Acceptable engine compression for 215 hp and/or 255 hp rotax 4tec engines?

[Cathylongasta]

Hi, going through a check list and one being engine compression?
What is the acceptable engine compression level for the 215 hp or 255 hp rotax 4tec engines. Also is there a minimum acceptable compression limited for its service life?

[Snoman]

125 to 135 psi....

10% difference between any cylinder is time to consider rebuilding/fixing....

[Cathylongasta]

So I would guess that 122 on 1, 110 on 2 and 120 on 3 would be considered in need of a rebuild? Thanks

[Snoman]

do a leak down test first to see were your loosing compression from...you could have valves that are not sealing right that could cause your compression to drop also...Once you do a leak down test you will know for sure if the rings are going or if the head needs work..this will save you a ton of time and money rebuilding something that may not need to be rebuilt

[Cathylongasta]

Is there a minimum? For example if the readings were 100-100-100.. Or is the minimum acceptable 125psi? Thanks

[Snoman]

me personally dont like seeing it below 120..but thats just me...

[ou812]

My 07 RXT with a 2 rude setup running 76-78 mph was running 115 to 120 psi for a few years. Racing endurance and hard rec riding, never an issue.

[espritv8]

cylinder 1 = 115psi
2= 125
3= 125

need to be worried?
I checked with the engine cold though...

[tiderider]

cylinder 1 = 115psi
2= 125
3= 125

need to be worried?
I checked with the engine cold though...

Your still okay.
115 x 10%=126.5

126.5 is greater then the other 125 so your still good.