Compression check ?

[1Fast68]

06 REV 800 HO, Assuming low miles and no ring issues how many PSI should I see on the gauge Hot and Cold?

 

[shonuff]

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.

 

[sledsrock]

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.

 

[eddy]

Seattle sea level 155 cold both sides

 

[1Fast68]

Thanks for the replies everyone. Tells me everything I wanted to know.