Compression

[springbok]

What should the compression be on a <br />1988 25hp Evinrude?

 

[mrn714]

Re: Compression

I believe that it is 125 - 130 range, but my book is at the house. What are you getting now?

 

[rickdb1boat]

Re: Compression

It's not what it should be. It's the difference between the cylinders that count. No more that 15% difference. 90-100 PSI would be good, but that's just a figure. Idon't think you will find a difinitive answer, as all motors vary.

 

[G DANE]

Re: Compression

I´ve had three of the above motors, they had in the 122 - 130 PSI range. They all had compression figures within 2 psi on both cylinders. VERY good motors.

 

[8up]

Re: Compression

Is it true that comp. readings on say a v4 for example, that it's the difference between the top and bottom cyl. on each side (Bank)? Did I explain this O.K.?

 

[DJ]

Re: Compression

8up,<br /><br />On a V-4, you still want to compatre all four. The 10-15 psi range rule still applies.

 

[OBJ]

Re: Compression

Bup...compression on a cylinder is just that. It's own individual compression.<br /><br />Generally speaking, 90+ on a cylinder is great. If all cylinders are within 10 to 15% of each other, this is condidered good. But like Rick pointed out, this is just a figure.<br /><br />Example, if a V4 has 80 to 85psi on each cylinder, I would say that ain't bad and would not see any reason to do any rebuild. Just as long as the owner takes care of the engine and does the right things, tune ups, decarbs and such, he should get a long life from the engine.<br /><br />It's when you see readings that are way outta range from each other that it's time to start worrying.<br /><br />I hope I explained that OK. Not real great with words..