skeeter2010
Member
What should the compression be on a 01 xcsp 500 I have a cheap tester and I had about 95 PSI on both cyclinders any thoughts the sled runs and starts fine
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compression testing
- Thread starter skeeter2010
- Start date
Not being familiar with Polaris, I don't know what it should be. For my sled, that would be pretty low. First thing I'd do is check it with another gauge (a known good one, if you have access to it) and compare. From what I hear, readings can vary widely from one tester to another.
That both cylinders are similar is a good thing. Also, take cold and hot readings (cold being after about 30 seconds of run time, hot being getting the engine up to operating temperature).
That both cylinders are similar is a good thing. Also, take cold and hot readings (cold being after about 30 seconds of run time, hot being getting the engine up to operating temperature).
Last edited:
cuzzinolaf
Well-known member
Get a good tester and try again. Rule of thumb is to have over 100 psi.
harvest1121
Well-known member
I rented a cheap one before they both said the same. They were about 95 also but really had 140 once they were checked with a good one.
mjkaliszak
New member
A compression test by itself won't tell you much unless you see unequal numbers between cylinders.
If it runs and starts fine (and your compression numbers are equal) you shouldn't do anything to your machine based solely on a compression test.
Mike
Have a POO 600HO when i checked it cold it read 120 120. Kind of confusing since I would rather have seen 150 150. When I asked on-line someone told me that's what that sled should be . I would think that those are low ( in my book ) if your reading was good. it just means that the motor is tired.
skeeter2010
Member
Yes it was held wide open for the test
My guess is that it may need a set of rings I am selling it and the guy that looked at it wanted it tested. My guess is he will take it just the way it is. Heck it runs really good and it has 6000K on it put in a set of rings for 100 bucks and run it
My guess is that it may need a set of rings I am selling it and the guy that looked at it wanted it tested. My guess is he will take it just the way it is. Heck it runs really good and it has 6000K on it put in a set of rings for 100 bucks and run it
Rings are made from some of the highest grade materials money can buy these days except for some of the cheap import stuff. Maybe not so true twenty years ago, so the need to install new rings has diminished greatly in the last twenty years.
Rings on a snowmobile don't normally wear much unless you intake dirty air, something that shouldn't happen on a snowmobile as long as you operate it primarily on snow. Snowmobiles, and things like outboard motors, don't need air cleaners as long as you stay on the snow (or a lake with your outboard). Hard to find dust and dirt on a snow cover landscape or in the middle of the lake.
All in all, if you have low compression numbers first I would consider the fact that the gauge you are using has probably never been calibrated (even from the manufacturer) and second that you may have some other damage from lean conditions, dirty air and/or fuel both of which if not remedied will just smoke another set of rings.
Rings on a snowmobile don't normally wear much unless you intake dirty air, something that shouldn't happen on a snowmobile as long as you operate it primarily on snow. Snowmobiles, and things like outboard motors, don't need air cleaners as long as you stay on the snow (or a lake with your outboard). Hard to find dust and dirt on a snow cover landscape or in the middle of the lake.
All in all, if you have low compression numbers first I would consider the fact that the gauge you are using has probably never been calibrated (even from the manufacturer) and second that you may have some other damage from lean conditions, dirty air and/or fuel both of which if not remedied will just smoke another set of rings.
compression test
one of my dads 4 wheelers wasnt running right so took it and i figured it had a bad cylinder .i did a compression test with a good gauge and it was 125 .but i knew it had to be bad i had seen it before .so i took it apart anyway .it was very worn .so a little warning that the compression test does not tell all .
one of my dads 4 wheelers wasnt running right so took it and i figured it had a bad cylinder .i did a compression test with a good gauge and it was 125 .but i knew it had to be bad i had seen it before .so i took it apart anyway .it was very worn .so a little warning that the compression test does not tell all .
be careful!!!
I told a freind to do this. He took it one step further and added to someone elses advice to put the other s/plug in. He even put the plug wire on for good luck. When he told what kind of damage the sled did to the back of his garage I asked him what the H_ _ L he was thinking? His response was "Well, when I foul a plug the motor will barely run. I didn't think it would take off through the back wall of my garage".
