Bad Tach?

[Matchrocket]

I have already searched the forums for my issue and I didn't find it. I suspect that my tack is reading wrong. I checked to make sure it was set correctly and I believe it is. I have a 95 Merc 115 HP 4-cyl 2-Stroke outboard and the setting should be at 6P, correct? The max cursing RPM for this boat should be ~5300 RPM. Yet when I am running at 5000 I am only going about 25MPH @just over 1/2 throttle. The motor doesn't sound like it is even turning that fast. I have a 13 X 19 prop on it. Out of the water the tachometer says I am idling @ just under 2K RPM. But it really doesn't sound that way. I have only hit WOT once and I was just over 6K. I didn't like that much so I backed out. I am not the first owner of this boat. Any help would be greatly appreciated.

 

[rickdb1boat]

Re: Bad Tach?

Maybe I missed it, but what Brand is your Motor?

 

[495v]

Re: Bad Tach?

First off, your idle RPM should only be around 800-1000. Does your gauge have a calibration screw on the back end? I would recommend hooking up an external meter to check and be sure. Try calibrating the gauge to the meter. FYI, the screw does not stick out at all. There is usually a little hole on the back, with a screw buried in it.

 

[rickdb1boat]

Re: Bad Tach?

Ok, I re-read it! Yes, Merc 115 should be set on 6 pole!

 

[Matchrocket]

Re: Bad Tach?

Is that in or out of the water?

 

[rickdb1boat]

Re: Bad Tach?

That's in Neutral. But it does'nt matter, just as long as you sync it with another tach!

 

[Matchrocket]

Re: Bad Tach?

I had the local shop compair my tack with the shop tach while it was being winterized. Mine was off by just over 1500 RPM. It was set to the correct pole setting. They could not get it adjusted right so they replaced it. It works just find now.

 

[495v]

Re: Bad Tach?

Good deal! But why are you winterizing the boat so soon?