2011 60hp mercury bigfoot 4-stroke on a 20' pontoon

[larryrockwes]

The last 2 trips out to the lake I have noticed the the RPM's are runiing about 5400 wide open. And when I would try to raise the trim of the motor it would slow the pontoon way down if the trim was to high it has never done this before is there anything That I can check on the trim to stop it from coming up so high. the boat was running about 6000 Rpm's last year. Where is the relief valve on the power trim? Sorry for so many Questions. Thanks Larry

 

[galamb]

This may sound like an odd question but is it considerably more hot and humid this year when you are only getting 5400 rpms as compared with last year when you were getting 6000.

It is totally "NORMAL" for a motor to lose 10-15% of it's top end in hot/humid weather. The only way to compensate for that is to change props (again, that's what should be done but no dealer will ever tell you that when you buy a new motor).

If a motor is "propped" in the spring or the fall, then a second prop with about 2" less in pitch is required in the height of the summer if all other operating conditions remain the same. Conversely, if the motor is propped in mid-summer, you should shoot for the lowest end of the WOT (wide open throttle) range since your rpms will "naturally" increase in the spring or fall and you don't want to have a condition where you could over-rev (and damage) your motor.

So their may be nothing wrong with your motor at all - it could simply be the weather.

Here's a diagram of the power trim release valve.

 

[papyson]

i am running a 2011 60 big foot also...top rpm dropped 200 rpm with a slight increase in load....one more person plus some gear...i am not worried about it with this 100 degree weather..the 500 rpm between 5500 and 6000 dont buy me anything with my rig anyway...no additional torgue or speed...motor is a perfect match for the boat at 5500 and under...i think the motor is performing as designed...i will add one thing...its a gas hog at 5k rpm or above...it may get a little boring but 4k rpm is a lot better on gas..