Johnson compression

[deezelteck]

Hello all,
I have a 1959 35HP johnson. I took it out after rebuilding the carb and it would never reach WOT. It would bog down and smoke, after adjusting on the carb all day I checked the compression. The compression is about 110psi on both cylinders after about four complete rotations, Is this a good reading or to low? Thanks to all that help.

 

[tashasdaddy]

Re: Johnson compression

great. did you replace the impeller. did you use a kit for the carb. try the carb adj again follow this, 2nd section. http://forums.iboats.com/showthread.php?t=167352

 

[jbjennings]

Re: Johnson compression

Almost for sure it's a spark issue and you're only running on 1 cylinder. I believe it would run o.k. with 110 lbs. I believe about 135lbs. would be ideal but I'd almost bet that compression is not your problem. From my miniscule experience, even but low compression would be most noticeable on idle and not wide open throttle. Wide open throttle it would still run pretty smooth just not have as much power. So rest easy, it's something else than compression.
JMO,
JBJ

 

[deezelteck]

Re: Johnson compression

Thanks for the help guys. I did put in a carb kit, and the adjustment procedure is almost exactly as it is in the book. Still after readjsuing the carb and checking to make sure that I was getting spark to both cylinders it boggs and when I idle it down it somtimes dies. Early this year I put a complete tuneup on this engine new impeller, lower unit seal kit, clutch, spark plug wires points, and carb kit. Still it runs very weak and smokes more than normal. I don't know what gotten into this thing thanks for the help.

 

[F_R]

Re: Johnson compression

I agree you have an igniton problem. Remove and ground one plug wire and see how it runs. Then do the same with the other one. Results should be the same, but I'll bet they aren't. Therein lies your porblem.

Are you checking the compression with the recoil or with electric starter? If recoil, you will get false readings unless you disable the compression relief. And crank it till the reading won't go up any higher. But as already stated that is not your problem anyway.