Getting the most of my motor

[mtspro6]

It seems to me that the dealers are propping the new Mercury motors (75-115hp) the same as the older veradita motors. The gear ratio is different on the new motors and they simply will not spin the rpm that the older motors will with the same prop. Mercury bulletin shows that my particular boat is slower (14 impact) with the new motor as compared to the older one. Good luck getting it sorted out. The 17 pitch will probably work much better.

[yamaha1973]

It sounds like you may have a couple things going on. Too much prop and possibly a tach that isn't reading correctly.

[Rock Lobstar1]

What's the easiest way to test the tach?


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[egladding]

First off with the tach issue, can you hear any difference in RPM from 3/4 to full? If you can't hear a difference by ear then it's probably accurate. If there is a noticeable difference by ear then the tach is definitely not reading accurately.

[Rock Lobstar1]

Definitely no audible increase in rpm.

[egladding]

Then your tach is probably fine. I would have the dealer check your throttle linkage first. You should hear a difference in your motor form 3/4 to full. Sounds like you aren't getting full WOT out of your motor.

[Rock Lobstar1]

Update. Dealer looked at it and says it's getting full range of motion on the throttle linkage. Took it on the water with them and concluded its most likely the prop. It seems as though it's just running out of steam on the top end. Kind of a bummer. I'm gonna order a 17p prop since I wanted to have a spare anyway. I'll update again once the prop is replaced.

[bigwillies]

brother in law has the identical rig.says he has the 4 blade 17 pitch.43 byhimself and the top down.39 with the wife and the top up. good holeshot too

[jimmythegreek]

thats not a very heavy boat overall and a 4 blade is not the best for top speed. Figure out what you want whether its holeshot and low speed handling or less holeshot and better top end. If you switch to a stainless you could raise motor a hole or two and have the best of both worlds. It is strange that you hear no difference in the rpms in relation to the engine noise, Im guessing the 17P wont be low enough to get your rpms up to 5500 or higher

[Rock Lobstar1]

I'm actually happy with the holeshot as it is and not really looking for anymore top speed. The lakes around here in northwest Ontario have way too many hidden rocks and reefs, so 40mph is more than fast enough for me. And I certainly don't cruise around WOT all the time. But it would be nice to be able to utilize that little bit extra jam if needed. I almost feel a bit jipped. Even if I never went past 3/4 throttle ever again it would be nice to know it would do something when I do.
I'll post pics below of throttle positions when I can max it out at 5k rpm and full throttle.
https://images.tapatalk-cdn.com/15/06...68fbe45878.jpghttps://images.tapatalk-cdn.com/15/06...5ba8fe920d.jpg
Maybe it's a bit more that 3/4 throttle. I didn't bring the protractor out haha.


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