Bigprairie1
Commander
- Joined
- Jun 13, 2007
- Messages
- 2,568
Well after a year or so 'off the water' with my 90hp, it looks like we are ready to go again.
Many thanks again to Frank and JerryJ for their excellent tech info on how to change out a piston without a complete engine teardown.
We had the boat out last night for a quick run on a local lake and it ran out really nicely, start and idle through full throttle. The only thing left to do is add a bit more wide open throttle adjustment to the linkage because it sounds like its a few hundred rpm off. This should be a pretty easy shore check and adjustment and I wouldn't be surprised if I didn't set the max throttle up quite properly during re-assembly. I did take the time to set all (3) individual carbs to the same throttle/open plate points tho'....thanks again to Franks video.
I also cleaned the carbs when I had them off and I was really impressed with how smooth it was running. All (3) carbs are set to 1 full adjustment out on the mixture screws to avoid any lean condition.
The previous (pre 'new' piston) compression numbers had shown an internal problem with compression and #2 cylinder (top to bottom) in the range of 115psi / 60psi / 120psi or thereabouts.
Compression now is showing (top to bottom) 115psi / 115-117psi / 118-120psi....so I'm happy with those numbers.
I did a slight hone on the middle cylinder before the piston replacement and made sure I chamfered all the internal ports slightly to 'hopefully' minimize another ring catch.
Costs all in were in the neighbourhood of $300+ to my recollection with the breakdown being: Wiseco piston/ring- $175, head gasket and carb gaskets- $80, new thermostat- $10 or something close to that and 3 new BUHX plugs.
If there is any good follow up advice by all means weigh in guys.
NOW....if I could just get my tach working again LOL. Maybe I'll start another thread on how to troubleshoot that thing.
All Good
BP
Many thanks again to Frank and JerryJ for their excellent tech info on how to change out a piston without a complete engine teardown.
We had the boat out last night for a quick run on a local lake and it ran out really nicely, start and idle through full throttle. The only thing left to do is add a bit more wide open throttle adjustment to the linkage because it sounds like its a few hundred rpm off. This should be a pretty easy shore check and adjustment and I wouldn't be surprised if I didn't set the max throttle up quite properly during re-assembly. I did take the time to set all (3) individual carbs to the same throttle/open plate points tho'....thanks again to Franks video.
I also cleaned the carbs when I had them off and I was really impressed with how smooth it was running. All (3) carbs are set to 1 full adjustment out on the mixture screws to avoid any lean condition.
The previous (pre 'new' piston) compression numbers had shown an internal problem with compression and #2 cylinder (top to bottom) in the range of 115psi / 60psi / 120psi or thereabouts.
Compression now is showing (top to bottom) 115psi / 115-117psi / 118-120psi....so I'm happy with those numbers.
I did a slight hone on the middle cylinder before the piston replacement and made sure I chamfered all the internal ports slightly to 'hopefully' minimize another ring catch.
Costs all in were in the neighbourhood of $300+ to my recollection with the breakdown being: Wiseco piston/ring- $175, head gasket and carb gaskets- $80, new thermostat- $10 or something close to that and 3 new BUHX plugs.
If there is any good follow up advice by all means weigh in guys.
NOW....if I could just get my tach working again LOL. Maybe I'll start another thread on how to troubleshoot that thing.
All Good
BP