help with compresion

[scteacher7272]

I tested my 1988 Johnson 150 and each cylinder tested at 80 pounds of compresion on the button. Is this too low and does anyone have any suggestions on how to increase the compresion
Thanks

 

[5150abf]

Re: help with compresion

Welcome to iboats.

If that was cold you are okay, it should go around 90+ hot which is good, if that was hot maybe not the greatest but still okay.

All cylinders are the same which is the big one, if the engine runs okay, and it should you are fine, it may be your compression gauge just reads low.

If you haven't do a decarb and that should bring it up a little btu I think you are fine either way.

 

[emdsapmgr]

Re: help with compresion

I would think 90 lbs would be typical compression, so you may be a little low. The XP/GT 150 models had higher compression by 10-15 lbs. I'd agree that you should try to decarb the engine if it has not been done recently. The decarb process can reduce carbon accumulation around the rings and pistons. This decarb process can increase compression somewhat and can also improve idling characteristics. If you see any improvement, it won't hurt to the decarb a second time. Bombardier makes a product called Engine Tuner specifically for this purpose. Considering the poor quality of fuel today, it's not bad to decarb annually.

 

[Chris1956]

Re: help with compresion

Do you know if your gauge is accurate? Since all cylinders are the same, the motor is likely fine, and the gauge is reading low.

 

[R.Johnson]

Re: help with compresion

I don't think I've ever seen two guage's read alike.

 

[kenmyfam]

Re: help with compresion

I'm 100% on board with the gauge accuracy folk. Even compression is important. Can you check it with another gauge for comparison ??
Decarb is never a bad idea though.