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Compression check ?

1Fast68

Well-known member
Lifetime Membership
Nov 26, 2007
699
124
43
37
Renton, WA
06 REV 800 HO, Assuming low miles and no ring issues how many PSI should I see on the gauge Hot and Cold?
 
S
Nov 26, 2007
184
14
18
Lakewood, CO
Every sled is different and elevation is a factor.

For my last compression check on my 06 Summit 800 was both cylinders were at 135 cold and 128 hot. This is a Denver's elevation According to the information below it sounds like I need new rings but I don't think I do since they are both exactly the same for the hot and cold reading, which is most important. Plus the sled pulls great. Different gauges will give different readings also.

Here's how I take the test:

1) Start the sled and let it run for about 30 seconds and kill engine
Take compression with 6 pulls at wide open throttle.
What are the values
2) Start the sled and let it run until coolant is at operating temp. shut off and check compression with 6 pulls at wide open throttle.

Cold compression- 5lb or greater difference from mag to pto.
Hot compression- 7 lbs or more less than when it was cold you need rings.
Hot compression- 10lbs or more less than when it was cold then you need pistons.
 
S

sledsrock

Well-known member
Nov 26, 2007
1,826
510
113
Grand Junction, Co.
Every sled is different and elevation is a factor.

For my last compression check on my 06 Summit 800 was both cylinders were at 135 cold and 128 hot. This is a Denver's elevation According to the information below it sounds like I need new rings but I don't think I do since they are both exactly the same for the hot and cold reading, which is most important. Plus the sled pulls great. Different gauges will give different readings also.

Here's how I take the test:

1) Start the sled and let it run for about 30 seconds and kill engine
Take compression with 6 pulls at wide open throttle.
What are the values
2) Start the sled and let it run until coolant is at operating temp. shut off and check compression with 6 pulls at wide open throttle.

Cold compression- 5lb or greater difference from mag to pto.
Hot compression- 7 lbs or more less than when it was cold you need rings.
Hot compression- 10lbs or more less than when it was cold then you need pistons.

Great reply!!

Everyone needs to remember that elevation matters as well as all comp testers read differently.
 
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