compression test

[jeff winter]

Im out looking for a replacement motor.........<br /><br /> I ran a compresion test on a 2 stroke 91 Evinrude 50 hp........ Now Im not a two stroke mechanic but I rebuild automotive 4 stoke engines everyday........<br /><br /> first cylinder 60 psi warm<br /><br /> second " 55 "<br /><br />Now I gotta believe that these engines run a bunch more compression than that. Im used to 130 to 150 PSI. I walked away from that motor. What is the normal compression numbers on a 2 storke like this? Thanks, Jeff

 

[phototom1]

Re: compression test

Jeff
I am no mechanic and mybe some one else will step in but from all I have read on this and other forums I would think around 120-130 with no more than a 10% difference between cyls. I have seen some post stating 95 and up is OK.
Tom H

 

[91cajun]

Re: compression test

Sorry to highjack this thread but, something is wrong with iboats and I can't start a new topic. I looked in the FAQ section and couldn't find the procedure for doing a compression test. I know I have seen it here before but, the search tool needs to be improved. Do I need to remove all plugs and do one cylinder at a time or can I just pull the boots off the plugs and do one plug at a time?

 

[Walker]

Re: compression test

Jefrf, is it hard to start. I agree with mrtoolsu. Is you compression guage accurate. Is it a screw in type or the type with the rubber boot you just push in and hold??

 

[ezeke]

Re: compression test

There is a lot of information here about compression.

Try copying this link to your browser without the quotation marks:

"http://www.outboardrepairs.com/compression/"