Reality is: 100 psi for a 2 stroke to run
10% difference between cylinders indicate problems
Each comp test should be the exact same no matter what your pref
Did you tape the throttle wide open when
you tested.
I told a freind to do this. He took it one step further and added to someone elses advice to put the other s/plug in. He even put the plug wire on for good luck. When he told what kind of damage the sled did to the back of his garage I asked him what the H_ _ L he was thinking? His response was "Well, when I foul a plug the motor will barely run. I didn't think it would take off through the back wall of my garage".
Reality is: 100 psi for a 2 stroke to run
10% difference between cylinders indicate problems
Each comp test should be the exact same no matter what your pref
be careful!!!
I told a freind to do this. He took it one step further and added to someone else's advice to put the other s/plug in. He even put the plug wire on for good luck. When he told what kind of damage the sled did to the back of his garage I asked him what the H_ _ L he was thinking? His response was "Well, when I foul a plug the motor will barely run. I didn't think it would take off through the back wall of my garage".
Reality is: 100 psi for a 2 stroke to run
10% difference between cylinders indicates problems
Each comp test should be the exact same no matter what your pref
ALLWAYS REMOVE THE KEY AND HIT KILL SWITCH!!!! ALLWAYS!!!!
Did you tape the throttle wide open when
you tested.
I told a freind to do this. He took it one step further and added to someone else's advice to put the other s/plug in. He even put the plug wire on for good luck. When he told what kind of damage the sled did to the back of his garage I asked him what the H_ _ L he was thinking? His response was "Well, when I foul a plug the motor will barely run. I didn't think it would take off through the back wall of my garage".
Reality is: 100 psi for a 2 stroke to run
10% difference between cylinders indicates problems
Each comp test should be the exact same no matter what your pref
ALLWAYS REMOVE THE KEY AND HIT KILL SWITCH!!!! ALLWAYS!!!!
G
G
Guest
If the readings are close it is fine. Whether it is 90 or 120 it really does not matter. It also does not matter if you hold the throttle open or not. Just do the same for both holes. All you can really learn from a test like like this is if you have some severe scoring or a stuck ring. When the engine is actually running the compression will increase. Yes, it does take a magic compression # to fire. Way back when on our old triple triples it was not uncommon to stick a ring on a cylinder. You could put a compression tester on the thing and it would show something like 110,113,85. You could start it and it would run on two cylinders. If you got on it and rode it things would heat up and the third sick cylinder would begin firing again. Not a good long term plan to keep riding this way but in many cases the damage was done. If there are no problems or modifications I would not even consider re-ringing a sled with less than 5000 miles. Especially based on a compression test.
G
G
Guest
Nevermind. It is an '01 500 XCSP. They will run forever unless you are really mean to them.
mjkaliszak
New member
I told a freind to do this. He took it one step further and added to someone else's advice to put the other s/plug in. He even put the plug wire on for good luck. When he told what kind of damage the sled did to the back of his garage I asked him what the H_ _ L he was thinking? His response was "Well, when I foul a plug the motor will barely run. I didn't think it would take off through the back wall of my garage".
Reality is: 100 psi for a 2 stroke to run
10% difference between cylinders indicates problems
Each comp test should be the exact same no matter what your pref
ALLWAYS REMOVE THE KEY AND HIT KILL SWITCH!!!! ALLWAYS!!!!
Back in the day.... about 30 yrs ago, I can tell a story of how we were squirting oil in the cylinders to check the rings on a Mopar, never dawned on us to not put the plugs back in , so we loaded up the cylinders with oil, went to check 1 , turned the car over, and KABOOM... after the mushroom cloud cleared, and our buddy was still standing with the " trouble light in his hand ".... we blew the valve covers right off the motor. Good thing we didn't mess up Socko's Snap on Compression guage, he would have kicked our arse's... That was a Hoot at the time. It did scare the crap out of us.... such is life, just when you think you got it "going on" a lesson in humility occurs !