I was ridding my PK80 up a steep hill and the engine just stopped. i let it cool off a little and tried starting it. there was little resistance to me pedaling to start it(there should be since i have a shift kit). When i finally walked it home and took it apart i discovered the upper piston ring had broken in half and tore a chunk out of the piston and the cylinder. The other half of the piston ring is somewhere in my muffler. I can hear it jingle when I shake it. I wanted to just buy a new top end assembly but i can't find one. I almost bought a skyhawk top end by accidently. I didn't know there was a difference. Does anyone know how to either fix this cheaply or find PK80 parts? If i wasn't planning on going to college in a few months I would just buy a new engine but thats a little too pricey right now.
Engine EXPLODED... can it be saved?
- Thread starter justthisguy1292
- Start date
Justthis,
I'd try several of our sponsors. I know PistonBikes has them.> Motorized Bicycles Gas Bike Engines Gas Powered Bikes Motorized Bicycle Parts You should be able to find the necessary parts to fix that little guy cheaper than a complete engine.
Tom
I'd try several of our sponsors. I know PistonBikes has them.> Motorized Bicycles Gas Bike Engines Gas Powered Bikes Motorized Bicycle Parts You should be able to find the necessary parts to fix that little guy cheaper than a complete engine.
Tom
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Getting the whole assembly doesn't make much sense, a new piston/ring set and a cylinder should be all you need, these are the cheapest i can find:
Bike Motor Engine Piston Set 80cc/66cc Parts - Motorized Bike Piston Set 80cc/66cc Parts - Bike Motor Piston Set 80cc/66cc Parts - Motorized Bike Parts
Bike Motor Cylinder Body - 49cc Parts - Motorized Bike Cylinder Body - 49cc Parts - Bike Motor Cylinder Body - 49cc Parts - Motorized Bike Parts
as long as your writs pins ok this should be all you need, you can make a base gasket pretty easily but if you want to buy that too....
Bike Motor Parts Cylinder Base Gasket 80cc/66cc - Motorized Bike Cylinder Base Gasket 80cc/66cc Part - Motorized Bike Parts
So that's all you'd need for 36 bucks, 14 bucks cheaper than top end assembly at spookytooth.
If you think there's damage to the writs pin and/or the head you can just buy the whole top end for 50 bucks:
55cc & 60cc Complete Upper Engine Assembly
That should do it, good luck on the rebuild, and be sure to keep any parts that still look ok...
Bike Motor Engine Piston Set 80cc/66cc Parts - Motorized Bike Piston Set 80cc/66cc Parts - Bike Motor Piston Set 80cc/66cc Parts - Motorized Bike Parts
Bike Motor Cylinder Body - 49cc Parts - Motorized Bike Cylinder Body - 49cc Parts - Bike Motor Cylinder Body - 49cc Parts - Motorized Bike Parts
as long as your writs pins ok this should be all you need, you can make a base gasket pretty easily but if you want to buy that too....
Bike Motor Parts Cylinder Base Gasket 80cc/66cc - Motorized Bike Cylinder Base Gasket 80cc/66cc Part - Motorized Bike Parts
So that's all you'd need for 36 bucks, 14 bucks cheaper than top end assembly at spookytooth.
If you think there's damage to the writs pin and/or the head you can just buy the whole top end for 50 bucks:
55cc & 60cc Complete Upper Engine Assembly
That should do it, good luck on the rebuild, and be sure to keep any parts that still look ok...
I would call Justin at Pirate Cycles.
His site dosen't show the parts available but he has them all.
Thats where i got my PK80.
I broke the rings trying to put the jug back on.
He's sending me a new set.
Shipment is fast and service is good.
Call him he will take care of you.
His site dosen't show the parts available but he has them all.
Thats where i got my PK80.
I broke the rings trying to put the jug back on.
He's sending me a new set.
Shipment is fast and service is good.
Call him he will take care of you.
My guesses would be.
#1 ring flutter caused by high rpm.
#2 locating pin came loose from piston.
#3 excessive heat caused rings to bulge out into the ports and get caught on a sharp edge or Casting flash.
#4 Bore Distortion caused by excessive heat.
Other than that the rings are close to the top of the piston.
only a little over .100 inch.
Typically .200 inch is reccomended allthough closes to the top is the best except it exposes the ring to more heat.
#1 ring flutter caused by high rpm.
#2 locating pin came loose from piston.
#3 excessive heat caused rings to bulge out into the ports and get caught on a sharp edge or Casting flash.
#4 Bore Distortion caused by excessive heat.
Other than that the rings are close to the top of the piston.
only a little over .100 inch.
Typically .200 inch is reccomended allthough closes to the top is the best except it exposes the ring to more heat.
Yep it shouldn't happen.
But like i said the top ring close to the piston crown.
We know alot of these engines come with casting Flash in the ports.
All it takes is a little junk in the wrong place at the wrong time.
I just orderd 2 sets of rings for my PK.
The brand new one.
I broke a ring trying to put the Jug back on.
So they are fairly brittle.
2DOOR
How many miles were on the motor?
But like i said the top ring close to the piston crown.
We know alot of these engines come with casting Flash in the ports.
All it takes is a little junk in the wrong place at the wrong time.
I just orderd 2 sets of rings for my PK.
The brand new one.
I broke a ring trying to put the Jug back on.
So they are fairly brittle.
2DOOR
How many miles were on the motor?
I was getting close to 1000 miles. i think I can find the parts. Not entirely sure how it all goes together. I'm betting there are some posts on how to do that. I just took another look in the cylinder and theres a second gouge. it looked like just a smear but when i felt it it was definitely a gouge. Its maybe an 1/8 inch wide and almost runs the entire height of the cylinder. probably happened when the half of the piston ring was banging around in there.
