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Discussion Starter · #1 ·
Just for kicks I decided to get a compresion test kit, screw in style, and test my MXZ 700. I just put it back together and put 174 miles on it. I checked it warm and WOT, got 125 PTO, 130 Mag. As a comparo I decided to test my 8000 mile 583 and got 130/135. I went with the number 5 base gasket on the 700, should I have gone w/ the thinner one? It rips and runs great, but I figured on higher numbers. (Pistons are stock and coated. PTO is old, Mag is spanken new, new rings both.)
 

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At the beginning of this season, I checked my 800:

Hot, WOT, 3 pulls I got 135/131.
Hot, WOT, max pulls I got 146/140
Cold, WOT, 3 pulls I got 145/140
Cold, WOT, max pulls i got 157/146

I'm not sure if there's an 'official' way to do a compression test, but I know that you can get big differences in the results depending on how you do it...
 

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I usually test mine cold, and crank until the compression stops rising.
 

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Discussion Starter · #5 ·
Would my base gasket choice effect these numbers? What about ring seat? With only 174 miles on new rings are they seated yet/enough and will my test show higher later?
 

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The rings should be seated already.

A thinner base gasket will increase compression, but could cause detonation. There are other folks on here that could likely explain it better than I can.
 

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Your #'s sound fine to me. Don't sweat it. They vary a LOT depending on barometric pressure, temperature, humidity, brand of compression guage, elevation, etc, etc, If it's running good, just drive...
 

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Originally posted by craze1cars@Feb 5 2005, 11:20 PM
Your #'s sound fine to me.  Don't sweat it.  They vary a LOT depending on barometric pressure, temperature, humidity, brand of compression guage, elevation, etc, etc,   If it's running good, just drive...
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well that is right inline with what my 700 had new and now after a topend last season.I personally have never seen a 700 above 135,not saying its not possible.I really use the numbers from new till now,using the same gauge, to monitor loss.
 

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I have a 600 it runs between 145 and 150 for compression. I don't believe in to much of a break in. I rebuilt mine 3 times over the years and after about an hour I consider it broke in. You are prob fine it might be a good idea to slap a set of rings in that bad boy. It will be rippin.
 

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I have a 600 it runs between 145 and 150 for compression. I don't believe in to much of a break in. I rebuilt mine 3 times over the years and after about an hour I consider it broke in. You are prob fine it might be a good idea to slap a set of rings in that bad boy. It will be rippin.
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Dude I never put rings on a used piston.The piston fills the hole and if it is worn and you have it apart put anew piston in it.Thats my opinion.
 

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fresh top end 2001 mxz 700 has about 800 miles 130 psi +- 2psi.
When I put the new pistons and rings in after a couple hundred miles got the exact same #. Sounds good to me man.
 

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At the beginning of this season, I checked my 800:

Hot, WOT, 3 pulls I got 135/131.
Hot, WOT, max pulls I got 146/140
Cold, WOT, 3 pulls I got 145/140
Cold, WOT, max pulls i got 157/146

I'm not sure if there's an 'official' way to do a compression test, but I know that you can get big differences in the results depending on how you do it...
Mines got 150 each side but won’t fire not even off gas in the cylinders mxz 700 watercross sled with crank shop twin pipes
 
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