compression

[rhcotton]

What are some of the reasons a outboard will lose compression in one of the cylinders? My outboard is a 1985 90hp. I have 120,120 on one side. I have 115,95 on the other side. Also what potential effect will this have on performance. Thanks for any help or suggestions.

 

[Dhadley]

Re: compression

If the numbers are consistant on each side but different fron port to starboard it could be a non-matching head set. If your numbers are lower on the starboard side and you have matching heads, the rings could be starting to coke up which causes them to stick in the groove. Thus lowering static compression. <br /><br />If you run a sticking ring long enough it will break off one end. Decarb should take care of this if the rings are not broken yet. If your propped in the low 5000 range I would suspect this.<br /><br />It could be a leaking head gasket.

 

[rickdb1boat]

Re: compression

Wear on the cylinder walls, rings that are partially stuck with carbon in the grooves, not making good tight contact with the cylinder walls. You would lose power, of course, if compression is not up to par. Try a decarb on those cylinders and let us know if it comes up.