1991 Evinrude 25hp....low RPMs?

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boatlose

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My outboard seems like it's running good, but my tach is telling a different story.

Does a 15' welded gregor semi-v tin loaded with 850ish lbs of people and stuff doing 24mph (fishfinder GPS) @ 2800 RPM sound right at all? Idle is around 600-700 according to the tach. No hiccups at WOT. The boat is pretty decently loaded up for sure, but it couldn't be THAT over-propped right?
 
Seems good enough, was just curious if there might be more to get out of it. Just seemed odd to get those low readings when the idle speed readings looked fine. I highly doubt it would go that fast + that load at that RPM!

Maybe I'll order another tach.
 
Where I was going is most of those tachs have different settings for different numbers of cylinders. Might skew the reading.


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2800 be about half speed for that motor. I doubt it would even plane that boat with that load at those rpms.


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Sounds like the tach is reading half of what it should.. weird that idle reading sounds about right.

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GYPSY400 said:
Sounds like the tach is reading half of what it should.. weird that idle reading sounds about right.

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Click to expand...

I agree, sounds like its set on the 4-stroke setting. That would put you at 5600 rpms WOT. However, that would also mean being at 1200-1400 at idle, which surely would be noticeable to you that it's idling really high.
 
For whatever it is worth, I had a similar 15' side console with a 25 hp (4-stroke). Top speed on a perfect day was 27 mph. 25 was more realistic. Like others, I would suspect the tach.
 
I have a very similar setup, only a Mercury 25 and it's from 1995. My boat is a 14' Starcraft deep V with a flat floor. Your speeds are pretty consistent to mine. I'd get 28mph with just me on board. Add another person and some gear and I'd go 24mph.
 
I do not believe you are going to get 24mph at 2800 rpm with a 25hp 2-stroke motor. Look at the back of the tach and see if the setting needs to be changed.
 

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