Ok, Need Your Opinion On Compression Please.....

[Quadaddy]

I just checked the compression on my sons 2002 Polaris Trailblazer 250. Cold was aprox. 87psi and warm was about 80. Does this sound reasonable to you ? Thanks for any response. :rider:

Thats a 2-stroke isn't it? I know that the Polaris 4-strokes are running between 70-90 lbs. I check imto it further.

Ok, heres the scoop.........You should be at 115-120. Looks like it's time for a rebuild. :huh:

[Quadaddy]

Originally posted by paulzaho@Oct 16 2004, 03:12 PM
Thats a 2-stroke isn't it? I know that the Polaris 4-strokes are running between 70-90 lbs. I check imto it further.
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Yeah...2 stroke.

[Quadaddy]

Originally posted by paulzaho@Oct 16 2004, 03:21 PM
Ok, heres the scoop.........You should be at 115-120. Looks like it's time for a rebuild. :huh:
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Where did ya find the info ?....
I just recently got back into quads and I'm looking for good info and parts sites.

I think you had better either pick up a repair manual or make some calls to see what polaris claims is the min comp.

Have to think 80psi isnt good since most of the two strokes I have known of the comp etc seem to be from around 150-200 (mostly 250r's after a rebuild) and many 4strokes show from 115 or 120+ and they have a issue with valves etc too.

One last thing I am thinking you may have the numbers backwards cause it should be higher when heated up to operating temp cause the internals expand and the rings should seal better.

[satrnfreak]

Quick question, when you did compression check, did you open the throttle all the way while cranking/pulling?? If you did not, you actually didnt draw in enough air to compress, and will get lower numbers...

My Trailblazer when it was healthy had 170psi, it now has 90 and will not start off of electric start, will only pull start(sometimes). Id say if you had the throttle open, and cranked it good, put some oil in the cylinder and see if it goes up. If it does, you are gonna need some rings/topend rebuilding.

fREAK

[Quadaddy]

Originally posted by satrnfreak@Oct 17 2004, 09:37 AM
Quick question, when you did compression check, did you open the throttle all the way while cranking/pulling?? If you did not, you actually didnt draw in enough air to compress, and will get lower numbers...

My Trailblazer when it was healthy had 170psi, it now has 90 and will not start off of electric start, will only pull start(sometimes). Id say if you had the throttle open, and cranked it good, put some oil in the cylinder and see if it goes up. If it does, you are gonna need some rings/topend rebuilding.

fREAK
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Yeah, did it both ways......throttle open and closed. It was only a couple psi higher with w.o.t. The main reason I decided to check it is cause it was having trouble starting after it was run for awhile. After reading another post, somebody suggested that it might be a low compression situation. I did raise the idle speed a bit and it seemed to help but i'm thinkin I'll probably go thru the top end maybe this winter...... Thanks