Compression on 135 hp Evinrude

[Jeff2012]

Hello my friends,<br />Does anyone know what the compression should be on a new 1974 135 hp Evinrude? And what would be considered good compression now on the same used engine now?<br />Thank you.

 

[emdsapmgr]

Re: Compression on 135 hp Evinrude

An overhauled 1979 85 horsepower engine has 125 pounds compression. In good shape, the 135 should be in the same range. It is important that the compression on each cylinder be within 10% of each other. As total engine compression decreases, you will lose horsepower/performance.

 

[Jeff2012]

Re: Compression on 135 hp Evinrude

Shouldn't the compression be a little higher on a 135?

 

[ezeke]

Re: Compression on 135 hp Evinrude

Bigger piston and cylinder on the 135. Same starter motor and flywheel. I would expect not. <br /><br />The reading varies with elevation, too.

 

[Cricket Too]

Re: Compression on 135 hp Evinrude

Compression #'s have nothing to do with the HP of the motor, although as you lose compression you will lose hp and performance, as was said, but it does not mean that high HP has high compression and vice versa. I have an old '75 70hp that has 130psi of compression on all 3 cyl. I also have a 200hp with 100psi on all 6cyl and has been like that since the factory. As long as the compression is equal or with 10%, your fine. Decarb it a couple of times and you may get a little bit more compression on it.

 

[mitchell6]

Re: Compression on 135 hp Evinrude

Ive got about the same motor it's a Johnson 135, the compression on it is 150

 

[G DANE]

Re: Compression on 135 hp Evinrude

Not that there's any sence in diskussing this, but I dont think there ever was a crossflow with 150 PSI static compression with a true reading gauge. Gauges can vary a lot. The loopers can have compression up to the mentioned 150, but crossflows usually never comes over 135. If you find one with 125 on all four, be happy.