Low Comperssion-Is it time for a rebuild?

[Ruff Cut]

I did a compression test on my 20006 RXP 215 hp. It has 175 hrs on it. The SC was rebuilt at 120 hrs. Compression test came out poor. From front to rear-105-95-95. I was using a brand new gauge. It may be off but not that much. I thought about trying another tester. Does it matter test hot or cold? The ski runs great. Hard acceleration right to 68 mph. I do plan on rebuilding the SC this winter. But now may need to do the top end also. Any recommendations.... Thanks..

 

[Coastiejoe]

SC engines are a "low compression build". I'd have to look up the number to confirm what they should be.

And yes, ALWAYS try a different gauge when you have low ratings. We have seen it many times. Rebuild an engine just to have similar numbers after the rebuild. And then use a different gauge and the numbers are good.

 

[IDoSeaDoo]

My 185 sc got like 150psi... i do not remember seeing a compression test spec in the manual though, anyone know what it ought to be?

 

[ski-d00]

Compression can be all over the place on 4tecs, especially the sc models, and still run perfectly. A better evaluation of engine health is a leak down test.

Your valves or rings may leak a little bit when cranking but then seal up under higher rpms which gives you perfect performance.

If it runs fine, don't do anything. It is not like a 2 stroke where compression is everything. 4 stroke compression readings can be deceiving since knowing compression at like 200 rpms during cranking means very little. It's good for discovering catastrophic failure but not much more. Do a leak down test but I'll bet you get good results.

Average normal compression is 110 - 140 on scs but have seen them lower and higher and still run fine. Higher on NA models like 130-160.