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#1
04-29-2014, 01:28 PM
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Prop question on 25 4stroke tohatsu
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#3
04-29-2014, 02:29 PM
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A 25hp motor will not turn a 15 pitch prop of any brand. You will not get the best of, top end speed, great hole shot, and good mid range, unless you add 50hp to the motor.
Under the best of circumstances, a 25hp 4 stroke will turn a 12 pitch prop with no added cup on a boat with no tunnel. When you start adding cup, which you will need to do to prevent cavitation on a tunnel, you raise the average pitch. My guess is that you will end up with about a 10 pitch prop with added cup for the tunnel. Your top end will be somewhere in the low 20's. That is after you deduct the 5mph that a tunnel cost any boat. D
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#4
04-29-2014, 03:27 PM
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I have a 25hp turning a 18 pitch
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#5
04-29-2014, 04:33 PM
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Quote:
Thread Title:"Prop question on 25 4stroke tohatsu"
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#6
04-29-2014, 04:34 PM
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It is a 2 stroke merc
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#7
04-29-2014, 05:24 PM
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I was watching knee riders racing 25XS mercs before you were born
 But they could only turn 8-10" pitch props, on a speedmaster gear case.
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#8
04-29-2014, 07:01 PM
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uploadfromtaptalk1398815915867.jpg I know a little about old mercs and I promise my my 25 is turning a 18 pitch chopper this is my old 25ss its only turning a 14 pitch
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#9
04-29-2014, 07:05 PM
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I don't know the diameter of prop you are referring to but you just said no 25hp was gonna a 15 pitch. There is always an exception
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#10
04-29-2014, 07:07 PM
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And you were most likely just meaning 4 stroke.
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#11
04-29-2014, 07:48 PM
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Thanks Cajun I figured that 15 would be to much for my motor and it's hard to find someone with the same setup. What prop do you suggest and the boat is the marsh runner edition from lake area if that helps any
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#12
04-30-2014, 07:08 AM
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Most of those motors turn An 11 or 12 pitch prop, not on a tunnel. Tach the motor with that solas on it then, call powertech with your info. Bear, Your little boat is neat, but since the thread title was 4 stroke 25 tohatsu, that's kinda what and who I was talking to.
I think it's great that we have grass roots racing, it has spawned many Professional Racing careers. I raced Professionally for 10 years, from Mexico to Canada, from California to the East Coast, there isn't much you will impress me with. Local racing is great, go pro and stack up against the factories, that will show you where your program is.
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#13
04-30-2014, 07:56 AM
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Bear, to give you an idea of the professional circuit:
The Mod C Kilo record is 99 mph. Mod C is a modified motor of 30 cubic inches or less, minimum weight of 600 pounds after the run, fuel must be liquid. That's 99 mph with no nos, all motor. Record was set back in late 90's with a 3 cylinder Yamaha 25hp motor. Again, it is a "MOD" C, highly modified motor. First Class I ran was Sport C. A STOCK motor of 30 cubic inches or less, BOX STOCK, no nosecone, no mods. I ran a 2 cylinder, single carb, Tohatsu 40hp twin. Set up for a long circle race, the boat would run 60mph down the straightaways. Yep, those old junky 2 cylinder Tohatsu's would turn 18 pitch cleavers 7200 rpm. The KILO record for a STOCK 50hp Tohatsu is 82.7 mph. That's 7400 rpm with a 12" diameter 24 pitch cleaver. Ask some of your buddies, I played with them back in the 80's, like Hank....great guy, Duane, the Borels, all great people. Listen to Hank, that guy is smarter than most people think he is. I never met a guy on the Sabine I didn't like. We could get out there and race then go to the bank and remain friends. Great bunch of folks. Jerry has a knee rider in his attic. It is a 7' boat running mid 80's with JERRY in it, with a 25 merc on it. It is the "stop the BS" boat. Darrel knows more about mod motors than most people will ever know. I have the utmost respect for those guys. They are the tinkerers, the ditch racers, the folks that experiment with stuff that becomes production. I have respect for the ditch racers, and I call them that as a compliment. The ditch racers do their thing with very little safety equipment, it takes guts. Racing professional, we had capsules, Kevlar vests, helmets, safety crews. Our APBA sponsored racing was 100 times safer than ditch racers. Ditch racers are the blue collar segment of boat racing. They deserve much more credit than they are given.
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#14
04-30-2014, 08:21 AM
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The more you talk, the more it sounds like you have an AlWeld "performance" tunnel??????
D
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#16
04-30-2014, 12:01 PM
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Hey CajunC its all good, you know way more than me about all of this racing stuff. I just was giving my 2 cents about the no 25hp turning 15 pitch prop. I was out of place because I was referring to modded 2 stroke motors and you are referring to stock 4 strokes. Its all good though. I still have lots to learn and im all ears if you ever want to talk about racing. I got all my race stuff from Rayburn Davis, you may have heard the name. His setup was suppose to be mid 60s on the 10ft boat pictured. I've yet to hit those numbers but ill get there.
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#18
05-01-2014, 10:41 AM
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My cousin gave me a solas B10x11 3 blade and it's a little rough on the edges but I'm bringing it to precision props off hwy 14 and he said 50$ and he'll re pitch it for me. But what y'all think about adding a little more cup to it? I know a little goes a long way so just want y'all's opinion
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