85HP Rebuilt Can't get to run right

[Chucky P]

I have a 76-77 85hp Merc.Electronic Ig. I lost #4 piston & rings & lower bearing. I had #4 bored 30 and replaced upper & lower bearings. Reeds all look good & gaps were all correct. Boat rain at 35mph + before.(Tach.not working) Motor started in tank & ran good.Took it out to put breakin time on it,(I'm running 25/1 oil for breakin) Motor seemed very weak! Didn't push it but tried to run speed up & it would barely reach 20mph very weak! I thought it might be spark advance and carb linkage needed to be adj. Took it to a Boat Mech. to set this all. Went back to talk to him today & he said when he set everything, it wouldn't run at all. I had a leak in gasket at bottom of 4 inch spacer under powerhead. Took it home & fixed this. Can anyone think of anything I missed? The Mech.said to bring it back after I fixed gasget,and he would try again. Thank You all Chuck

 

[hondon]

Re: 85HP Rebuilt Can't get to run right

Why did you "lose" # 4 to begin with? That might be what you are overlooking and it has happened again.Recircs are often overlooked when rebuilding these engines.Did a ring get broken on installation?It happens easy enough.When that machine shop did the bore it is possible that with a unit of this age it generated enough friction to loosen the sleeve in that bore and it has now slipped loose.Seen that before.What did that shop say your compression or leakdown values were?

 

[Chucky P]

Re: 85HP Rebuilt Can't get to run right

Thanks,#4cyl.spark plug left out all winter. I sure water got into Cyl.Machine shop all looked good,and he had specs. for new piston. I checked ring play through side as it said in book.I put a new pickup on when I had flywheel off.It was a little diferant but linkage lined up and wires were all right colors.This is the only different elec.part changed. ??? Thanks again Chuck