60 HP Johnson - 2800 rpm???

[Bassgod]

I have a guy who wants me to work on his older model 60 HP Johnson. I am guessing mid-80's model. He tells me that when accelerating to wot he cannot get the rpm's above 2800 rpm, at that point the motor will shake and sputter terriblly. After 30 minutes or so it will run fine.
Where do I start on this? High speed stator, high speed jets in carbs? Power pack problem? Fuel oil mixture to rich and fouling a plug?
Thanks,
BG

 

[reeldutch]

Re: 60 HP Johnson - 2800 rpm???

start at the beginning,

compresion?
spark?
fuel?
timing?

 

[tashasdaddy]

Re: 60 HP Johnson - 2800 rpm???

i'd take an induction timing light out in the boat and check spark on all cylinders. after following Dutch's advice.

 

[rickdb1boat]

Re: 60 HP Johnson - 2800 rpm???

Correct plugs..Champion QL77JC4 gapped at .040
Thermostat good (closing) and in place..
50:1 mix...
Correct Starting procedure...
Manual valve on primer selonoid in correct position......