# sharpening impeller on new motor



## blazer02 (Jun 4, 2015)

I have a brand new mega 25 tohatsu i just picked up other day and i have about a hour of run time on it.i got to looking at the lower unit after i took out other day and i noticed the impeller doesn't come with much of a leading edge to it.the motor flat scoots my 18 48 blazer gpsed it making about 35mph down river.i was wondering if a small sharping job would get me a little more as my old motor always gained a solid mph outta a fresh sharpening.its a aluminum impeller so a no it wont hold a sharp edge after a little bit of run time but i have a score to settle with a old buddy of mine on the river and i was wondering if a sharpening and polishing on the impeller and liner and a little grate work would be worth the effort to gain a mpg or two.he running same motor except i have power trim but he is in a 2ft shorter boat thats lighter.i can get him a half a boat length on holeshot but then he drives around me and puts about 2-3 boat lengths on me and stays there.with my trim and can start reeling him in a little on a long straight stretch but i when we make a bend then and gotta get out of them a bit he pulls back out on me.i not looking to outrun him every time but one good trip a doing it would be great.appreciate any thoughts or ideas.here a few pics of what impeller looks like


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## dhoganjr (Jun 4, 2015)

Need Little Blue Rude to chime in. 

I would sharpen top edge of impeller, sharpen top and bottom of grates (not too much), and polishing impeller will help (too much work for me).

I don't take much off the grates, some guys make a tear drop shape, but for me it seemed to get more rocks and chunks of wood lodged in them.


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## BigTerp (Jun 5, 2015)

Curious about the grate sharpening. How many of you guys do it? Does it make any difference?


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## JoshKeller (Jun 5, 2015)

did it when i redid my grate after hitting a rock. didnt notice anymore speed. did cut my hand the first time i went to clear out some helicopters


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## Lil' Blue Rude (Jun 5, 2015)

You can sharpen on the top side of the impeller and taper the leading edge back so it's a smooth transition from were you sharpened back to the blade. Sharpening the grates might gain a little but you'd be better off to spend that time cutting your liner. When you put your shoe on and look at the liner you'll see the edge of the impeller doesn't meet the leading edge of the liner, you can bevel that edge so it does meet the impeller to help water flow. Stainless 3 blades worth 1mph. You can clean up the inside of the shoe too. Make everything even and smooth flowing. For top end speed try to keep your weight towards the back of the boat, don't move enough that you ride heavy in the back and don't plane properly. On my 16' 42 I figure it up and 75lbs in the front of the boat is the same as having around 300lbs in the back of the boat by the time you figure up the leverage and the center of gravity of my boat.


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## BigTerp (Jun 5, 2015)

JoshKeller said:


> did it when i redid my grate after hitting a rock. didnt notice anymore speed. did cut my hand the first time i went to clear out some helicopters



HA!! Did you sharpen the grates so much you could shave with them?


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## RiverBottomOutdoors (Jun 5, 2015)

Sharpened my grates. Didn't do jack.


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## BigTerp (Jun 5, 2015)

RiverBottomOutdoors said:


> Sharpened my grates. Didn't do jack.



That seems to be the consensus. 

I need to change my water pump impeller before hunting season. While I have it apart I will probably clean up and polish my impeller and try to clean up/polish my pump. Not sure how much cleaning/polishing the pump will do though?


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## JoshKeller (Jun 5, 2015)

BigTerp said:


> JoshKeller said:
> 
> 
> > did it when i redid my grate after hitting a rock. didnt notice anymore speed. did cut my hand the first time i went to clear out some helicopters
> ...



nope just put a edge on both sides - it was early and i was still half asleep and wanted to get to a spot before anyone else so instead of using my brush, i just ran my hand back to clear them off.. felt a grab and looked down and my hand was sliced open.


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## rktman (Jun 9, 2015)

blazer02 said:


> I have a brand new mega 25 tohatsu i just picked up other day and i have about a hour of run time on it.i got to looking at the lower unit after i took out other day and i noticed the impeller doesn't come with much of a leading edge to it.the motor flat scoots my 18 48 blazer gpsed it making about 35mph down river.i was wondering if a small sharping job would get me a little more as my old motor always gained a solid mph outta a fresh sharpening.its a aluminum impeller so a no it wont hold a sharp edge after a little bit of run time but i have a score to settle with a old buddy of mine on the river and i was wondering if a sharpening and polishing on the impeller and liner and a little grate work would be worth the effort to gain a mpg or two.he running same motor except i have power trim but he is in a 2ft shorter boat thats lighter.i can get him a half a boat length on holeshot but then he drives around me and puts about 2-3 boat lengths on me and stays there.with my trim and can start reeling him in a little on a long straight stretch but i when we make a bend then and gotta get out of them a bit he pulls back out on me.i not looking to outrun him every time but one good trip a doing it would be great.appreciate any thoughts or ideas.here a few pics of what impeller looks like.



Holy schmolly, how do you get 35 mph out of a Tohatsu 40/25 with a .100 gauge 18x48 Blazer?


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## blazer02 (Jun 29, 2015)

rktman said:


> blazer02 said:
> 
> 
> > I have a brand new mega 25 tohatsu i just picked up other day and i have about a hour of run time on it.i got to looking at the lower unit after i took out other day and i noticed the impeller doesn't come with much of a leading edge to it.the motor flat scoots my 18 48 blazer gpsed it making about 35mph down river.i was wondering if a small sharping job would get me a little more as my old motor always gained a solid mph outta a fresh sharpening.its a aluminum impeller so a no it wont hold a sharp edge after a little bit of run time but i have a score to settle with a old buddy of mine on the river and i was wondering if a sharpening and polishing on the impeller and liner and a little grate work would be worth the effort to gain a mpg or two.he running same motor except i have power trim but he is in a 2ft shorter boat thats lighter.i can get him a half a boat length on holeshot but then he drives around me and puts about 2-3 boat lengths on me and stays there.with my trim and can start reeling him in a little on a long straight stretch but i when we make a bend then and gotta get out of them a bit he pulls back out on me.i not looking to outrun him every time but one good trip a doing it would be great.appreciate any thoughts or ideas.here a few pics of what impeller looks like.
> ...







The 35 is down river with just me in boat and with motor trimmed out 
As perfect as u can get it.these motors are actually very powerful for there size and with the direct injection and still being 2 stroke they wind up fast and hard.


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