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Discussion Starter #1
I Have a 1995 XLT special that I am working on for a friend, It had low compression in the #1 cylinder. After I took the head off, I found major damage to the head, piston surface. When I took the cylinder off I found that most of one side of the piston was gone; It looked like the material around the circlip came off. I split the crankcase and found no damage to crank. Everyone I have talked to has told me to get a rebuilt crank, just wondering if anyone has any thoughts to if I really need a new(rebuilt) crank.What type of things should I inspect above and beyond what the shop manual tells me. Thanks
 

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Welcome to the site! How many miles on the sled and how much money does he plan to spend? Also what was the reason for the piston failure? Generally the only problem with the cranks are the pto bearings which are fairly easy and cheap to replace. Pull up and down on the connecting rod to determine if the lower rod bearing is worn. Any play and I would replace it. Don't confuse lateral play with perpendicular play. This requires a good crank shop and is more expensive. As far as the head, just smooth the burrs out and buff it up a little. Hope this is of some help.
 

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The sled has 2100 miles on it. I have not figured out why the piston failed yet, But I'm going to show a polaris mechanic today and see if they have any ideas. There is no lateral play, but how much can it move perpendicularly. all the bearings move smoothly.
 

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If all the bearings spin smoothly, with no excessive noise, they're PROBABLY ok.......I mean, I haven't seen, or heard them myself.

Just be sure to clean the crank and bearings really well to be sure there is no metal debris from the melted piston in them. Then make sure to apply 2 stroke oil to the entire thing, crank and bearings.

I'm not sure what the spec freeplay on the rod "big end" bearing is. Just ask your Polaris mechanic, he should be able to tell you.
 

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I would at least have a reputable place check the crank out at least. Most places do it cheap and it might be good insurance. Most will have seen enough of the Polaris 600 trip. cranks to tell ya if the bearings are good or not.

If the motor was siezed, more than likely the crank runout is bad. Also, I know Polaris updated the cranks after 96, so you might want to see if you can upgrade them to the oil fed bearings.
 
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