Optimal RPM range for Yamaha 30 HP 2 stroke

[Tiller guy]

I don't use a tach, but based on my speed and prop pitch it's around 5700 rpm at wot http://continuouswave.com/cgi-bin/propcalc.pl/

[DuckLn]

Those yamahas have an anti rev in neutral mechanism. You can still "give her half throttle and choke it" to start it though.

[DRAGRACR]

Alright, finally got the boat back on the water to check the RPM's again. Something just doesn't seem right though. With the TT set at 3p1r as Bill suggested, my RPM's range from 400(idle) to 3200(WOT). With the TT set at 2p1r, RPM's are running 600-4800. Even at the 2p1r setting, that seems low and the 3p1r setting is REALLY low. I know it's not overpropped. If anything, the prop on it now is pretty worn and a little chewed on the edges--not enough to create increased drag on the RPM's though. Now what? I'd take it to a Certified Yamaha mech to have them check it but I don't have one within 100 mi.

Do yourself a favor and spend the money on a Yamaha tach and problem solved...... I went thru the same crap on 2 3cyl motors before listening to someones advice. For what you are about to spend on a mechanic you can have an accurate tach made for your engine...... Like I said I have 2 of the tiny tachs laying in my tool box....

[Mallards Only]

I don't use a tach, but based on my speed and prop pitch it's around 5700 rpm at wot http://continuouswave.com/cgi-bin/propcalc.pl/

What are you using for the lower unit Ratio in that calculation?

[Mallards Only]

Do yourself a favor and spend the money on a Yamaha tach and problem solved...... I went thru the same crap on 2 3cyl motors before listening to someones advice. For what you are about to spend on a mechanic you can have an accurate tach made for your engine...... Like I said I have 2 of the tiny tachs laying in my tool box....

Really? Hate to spend $300 for a tach. Wanted something small like the TT as well. Does Yamaha make a small digital tach similar in size to the TT? What's different about the Yamaha tachs?

[DRAGRACR]

http://www.ebay.com/itm/NEW-YAMAHA-A...cd5cbc&vxp=mtr

New analog for $114
Used analog for $39
http://www.ebay.com/itm/USED-YAMAHA-...39a527&vxp=mtr

Yamaha tachs are hooked directly to the motor via harness and are triggered by cdi box and not the outside of a plug wire.

[Mallards Only]

http://www.ebay.com/itm/NEW-YAMAHA-A...cd5cbc&vxp=mtr

New analog for $114
Used analog for $39
http://www.ebay.com/itm/USED-YAMAHA-...39a527&vxp=mtr

Yamaha tachs are hooked directly to the motor via harness and are triggered by cdi box and not the outside of a plug wire.

Thanks. Been searching for something smaller that I can mount inconspicuously. I don't really have a good place to mount a large analog tach like that as I stripped the boat of all the internals. Mounting a large analog like that would get torn off instantly in a duck boat by dogs, decoys, etc. Have you ever seen something smaller that could be mounted on the transom or cowling similar to the TT?

[Tiller guy]

Our motors have a 1.85.1 gear ratio. I use 6% slip when working with the numbers. I know it's not perfect, but it worked great for propping my boat and it gives me a ballpark RPM average. If I had the money for some different props and a jackplate then I would definitely buy a good tach.