I have a 92 sp with the white 580 rotax. I went to start it up for the first time this year and didn't realize that the oil line to the carb had degraded and broke. Both the return and the oil line to the crank were alright. It started up at the house almost immediately and ran for about 3 seconds before I shut if off to take to the lake. When I got to the lake I cranked it for about a minute and it wouldn't start. Then there was a loud backfire that was powerful enough I could feel the Shockwave from it. When I got it home I realized the oil line was broken and thought to check compression. Both cylinders were coming back around 45-50 psi. I pulled the head expecting the inside of the cylinder walls to be destroyed but they both looked perfectly fine with no groves or gouges. For a reading as low as 45 psi, I expected something visible. That made me think more looking for a gasket somewhere that had blown but the head gasket looked alright. Is there another gasket I could check/ any other suggestions for why compression would be that low?
92 580 loud backfire then low compression
- Thread starter bowenlhzn
- Start date
I think when you get the grooves of where you have a catastrophic failure suck as a piston skirt breaking or a ring breaking and getting caught up in there or if aomethin got dropped in the crank and made its way up into the combustion chamber, what you have is some good ole wear due to lack of oil , I’m sure if you take some measurements you will find it’s worn enough to give you the bad compression, however it is worth trying a different gauge.
