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Discussion Starter · #1 ·
Hi all,

Last year I replaced my old 2-stroke 4hp Merc kicker with a newer 4-stroke 6hp Tohatsu. The Tohatsu was used as a main for a drift boat and the previous owner installed a high thrust prop for a bit of extra oomph. For my application, using it as a trolling motor on a relatively light 16' Lund, the high thrust prop doesn't seem like the best fit. In most situations when I'm not fighting a decent amount of up river current, I struggle to find a comfortable rev range for the motor. In calm conditions, it is practically idling in gear to give me the trolling speeds I need. This makes for a bit of vibration and causes the motor to hunt around the lower rev range.

All that said, I am looking to swap the prop out for something a bit less aggressive so I can use the motor in a more comfortable and smoother rev range. Any suggestions on where I might be able to find a prop suitable for my application?

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Thanks!
 

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The “high thrust” prop IS typically what you want for trolling… it’s usually the lower pitch prop which is what you want.

Is that the MFS6D (one cylinder) or MFS6BZ (2 cylinder)? If it’s the 6D which it looks like, you can expect a lot more vibration than you’re used to because of the single cylinder.

Either way, look for the lowest pitch prop you can get for best trolling range.
 

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Discussion Starter · #4 ·
What size is the prop on it now?
I am unsure, as the previous owner didn't provide me with any sizing info. I haven't messed with props before though, so is there anywhere on the prop itself that might list that info?

The “high thrust” prop IS typically what you want for trolling… it’s usually the lower pitch prop which is what you want.

Is that the MFS6D (one cylinder) or MFS6BZ (2 cylinder)? If it’s the 6D which it looks like, you can expect a lot more vibration than you’re used to because of the single cylinder.

Either way, look for the lowest pitch prop you can get for best trolling range.
This is the MFS6D 1 cyl model. I understand it will have more vibrations compared to a 2 cyl but at near-idle RPMs it is significantly less smooth compared to giving it 10-15% throttle. My idea is to get a less aggressive prop to be able to run the motor at slightly higher RPMs.
 

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You have the lowest pitch prop already. It's the high thrust or sail prop 6" pitch.
There is a standard 6" prop also available, it will help reduce vibration a bit as well, but the prop is 100$ I see em on eBay often.

I have over 400 hours on mine in the two years I habe it. Love hate thing with this motor but it brought us in 7 miles last year when my main quit.

Vibration wise, put a digital tach on it. At idle and in gear you are probably running 1300 rpm, that is Factory spec.
With warm engine you can adjust it to 1100 it will reduce vibration quite a bit. Screw on the carb for it.
Off idle at 1500 rpm and up it will shake, no way around it. Nature of this motor.

I also have mine mounted on rubber mud flap between motor and transom, big difference in reduced vibes.
I also added foam to inside of cowel much quieter too.
Also drilled out the third exhaust port hole so it breaths a bit easier at idle.

Lots of small things to do to reduce vibration. To eliminate it, put a rope in it and anchor it. With that said I love mine.
 

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I am unsure, as the previous owner didn't provide me with any sizing info. I haven't messed with props before though, so is there anywhere on the prop itself that might list that info?



This is the MFS6D 1 cyl model. I understand it will have more vibrations compared to a 2 cyl but at near-idle RPMs it is significantly less smooth compared to giving it 10-15% throttle. My idea is to get a less aggressive prop to be able to run the motor at slightly higher RPMs.
I’d take it down to AMPRO in Clackmas and talk to them. Those guys will fix you up with what you need and let you return it and try something else if it’s not banged up. Kirk
 
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