To Troubleshoot A PW80 Motor?

[razorboy]

Hey fellas,
I recently picked up a 1996 Yamaha PW80. The bike appears to have been abused pretty good but I think it can be resurrected with some TLC. Frame and bodywork are good but the motor is cooked by what I can see.
I am a novice at working on bikes but have been doing it for a couple of years now so I am fairly competent.

Here is what I have found so far:
Carb is completely gummed and is currently disassembled and soaking in carb dip - no problem.
The motor is out of the bike and on my bench. it would not kick over meaning that the kick starter comes up solid and will not rotate the engine. Seized piston maybe? Nope, I removed the head and the jug so the piston is just floppin' and still cannot get any crank rotation. I was surprised to find little to no oil inside the crank casing but there was plenty of oil in the clutch casing and everything looked well enough in there. The stator has a lot of rust around it and I can actually get a wee bit of a turn on the crank when I rotate the the stator by hand but it comes up solid in either direction?

So the question is:
What do you think is jammed, seized or whatever? Could the crank itself be seized from lack of lubrication?
I have never worked on a cetrifigal clutch before, but I am assuming that I need to tear it all down to get to the crank innerds....

Any help is appreciated

Bernie

 

[Patman]

Perhaps a bent crank.

 

[razorboy]

I have made some progress on the PW80. I guess lack of lubrication got the innards stuck!
I dumped oil down into the crankcase and after a little wiggling, the crank freed up and now spins like butter. Everything that I could see inside the crankcase looked in decent shape. No rust or corrosion but I am fearful that maybe bearings or other spinning assemblies could have pitting or corrosion that will shorten their lifespan. Oh well, it is just a little pitbike so I am not going to lose any sleep over it.
New Question:
I am going to have the jug cleaned up and feeling the scoring on the walls and some pitting at the top, I am assuming that I will need to go to at least the next oversize piston. So my question is who makes this determination and how do you know how much material can be removed? Do I check with Wiesco first to see what they have for oversized pistons?

TIA
Bernie

 

[2smoke4life]

pw80 help

i got a 1996 pw80 pink and i think the rings are shot but i need help in getting the jug off! can someone help me

 

[j.lawson]

I have made some progress on the PW80. I guess lack of lubrication got the innards stuck!
I dumped oil down into the crankcase and after a little wiggling, the crank freed up and now spins like butter. Everything that I could see inside the crankcase looked in decent shape. No rust or corrosion but I am fearful that maybe bearings or other spinning assemblies could have pitting or corrosion that will shorten their lifespan. Oh well, it is just a little pitbike so I am not going to lose any sleep over it.
New Question:
I am going to have the jug cleaned up and feeling the scoring on the walls and some pitting at the top, I am assuming that I will need to go to at least the next oversize piston. So my question is who makes this determination and how do you know how much material can be removed? Do I check with Wiesco first to see what they have for oversized pistons?

TIA
Bernie

Let the machine shop or wherever you send it help you there. If it's somthing minor it may be able to be honed out, if not you'l have to bore. I dont know if these are nickasel plated but if they are you'l have to have it re-sleeved. And yes, I'd
check what sizes wiseco has for your model bike. Good luck. :cool:

 

[FruDaddy]

I dont know if these are nickasel plated but if they are you'l have to have it re-sleeved.

I don't either, but if it is Nikasil, then there isn't going to be a sleeve, the solution is re-plating.

Razorboy, a Clymer manual for the PW80 would be a really good investment for you. Almost as good as a factory service manual. Don't fret about the years, I don't think that they have changed anything about the PW80 since it's inception.

 

[j.lawson]

I don't either, but if it is Nikasil, then there isn't going to be a sleeve, the solution is re-plating.

Razorboy, a Clymer manual for the PW80 would be a really good investment for you. Almost as good as a factory service manual. Don't fret about the years, I don't think that they have changed anything about the PW80 since it's inception.

Yeah, your right, dont know what I was thinking.
But you can have them bored and sleeved for over-sized pistons if you wanted.

 

[FruDaddy]

OK, the plating info is useless here anyway. I just checked and the PW80 is iron-lined. According to the Clymer manual, it can be bored to fit 2 oversized pistons that are offered by Yamaha (the sizes are not specified). Also, for a reference, the service limit for the bore is 47.10mm (new is 47.00-47.02mm).