johnson compression

[5string]

I have a 1996 Johnson 48 special and I need to know about what the compression should be? Do I have to warm up the motor first then check compression? The reason I'm checking is it seems that I don't have as much power as I used to have, the boat won't even plane with 3 people in the boat and I checked for water in the boat and left the lower plugs out and tilted up for a few weeks.I replaced the fuel pumps and it seems to run fine, sounds like it is running wide open and I checked the prop. all is good.

5string in NC

 

[jbjennings]

Re: johnson compression

The motor does not need to be warm to check compression. I think it would be better to check it cold, actually. It would probably be best for you to just check it, and post your readings. Then, someone who really knows their stuff will tell you if it's o.k.. They'll tell you quickly, by the way. I would be looking for over 100psi and the same on all cylinders or close to it. (within 10% of each other is kind of "standard") OMC doesn't provide factory compression specs.---I've already asked....
Good luck,
JBJ

 

[tashasdaddy]

Re: johnson compression

yep!!!