1985 Johnson 140 hp

[wheezer2003]

I am a new owner. No manual. What is the rpm redline?

 

[o/b tech]

Re: 1985 Johnson 140 hp

No more than 5800 rpm and anything past 5500 you start falling off the power curve for the motor.

 

[kenmyfam]

Re: 1985 Johnson 140 hp

I thought it was 5,000 to 6,000 ?? in the book with 6,000 being better than "lugging " the motor if nearer the 5,000 mark.
I will stand corrected.

 

[o/b tech]

Re: 1985 Johnson 140 hp

5000 to 5500 is the optimum operating range. If the motor is running up to 6000 rpm than the risk greatly increases that it may suffer mechanical failure as that any ventilation of the prop, at this point, will cause undo stress on the rod bolts. Hope this helps.

 

[wheezer2003]

Re: 1985 Johnson 140 hp

Thanks for the quick reply. One more question. I pulled the prop off to check it. It has a 12 3/4 inch 21 pitch prop on it and I am running it on a boat rated for a 150 hp max, a fish and ski. Will that prop perform well?

 

[ezeke]

Re: 1985 Johnson 140 hp

You should prop the motor to reach 6000 RPM under your personal average load when at WOT.

 

[kenmyfam]

Re: 1985 Johnson 140 hp

You should prop the motor to reach 6000 RPM under your personal average load when at WOT.

I just knew I got 6,000 rpm from somewhere.
Mine is propped for the 6,000 rpm mark. I thought I was doing something wrong there for a while !!!!