1989 50HP, 3 cylinder, Manual on Backorder

[Marc E]

In neutral, 5800 RPM; in gear, 3600 RPM. Squeezed bulb and boat stayed at 4400 RPM (as long as we were pumping in the fuel). Changed the 3 plugs; the bottom plug looked brand new. Took off carbs. noticed the floats are at different heights? If you have a manual for this motor; please you tell me the correct height of the floats. Where do I start and are any of these topics related? Thanks in advance for the help.

 

[ricksrster]

Re: 1989 50HP, 3 cylinder, Manual on Backorder

From the base of the carb to bottom of the float while it is resting on the inlet needle is 11/16" (17.46mm).

 

[Marc E]

Re: 1989 50HP, 3 cylinder, Manual on Backorder

Thanks for the float height, and I am headed to the garage right now!

 

[AMD Rules]

Re: 1989 50HP, 3 cylinder, Manual on Backorder

I hope those rpm numbers you posted are incorrect. You'll be rebuilding the motor shortly if you are actually running it at 5800 rpm in neutral.

Never run your motor above 1500 to 1800 rpm in neutral. 2-strokes have a tendancy to take-off on you and the next thing you hear is the clunk/squeel/bang.

That motor should idle at well less than 1000 rpm in neutral on muffs, and down below 800 rpm in gear in the water.

 

[Marc E]

Re: 1989 50HP, 3 cylinder, Manual on Backorder

Assuming my tach is correct; I did throttle up to 5,800 RPM in neutral....I will definitely not do it again. Thanks for the feedback. The motor does idle right at 1,000 RPM when in the water. I did not check on the muffs. What do you believe normal RPMs to be when going down the lake at full throttle? Does the 4,400 RPMs that I posted sound correct? Thanks again.

 

[ricksrster]

Re: 1989 50HP, 3 cylinder, Manual on Backorder

5300 -5800.

 

[Marc E]

Re: 1989 50HP, 3 cylinder, Manual on Backorder

Thanks for all the help Ricksrster! Just got in from the lake and you were bang on about the float height. The boat ran at a constant 4400 RPM and no continual pumping of the tank bulb required. Since my wife tells me that I still don't have the Mercury Manual yet; what's the direct that I need to go to get the motor running at 5300-5800? I don't want to wear out my welcome, but I have learned more from this website in the past 24 hours than other searches. I appreciate any help that you all care to share.

 

[AMD Rules]

Re: 1989 50HP, 3 cylinder, Manual on Backorder

If you're not developing enough rpm it could be due to a few reasons:

- check to make sure the boat isnt water-logged, or carrying excessive weight

- prop may be too big for the motor/boat combination. Might need to srop down a pitch or two.

- check to make sure the both carb throttle plates are fully open when the throttle is moved all the way to wide open throttle.

- double check the timing, to make sure you are at the appropriate amount of spark advance at wide open throttle position to develop max horsepower

- does the motor have good spark on all cylinders

- will it go faster if you have an assistant squeeze the fuel primer bulb when at 4400 rpm

etc...

Thats a start...