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Discussion Starter · #1 ·
I didn't see any top speed figures anywhere. I read the MT is good for 133 mph with 66 whp. With the better aerodynamics and gearing, I think the R7 would be good for about 10 more. And it shouldn't be too difficult to get over 150 mph with external mods.
 

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Previously 2001 Suzuki TL1000R, On Order: 2022 Yamaha YZF-R7 BLue, On order: 2022 Honda Grom Yellow.
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To get from 143mph to 150mph... I remember reading about this stuff a while back...

Air resistance increases as the square of the speed increase.. It’s a non-linear relationship. Double the speed... you get 4 times the air resistance.

horsepower must increase as a cube of the speed increase... another non-linear relationship. Double the speed, you need 8 times the horsepower.

let’s assume the R7 does have a top speed from the factory of 143 with 74hp. We don’t know exactly how much hp it has yet, so we’ll make some assumptions to figure out what’s needed to get to 150mph:

150/143=1.04895
Cube that and you get 1.154 times the starting horsepower.

So to get to 150mph it requires us to find 15.4% more power than the bike comes with. So can approximate that we need to have 74 * 1.154 = 85.396 hp... with no other changes in circumstances.

So theoretically about 11.4hp more would be needed to get to 150.
 

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Discussion Starter · #3 ·
CW dyno got 67 whp for the FZ which seems about right if Yamaha claims 74 at the crank. The R7 is supposed to have the same output. Here's a chart showing the difference aerodynamics makes with a typical 200 hp bike. The smaller frontal areas of the MT and R7 will require less hp so the actual speeds for both will be about 8% higher than shown.

 

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Previously 2001 Suzuki TL1000R, On Order: 2022 Yamaha YZF-R7 BLue, On order: 2022 Honda Grom Yellow.
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Cool! Yeah, that picture is a great visual to explain the cube function of the power needed for speed increase, and it does it with 2 different drag coefficient examples. We can see that the graph is spot on with both curves if we take samples from it. Great find EDS!

So, by way of a claimed data point from Yamaha of the R7 being able to do about 10mph more than the MT07, that means the R7 can do 143mph (again according to Yamaha), with a best guess of 67 rwhp.

67 * 1.154 = 77.318

According to the formula illustrated on the picture, We’d need to find about 10.3 rwhp to theoretically make 150mph, if all other circumstances remain unchanged.

Im such a nerd. Lol
 

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Discussion Starter · #5 ·
The rear sprocket on the R7 has 1 less tooth so that gives a 3+ mph (to 137ish mph) increase for the same rpm and if the aerodynamics are as good as Yamaha claims, I think 140 mph or more stock is easily possible. The chart shows a bike with more drag so I don't think it'll take much more hp to get to 150. Maybe an exhaust system and flash is all it takes. Not sure where peak power ends in relation to top speed but from what I read, it's nowhere near red line.
 

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Previously 2001 Suzuki TL1000R, On Order: 2022 Yamaha YZF-R7 BLue, On order: 2022 Honda Grom Yellow.
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I agree with most of what you’ve presented. One thing about the slightly taller gearing from the 42 tooth sprocket of the R7, is that at any given speed, the engine (supposedly identical) is running at a slightly lower rpm. So it’s output is different (and likely lower) at any given identical speed.

That extra theoretical 3 mph at the same rpm you mention... 3 mph from 133 to 136 at the same engine rpm requires it to put out 4.6 more horsepower to achieve, with the MT07 drag coefficient. This is to illustrate that a taller gear to make rpms available does not equate to higher speed capability. The R7 achieved the higher speed more so through reducing drag.

We’ve wandered into the weeds a bit. I’m going to turn this back toward the original question.

Yamaha has already claimed “about 10 more mph for a stock R7 over a stock MT07” due to a lower drag coefficient, and other small changes so all the details are accounted for and Yamaha told us what they got. If a stock MT07 does 133mph for example, then a stock R7 under the same conditions should do about 143mph(10mph more).

143mph of a stock R7 was the known starting data point in the question. That made answering the question real simple, so we need not overthink it. So we applied a known formula to answer the original question about getting the bike to 150mph under the exact same conditions that established the 143.
 

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Discussion Starter · #7 ·
Thank you. I didn't see where Yamaha claimed 10 mph higher than the MT. The sprocket change should only increase speed 3 mph for the same rpm so that 10 mph increase is at higher revs. One of these bikes is maxing out too early or too late and isn't geared for highest speed possible. I wanna be able to do power wheelies so I won't be going any smaller on the rear sprocket anyway even if it means a higher speed which I'll never see.
 
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