need to replace control cable for transmission

Apr 27, 2011
423
S2 9.2A Newport News, VA
See if this makes sense: If the lower top RPM situation in forward gear is the prop's fault, then could I advance the speed control until it hits that max RPM, observe the speed control lever's position on the engine and, if it's not fully advanced, and further advancement doesn't change the RPM, conclude that either it's too much prop or the engine is down on power from factory specs? Either way, I guess I should somehow mark the control lever's position so I don't feed it more fuel than it can handle, if that makes sense in Dieselandia. It did seem to smoke more than I would expect at full throttle (more than with the old prop, but the engine wasn't fully warmed, either), although I can't remember if that was only in forward. Probably. Even at 2500 RPM, I saw 7.3 knots over water the last time the boat was out, so it's still pushing the boat pretty well.
 
Oct 29, 2016
1,915
Hunter 41 DS Port Huron
Kazaki Trans S2 9.2A.JPG

I believe this should be your transmission, note the differential between the forward and reverse ratio's
approximately 23% or 13% differential between forward and reverse, you reported a 21% differential between the RPM's which leads me to believe it is likely you have a ratio of 2.33:1 in forward.
 
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Oct 29, 2016
1,915
Hunter 41 DS Port Huron
The issue with being over propped is you are loading the engines torque output in the wrong part of the power curve. I believe your motor reaches maximum output at 3800 RPM, the prop you have on right now is demanding max torque at 2700 RPM's the motor is really not designed to provide the HP at this RPM, I would say that you can't get any further RPM as you are maxed out for HP at 2700 RPM if all that makes sense.
 

jviss

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Feb 5, 2004
6,745
Tartan 3800 20 Westport, MA
I'm getting the impression that there's nothing wrong with your linkage, you just have the wrong pitch Flex-O-Fold. You should contact them.
 
Apr 27, 2011
423
S2 9.2A Newport News, VA
I'll check the specs on the tranny tomorrow. I do know the engine's plate says 16 HP @3400. I'm sure you're right - and I totally forgot - about reverse being a lower gear and thus one that, I assume, lets the engine reach it's rated RPM more easily. Again, pointing to too big a prop, darn it. Time for a turbocharger!
 
Apr 27, 2011
423
S2 9.2A Newport News, VA
I'm getting the impression that there's nothing wrong with your linkage, you just have the wrong pitch Flex-O-Fold. You should contact them.
I will do that. I suppose it's ironic that I had it Propspeed treated.
 
Last edited:
Apr 27, 2011
423
S2 9.2A Newport News, VA
It's a coating you put on running gear - props, mostly - to keep them from fouling. I'm not sure they'll let me post a link here. I'll try: http://propspeed.com/
It's generally recommended that you have it professionally applied, but some folks DIY it. Haven't had it in the water long enough to say if it's helped me any.
 
Apr 27, 2011
423
S2 9.2A Newport News, VA
Checked the transmission. It's a Kanzaki KM2P-1, forward ratio, 2.62, reverse, 3.06. The good news is I got the boat out yesterday for several hours, thoroughly warmed up everything, and saw over 3K RPM in forward. I've not calibrated the tach in a while, but I think that's pretty accurate. At about 3100, it pushed the boat at 6 knots into a 12 knot headwind, so no complaints there. I do think the old cable was holding me back previously, and then I was seeing the low max speed at the dock, which isn't the best measurement. Boy, am I relieved that I don't have to ask Flex-o-Fold to do something about a prop I bought more than two years ago, but only installed this season. Don't know why I posted the stock transmission photo. I guess I just think it's pretty!

Thanks to all.

John
 

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