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How high will a 49ci motor rev?
https://hpbc.ca/viewtopic.php?f=19&t=3461
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Author:  13Checkmate [ August 4th, 2016, 10:28 am ]
Post subject:  How high will a 49ci motor rev?

Looking at trying to get my delta faster, i can get the motor up another hole and move the setback bracket up another half to 3/4". Right now im revving between 6300-6500 with a 24 raker at 58ish mph, havent hit a limiter. How high will a stock motor rev without pushing its limits? It is an 85 70hp powerhead, with the primer style carbs. Hoping that going higher on the transom puts me in around 6700-7000 rpm with the 24 raker at over 60mph

Author:  phillnjack [ August 4th, 2016, 6:36 pm ]
Post subject:  Re: How high will a 49ci motor rev?

Your talking bollocks.
24 pitch raker means your running 2.42 ratio longshaft motor .
No chance swinging a 13.5 x 24 raker on a shitty old stock 49cu in.
If you do a lot of mods then maybe she will get to 6500 . The later 56 cu in will struggle to.get to 6500 with 24 raker. And they are around 15hp more at the prop. Without mods the 49 cube is 55hp at prop max.the people you see with 49 cu in engines revving high have spent a lot of time and money making them do it.
And they don't get it with 13.5 inch diameter x 24 props..
I bet your motor cannot reach anywhere near 5500 with a 24 raker.

Author:  13Checkmate [ August 4th, 2016, 7:51 pm ]
Post subject:  Re: How high will a 49ci motor rev?

Not running a long shaft, tach says 6300-6500 and sounds like it. Feel free to catch a plane from the UK to watch it go, boat runs 57-58.5mph on gps. Need a pic of the gps'd speed? Got no problem doing that

Author:  phillnjack [ August 4th, 2016, 9:26 pm ]
Post subject:  Re: How high will a 49ci motor rev?

So is this a 1.86 box too

Author:  13Checkmate [ August 4th, 2016, 10:37 pm ]
Post subject:  Re: How high will a 49ci motor rev?

Not yet, 2.42 lower

Author:  phillnjack [ August 5th, 2016, 6:17 am ]
Post subject:  Re: How high will a 49ci motor rev?

Are you using a blue bottle ?.

Can you post a pic of this engine showing both sides of powered and the cylinder head.

Author:  sharpeye Mike [ August 5th, 2016, 8:23 am ]
Post subject:  Re: How high will a 49ci motor rev?

I always ran cleavers with my Delta at a one inch below the transom. 62 MPH is the best I could get with a 75 HP Stinger and nitro gear case, now I changed powerhead to a 56 and I'm at 68 + with the same wheel. I tried setting back the motor a bit and didn't like the way the boat handled waves so it went back on the transom from there.

Author:  jake@elsey.ca [ August 5th, 2016, 8:36 am ]
Post subject:  Re: How high will a 49ci motor rev?

Phillnjack. How many race engines have you built, raced, or tested?

Don't be so quick to bash people on this site please. You don't appear to have any credible experience doing anything with a three cylinder engine. Is your only knowledge of race engines acquired through staying up late reading online forums?

A strong 49 is better than a stock 56, and I have the race footage and experience to back it up, as do many others. A few years ago craig Fraser ran a similar setup too. A stock 49 on a big foot in T750 ran ~58 with zero setup time.

You can't really claim to know anything - so try to be nicer, ya?
The wife should take your keyboard away I think...

Author:  LittleCharger [ August 5th, 2016, 9:28 am ]
Post subject:  Re: How high will a 49ci motor rev?

sharpeye Mike wrote:
I always ran cleavers with my Delta at a one inch below the transom. 62 MPH is the best I could get with a 75 HP Stinger and nitro gear case, now I changed powerhead to a 56 and I'm at 68 + with the same wheel. I tried setting back the motor a bit and didn't like the way the boat handled waves so it went back on the transom from there.


The mph differential is a little surprising, on top end there usually isn't that much of difference when comparing stock to stock.

Author:  hec2buck [ August 5th, 2016, 9:54 am ]
Post subject:  Re: How high will a 49ci motor rev?

:) Jake, right on the money.

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