Tachometer for tiller 50hp 4 stroke

[greginwisc]

Hi all. I was wondering if you could help me out. I would like to put a tach on a 2006 50hp 4 stroke TILLER. I just want the engine rpm, no warning lights, trim, ect (but if is included that's ok). Is there a harness that I can get to hook this up. Yamaha part #s for a harness and tach would be great too if this is possible.

Mostly I need to get the prop set up. Right now I'm running a 15 pitch and I think I'm over prop'd.

Thanks for taken the time.

-greg

[greginwisc]

anyone have any ideas?

[NMG]

Not sure about the tach greginwisc, but I agree that you may be over propped. I'm running a 12 pitch on my 50 4 Stroke and it tops out at around 5,800 RPM and 31 MPH in ideal conditions. This is on a 16 foot aluminum hull. The 12 is nice as it will plane 3 adults no problem and still run high 20's. It doesn't really lose much with larger loads, just a little slower to get on plane.

I also have a 13 pitch and it will get 5,600 RPM in ideal conditions and it will run around 33 MPH at those RPM's but it's a little slower out of the hole.

A 15 would certainly be too much for my hull but I totally understand why you would want a tach to confirm. It would be tough to dial everything in without it. I've heard that there are also "portable" tachs that you can buy where you just attach clips to certain wires and it will give you a readout, however, I'm not too certain on where to find them or what applications they work on.

My engine is not a tiller so it came with the Yamaha Multi Function gauge. There has to be a way for you to get some RPM readings. Have you tried your local Yamaha dealer?

You could also try posting on the boats and motors forum at Walleye Central. Here is a link:

http://www.walleyecentral.com/dc/dcb...topics&forum=6

I'd be SHOCKED if you didn't get some more responses over there.

Good luck!

[greginwisc]

Thanks for the info. A friend had an inductive tach and confirmed what I thought. I also have a 16' and we are running nearly identical rpm's. I went with the 13 since I mostly fish alone.

[NMG]

Glad you got it figured out!

[ron7000]

an inductive timing light that gives rpms and hooks onto a spark plug wire is a good way to do it, provided you have one.
But on any 4 stroke engine (and 2-stroke) spark ignition (that's using spark plugs) the way it is shut down is by grounding out the coil. There is a lead off the coil, that runs to the little red pushbutton usually, that you push to kill the motor. This wire, coming off the coil, has a pulse to it and is also the signal wire you can use on a tach. The trick then is dialing in the tach for the correct pulse count. It should be 2-pulse.
I do this on all kinds of small engines- lawnmowers, small blowers, it's all the same principle.
I just went through hooking up an old teleflex tach to my new yam 25hp 2-stroke for the same reason as you. All that took was finding the correct wire hanging off the cdi box though, and I was also able to back up the tach reading with a timing light showing rpms.