[reed]

I have a broken 96 580 ext powder special. One of the pistons blew. I am a good mechanic but have never worked on snowmobiles. The bolts, water pump, oil pump, and everything is taken off the case except the stator and the wheel. Is this wheel the clutch? Do I need to take it or the stator off to pull the cases apart? I have new pistons and a new used cylinder. I'm pulling the cases apart to clean and inspect. Is their anything else I should do? Thanks alot

 

[ZR Rider]

Ummm, why are you splitting the engine if you have a bad piston?? Take the jug off... in the sled, change the piston, new base gasket, slip the jug on, tighten fill and go!!
Broke ring, hole in the top or piston skirt??? Which one?
Is the jug really bad??

 

[reed]

Ummm, why are you splitting the engine if you have a bad piston?? Take the jug off... in the sled, change the piston, new base gasket, slip the jug on, tighten fill and go!!
Broke ring, hole in the top or piston skirt??? Which one?
Is the jug really bad??[/b]

The cylinder was definitely ruined, badly scuffed. A large section of the piston is missing though No metal shavings, no chunks of metal. I am assuming they are in the case

 

[94ZR580]

Can you rotate the crank? I usually find most of the debris goes out the exhaust port. If you do want to split the case you need to remove the flywheel and stator because the stator plate screws into each half of the case. Place alignment marks on the stator and plate before removing to get your timing back when you reassemble. The primary clutch needs to come off too, so you can remove the plate on the PTO end of the case.

 

[reed]

I think you just talked me out of splitting the case. Thanks for your help. I wish I would have never pulled the motor. But oh well, at least I understand it better. Is it normal for this machine to fry piston and cylinder at only 3000 miles? I just hate to put back together and see it go again soon.
Thanks for your help.

 

[94ZR580]

It is much easier on your back if you can work on it on a bench instead of the belly of the sled. I don't know if I would it is normal, but it is not unheard of for pistons to fail with 3,000 miles on them. You have to know why the engine went down to make any comment on what happened, but I would most definitely replace both pistons to give a completely fresh top end. Make sure you get a fresh crosshatch on the cylinder walls to go along with the new rings. If the problem was from a lean conditon make sure you address any potential air leaks. The rubber can crack under the clamps on the carb flanges and let air in.