Merc. 1974 85hp serial Nr.3871943 looking for some input????

[Gomer50]

I was given a 85hp motor that hasnt run in 5 or 6 years.She spins freely with no plugs in it,but when I put the compression tester on the number 1 plug she has a hard time cranking over.I have put oil in the cylinders spun them around with no spark plugs and she spins like crazy.I put the compression tester on the 2,3,4, it barley cranks over but I am showing between 150 and 140 psi. I spray oil in the number 1 cylinder and test she will show 150 then drop to 120 and sometimes will only show 100 psi.Battery is good maybe the starter isnt in the best of condition anymore.This test is done using jumper cables directly to the starter from the battery.I have also put seafoam in each cylinder and will let soak overnight see if this changes.My question is it possible the starter doesnt have enough umph to crank her over good,or might there be something else?
Thanks guy's......

 

[Barnacle_Bill]

Re: Merc. 1974 85hp serial Nr.3871943 looking for some input????

Yes the starter could be corroded up inside. Also here is a good read for you. http://forums.iboats.com/showthread.php?t=158086

 

[Gomer50]

Re: Merc. 1974 85hp serial Nr.3871943 looking for some input????

Thanks,I have a newer starter off of an 80 hp and will check to see if things change.Sure would be nice to have good compression all the way down.Maybe this year the boating experience will be more enjoyable.My 80hp was nothing but a pain in the you know what.

 

[Gomer50]

Re: Merc. 1974 85hp serial Nr.3871943 looking for some input????

Okay gentlemen,I let this motor sit overnight with 2 cycle oil and some seafoam.Now is there such thing as to much compression??I ran the compression with all the plugs out except the cylinder I was checking with the guage and each cylinder is way over 160 psi.If I put in all the spark plugs and try to crank her over,she will barley turn over.This is done with a good battery and heavy duty jumper cables directly to the starter,also I fairly new starter that worked great on a 80hp motor.Any Ideas why its so hard to crank her over with the spark plugs installed??
Thanks..