Scored Piston?

[HammsRMK]

Hey guys and gals just wondering if anyone could help me out with this one. My bro blew his sled up later year in SD, because of over heating issues. We sent the motor off and got the crank redone, jugs coated and all new parts. He has put 75 miles on the sled this year and today the clutch side melted the rings down again. the other side also showed sighns of over heating. We checked the temp sensor in my sled works fine. he got no light. we looked at the water pump belt, looks good, the blades on the pump itself work, oil pump is also working, thought maybe the coolers were pluged but they are not. so was not a issue either time it went down. just wondering if you guys can think of something we might have missed. thanks for any info you can give back.

 

[boxster7614]

Sounds to me like your jetting is too lean! What jets are you runing? What was the last reason he had to have it rebuilt, was it the same issue?

 

[retiredpop]

Sounds to me like your jetting is too lean! What jets are you runing? What was the last reason he had to have it rebuilt, was it the same issue?

I agree. This doesn't sound like a water temperature problem but rather overheating the pistons because of a lean fuel mixture. You need to get the carbs looked at and also check the carb boots to make sure they aren't cracked.

 

[HammsRMK]

if it was a lean issue wouldnt it put a whole in the top of the piston or on the side of the piston instead of just taking the rings out. also to let you guys know that the sled was running fine and then just shut down. can you guys think of anything else? thanks.

 

[retiredpop]

if it was a lean issue wouldnt it put a whole in the top of the piston or on the side of the piston instead of just taking the rings out.

Not necessarily. I have squeaked a piston a couple of times and it would be running fine then quit. I could start it up again and run it but on closer inspection I found I had transferred some piston material onto the cylinder wall. There are various degrees of damage done in a lean seizure.
Can you post a picture of your piston?

 

[HammsRMK]

ight thanks i didnt know that. ill see if i can get some pics tonight and get them on when i get home. thanks for the info.

 

[retiredpop]

Just curious as to what you found.

 

[HammsRMK]

so far nothing, we are thinking that we took some reed boots off my moms sled that had vfore reed, and they had a paper gasket that i didnt know about. Well when we put them on my bros sled we must have ripped one and didnt know it. the top of the boot and the bottom of the boot were not sealed tight and we think that it sucked more cold air in, it was -10 when we where riding that day. thats the only thing we can think of as we looked over everything else.