Engine Problems

[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.

 

[m8inthemtns]

It sounds like it is running lean.

 

[clodhopper]

I agree with the post above, Water temps won't melt pistons & rings. More info on the sled would help. Carbs or efi?

 

[HammsRMK]

carbed its a 2002 800 rmk. i have the same exact sled and we are both running the same jets and i have not had a problem yet. we have both had the sleds for 3 years and it melted down last year from what we thought was heat and this time thats what we think too but not sure. i beleive we are running the right jets. i cant remember what they are off the top of my head.

 

[HammsRMK]

also just wondering if its a lean issue wouldnt it melt a whole in the piston somwhere, instead of scoreing it and melting the rings? also a note the sled was running fine and then just shut down. we started it back up but did not sound right so pulled it home. any more thoughts? thanks for you help.

 

[maddog21]

is the jets set for 0-3000 feet? what about needle clip? it has to be in #4

 

[HammsRMK]

i beleive its for 0-3000 but not sure on the needles ill check that out and ill get the jet size when i get home.

 

[m8inthemtns]

Both sleds same jets, may be a bad crank seal or crank case seal. A small air leak will lean it out. You can test it with a can of starting fluid.

 

[rdr99]

Check the carb boots.

 

[LRD]

Lean will melt the edges of the pistons, stick the rings, also will do a 4 corner score on the piston again sticking the rings and wrecking the cylinder walls.

Lean caused by water in the fuel, a blob of water will plug a jet and no fuel goes through. Crank seals leaking will cause lean, need to pressure test crankcase with carb throats and exhaust ports plugged at about 5 psi. Reed cage boots can look good and leak like a sieve. Carb jets plugged with crud over summer etc etc.

Whenever I have a cylinder go down I drain the fuel out of the carbs into a white plastic container (koolwhip is perfect) if theres water you can clearly see the blobs floating, or foreign material, blacks specs etc.

Sounds like you fixed the symptom the first time and not the cause.

Good Luck