i need to know what my compresion should be. i cant find my manual anywhere, so i cant look it up.

Around 135psi

well my friends powder special 500 was reading about 85-90 each cylinder. we then tried it on mine and it said 85-90 for each cylinder. do you think his tester is broken? if its not, am i do for new rings.

Yeah,, I think the tester must be screwed,sled won't run with comp like that, try a better tester.

i dont know man, my other friends tester is reading 85-90 also. what do you think? i tore my motor apart and everything looks good. i guess i cant tell if the rings are bad or not? what do you guys think, should i replace the rings. the sled runs great, well i think so.


the only problem im having is that when it reaches like 6500-8000 rpm's sometimes it loads up and it takes awhile for the rpm's to drop below 5000 again. it only does this maybe about 3 times a ride, then it quits.

also when i start it, it will idle at 1500. once i rev it up and ride it and let off the throttle it idles at 2500, then after about 30-45 seconds it will drop down to 1500 again. whats causing these messed up idle problems?

How have you been doing the testing? How many pulls? Try it with a warm engine and a cold engine.

i tried it with a warm engine and then a cooled down motor. both 85. i let my friends do the testing. they both just screwed int he tester and pulled over the sled as hard as they could about 10 times. by about the 4th pull it was at 85 and wouldnt go above that.

I dont' think the sled should run with compression that low. If you believe the compression, do the top end (pistons and rings).

have you tried the tester on another sled??? you need about 90psi to make run shitty. If its at 85 you got problems. To check if the rings are bad, get a feeler gauge and check the ring gap. If its out of spec then your rings are woren too much and need to be replaced. Take a look at the cylinders and see if they have any big scracthes in them. how many miles are on that engine??? If there is more than 4000 on it I would rebuild it.

my cylinders and pistons look great. i can still see hone marks on them. the head has a few indents from ring shrapnel so the guy i baught it from must have blown it and rebuilt it. when i baught it the speedo said something like 2900 and ive only put on like 800. do you guys think ill be fine or what? i have no money to rebuild this motor so i need to know if its important that i do so or not.

You've tried 2 gauges, they both read 85, in both sleds? Any chance of checking them both in a third sled?
At the least, pull the "Y" pipe and get a look at the pistons.
Sometimes they can be in pretty bad shape without damageing the cylinders.
You've got no snow, and from what I can tell, the near future doesn't look too promising. Better to take the time now and check it out, re ring it if necessary, than ride it without knowing for sure and haveing to do cylinder work later.

what? we have like a foot of snow. i have the motor torn apart. i said the piston and cylinders are in excelent shape, did you not read any of this? alright guys.alright does someone want to run through the process of checking the ring gap? i know how to place the ring in the cylinder and what not.

OK,, somethings funny here,, two sleds with that low of comp, should act like a dogs, two testers showing the same, doesn't make sence, are they the same brand tester, I had 4900miles on my 500 and tested it at between 133-135, I don't beleive in tearing a motor down just because it has 3000 miles on it without good reason, are you holding the throttle wide open when you pull it over, I would still try a good name third tester if it were me.

i let my friends test it because they are the ones with the compression tester. they did NOT hold the throttle wide open. they never even touched it. they simply screwed it into the cylinder and pulled it over about 10 times. are you suppose to hold it wide open?


we used deans tester on my sled and deans. and used arts tester on just mine. everyone said 85psi. none of us held the throttle wide open either.

both sleds ran great too.

Compession should be done on a cold engine with throttle held wide open, but I don't know if it will raise it by as much as you need,never really tried it, but worth a try, I would still try a third good quality gage,to be sure before tearing anything down.

well i already have the motor torn down. ill put it back together and try it again. i also tried it on a warm motor.

oh just for the info, i tried the tester right after i got done riding so the motor was damn warm.

That would lower the comp for sure but I would still think it should be higher than that warm, if your motor is already torn down you might try your buddies sled again with a good tester or the proper way incase there is something wrong with your sled, no point in tearing it down twice, might be just as easy to throw a set of rings in now.

No way your sleds would run worth a shit with that low compression. I wouldn't worry about it, ride it and invest in a good compression gage. I've had good results with the craftsman compression gage, it's not that much $ either.

try testing the compression with the throttle wide open your problem is probably that, i think if you try this u should find that your compression should be around 120-140psi

well i slipped my cylinders back on and tightend them down a tinch and i can wiggle the pistons a little bit in the cylinder. the pto side piston also looks like it is a tinch worn on the exhaust side. the cylinders are perfect. the only thing that sucks is that i wont have any money what-so-ever to buy new rings/pistons for 3 weeks. the weird part is that i dont notice any lose in performance at all. only reason i tore the motor down was because the compression said 85. if i wouldnt have checked that for the hell of it this motor wouldnt of been apart until this summer. i think ill just put it back together beings i have some spare time and check the compression again.

well i went and picked up the compression tester then re-assembled my motor. i did a wet/dry test.

with the motor dry

pto: 85psi
mag:90psi


with a little oil dumped in the cylinders.
pto:120
mag:125



im kinda of curious because i should be okay to run this shouldnt i? i mean the motor is being oiled as i run it.