JamesC-120 204 #1 Posted July 6, 2014 (edited) I have an onan 16hp engine that has bad compression.(75psi and 60psi). It runs perfect and starts instantly every time. It does not burn any oil but does smoke when revving it up. It lacks power. Is it just worn out and needs a rebuild or does it just need new rings? Could it be broken rings? What is making it have low compression? Thanks Edited July 6, 2014 by JamesC-120 Share this post Link to post Share on other sites
WH nut 553 #2 Posted July 7, 2014 I would start by pulling the heads and decarbon before you condemn it. Share this post Link to post Share on other sites
Desko 624 #3 Posted July 7, 2014 In best case scenario is all it need is a hone job rings and valve adjustment. Share this post Link to post Share on other sites
JamesC-120 204 #4 Posted July 7, 2014 This is what I am afraid of is that it is going to need boring, valves ground, crank ground down new piston and rings. If this were a single cylinder I would just rebuild it, but it is 2 cylinder so twice the money to do it. Do you usually replace your pistons with genuine onan pistons or aftermarket? Share this post Link to post Share on other sites
Desko 624 #5 Posted July 7, 2014 I've rebuilt one I miced the bore and was with in spec of STD bore so all I did was buy new rings. Have the bores and crank miced to see if they are with in spec then go from there but if it was taken care of the crank should be fine and I the bores should check out ok but check everything be for you start buying parts. Also the valves should just need lapped in and reseated. IMHO I'd buy OEM because the price is about the same as aftermarket. By no means an I an engine expert though take it to a machine shop for thing that can't be done at home. Share this post Link to post Share on other sites
