helpful. I pulled the flywheel, ignition plate, and oil seal. It was destroyed. Can't find one in stock in Denver.

Is this likely the only thing wrong with this bad boy? I guess I'll find out.

 

[RM_guy]

It very well may be the only problem. I chased a "jetting" issue on a bike for a month before it dawned on me that the seal might be bad. Fixed it and it ran like a champ! Good luck!