compression on 93 johnson 225

[answer21]

I had my 93 johnson 225 engine rebuit about 3 1/2 months ago and today I cranked it up for the first time. I ran it for about 20 to 30 min. and checked the compression. 5 pistons had 100 and one had 90 is this normal comp for this engine after being rebuit and will it go up after it is broken in. Thank for the advice.

 

[NathanY]

Re: compression on 93 johnson 225

For a freshly rebuilt engine, that is very low compression. It should be around 130-150. I would definately be taking that one back. Provided that the break in period is over. Engine compression will change during break in, but not by 50lbs.

 

[walleyehed]

Re: compression on 93 johnson 225

I've got the same situation with my 97' 115. I just rebuilt it this spring and have about 20 hours on it now and I've got 3 95's and 1 at a 100lbs.....is that bad for a 115 (Johnson)????<br /> Seems like my old 77' was around 115-120lbs.

 

[Dhadley]

Re: compression on 93 johnson 225

90 to 100 is not bad for a looper. Especially a closed deck. It depends on which heads were used and if they were cut and how much if they were. <br /><br />Cross flow V4's generally had more static compression. It has to do with port area, port timing, squish band, chamber cc's and things like that. <br /><br />Good luck!

 

[walleyehed]

Re: compression on 93 johnson 225

Yea, mine is a crossflow......I figured it should be 130 with the stock heads..no luck.<br /> Runs great-just won't pull the prop I think it should.......guess I got another project come snow-fall........