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Discussion Starter · #1 ·
So after the season was done we compression tested the sleds in our group. Most of the sled were around 120 or 125 (mainly ski doos) I have a 1998 Indy 500. Mine was 90, but it was 90 in both cylinders. Its not like the sled is slow either itll still do 85, and can smoke any of the other 500's in our group to 20 or 30. Any knowledge on the compression would be great.
 

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Should be higher then that. While it's the off season you may want to put new rings and rebuild it. If you do it yourself it won't cost much. Or if it's running fine then keep driving it but the last thing you want is for it to be winter and have your engine apart.
 

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Discussion Starter · #5 ·
Yeah, This is my second season with this sled, and it runs fine, doesnt smoke, still pulls like it has good compression, like i said even at 60 I can crack it wide open and it still pulls good. This is why i found it weird that the compression is low but it still runs like a top (knock on wood).
Thanks for the info
 

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I don't know too much about this kind of stuff, but dont those smaller engines run a little lower compression?
 

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^x2 yea just put new rings on it and gaskets on it and itll run fine.
 

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Discussion Starter · #9 ·
True true, and thats simple enough, but what I dont understand is how it runs so well with such low compression. It doesnt smoke any extra either.
 

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How did you do the compression check? Plugs out, throttle wide open, three or four pulls on the recoil. If it is still at 90 it is time for some work. Check the piston clearence. If it is over .0078" it will need new pistons and cylinders bored to fit. If not you should re-hone and put in new rings. Putting in new rings without re-honing is fixing something half-assed.
 

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did you guys test your sleds with the same gauge they can be off up to 20psi depending on age and what not, but at work we tested my ZRT and my bosses gauge he used on model-A's (example for age) said it had 90psi across the board well I got my fancy just bought a month ago snap-on comp. gauge and all 3 cylinders where at 119-120psi
 

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Discussion Starter · #12 ·
Thanks again guys, I have looked into doing the pistons and rings and such, Im going to check my brothers sled first and se what his compression is at. Triple u bring up a good point I will try another gauge.
 
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