1990 Johnson vro compression probs

[thebulldog]

I have a 1990 Johnson 60 hp VRO outboard that gives compressions of 100 on 1st, 0 on 2nd, 100 3rd.
ok heres what has been looked into, the centre piston will travel up/down when I turn the flywheel by hand and insert a dowel I can feel the travel, I have removed the centre carb to view the reed valves, they are nice clean and bright and do open/close while turning the flywheel by hand, also all sparkplugs are looking good, no burn indication on any.

Any one have an educated mechanical guess as to the problem ?
The next round is on me, Thank you & Bottoms up !

 

[AEROCOOK]

Re: 1990 Johnson vro compression probs

Hole in your piston or a bad head gasket, preferably the latter.
Either way, you have to remove the head and take a look at what you have... 10 to 15 minutes work at best.

 

[rude1]

Re: 1990 Johnson vro compression probs

The 60 and 70 hp from '89 to '92 ( they changed carbs in mid stream in 92) had problems w/the middle cylinder running hot. there are several service bulletins on these engines. The telltale needs relocating to top of head, the thermostat and sensor need upgrading. The carbs need rejetting. and the wot timing backed to 17deg. If you don't know if yours had these done and if your head is not blown(or if you get it fixed) you may want to check into these. I know because I did these to mine. There should be plenty of info in this forum about the S.B.'s