Checking Compression

[Snort]

Hi,

I have a 2005 Summit 800. Has been running fine but I thought that I might check the compression.

Can someone tell me the proper steps to do a compression check?

What values are good/acceptable/poor?

Thanks

 

[eazyduzit509]

Im not sure what your 2005 presure needs to be at, but... When your checking the compression, obviously pull BOTH the plugs out and screw in you tester. I have read, been told and have always tested with THREE (3) pulls. So, pull it smooth and hard 3 times and look at your readings. IF I were to GUESS I would say your compression should be between 120-150. REMEMBER! Thats just a guess. Hope this helps.

Just looked up that YOUR 2005 Summit 800 should have a compression of about 130. Just from what I looked up sounds like if your between 125-135 your just perfect! Leme know what its at.

A good sighn that you have a problem is if the compression is bellow 100. Not sure if its bad to have exceptioally high presure, (ex-145 psi). I also know your compression WILL change with a HOT and a COLD engine. I THINK your sappose to check it when it cold. Because the engine heats up your inerd's (pistons, rings, cylinders) will expand, thats why you will get different readings with hot and cold. Good luck man!!!

 

[Snort]

Don't want to sound dumb but I am not sure of the obvious reason to pull both plugs first.

 

[winter brew]

Take out both plugs so it's easier to pull over. Hold throttle open a bit and pull until the gauge stops going up.

 

[eazyduzit509]

Ah, brew is right, you also need to hold the throttle wide open when pulling. Just forgot. Thanks brew. (several mechanics told me WOT when testing compression.)

 

[Snort]

Pulled both plugs and pulled until the gauge stopped building

120 PTO
130 Rewind

 

[eazyduzit509]

Sounds perfect! Put those plugs in and hit the mountain!!!

 

[Crasher]

Even though you compression checks out, if you have not changed your rings, you need to.
I have pulled down several 800 Doos and every one of them from 03-05 had flaking rings.
If you don't believe it, pull the y-pipe and take a look at the rings. You will see small pieces of ring missing between the top of the ring and the bottom. They are a laminated looking ring, Hard ring on top edge, soft flaking in the middle and hard on the bottom. The hard top and bottom still make it read good compression but you are not far from a major time bomb.

 

[High Voltage]

Even though you compression checks out, if you have not changed your rings, you need to.
I have pulled down several 800 Doos and every one of them from 03-05 had flaking rings.
If you don't believe it, pull the y-pipe and take a look at the rings. You will see small pieces of ring missing between the top of the ring and the bottom. They are a laminated looking ring, Hard ring on top edge, soft flaking in the middle and hard on the bottom. The hard top and bottom still make it read good compression but you are not far from a major time bomb.

My 04 rings looked ugully with only 500 miles on them !

 

[ak]

A 800 Ho Summit with good rings, should be close to 150 if not 150 Lbs of compression.

 

[Summitstef]

I just replaced my rings about two weeks ago on the "wifes" '04. Compression before switch over 125 PTO & Mag. Compression after ring replacement 148 PTO and Mag and the sled has 2250kms. The pistons look great.