Tried for a top speed run today

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Reciprocal
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Re: Tried for a top speed run today

Post by Reciprocal » Wed Jul 03, 2019 3:25 pm


Switch18 wrote:
Wed Jul 03, 2019 10:03 am
Surely at altitude your bike will be loosing power as there is less air. Also the drag from your back pack will loose you more mph
It will lose power and don't call me Shirley. But seriously, the power loss should be linear. But as a golf ball flies farther in thin air, so too should there be less drag resistance parting thinner air. Not only less drag, but exponentially so. At what exact point the reduction in drag becomes more significant to speed than the reduction in power (if it ever does), who can say?

Does anybody doing speed runs tuck completely behind the windscreen where you have to look through it? :no: #birdboxchallenge
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Re: Tried for a top speed run today

Post by cOoTeR » Wed Jul 03, 2019 3:57 pm


Reciprocal wrote:
Wed Jul 03, 2019 3:25 pm
Switch18 wrote:
Wed Jul 03, 2019 10:03 am
Surely at altitude your bike will be loosing power as there is less air. Also the drag from your back pack will loose you more mph
It will lose power and don't call me Shirley. But seriously, the power loss should be linear. But as a golf ball flies farther in thin air, so too should there be less drag resistance parting thinner air. Not only less drag, but exponentially so. At what exact point the reduction in drag becomes more significant to speed than the reduction in power (if it ever does), who can say?

Does anybody doing speed runs tuck completely behind the windscreen where you have to look through it? :no: #birdboxchallenge
I think drag is your limiting factor coupled with the elevation and heat. It's almost like the bike is designed aerodynamically (if that's a word) to work great up to a true 185mph. My bike got up to 185 quickly and smoothly then it started creeping slowly to go faster. The backpack on the back of your bike is most likely throwing the aerodynamics of the bike off. If you look at streamlined land speed machines there is a lot of focus on designing the rear of the vehicle, turbulence is bad.

When I do top speed runs or drag races I'm tucked fully behind the screen and can see fine. You're focus needs to be WAY down the "track" at 160+ mph not at the side of the road just infront of the bike. I put the chin of my helmet right on the tank. I also focus on getting my butt all the way back in the seat after clicking into 5th, pulling my elbows in tight, feet in close and try to get the soles of my boots flat with the ground. At the half mile race I did it made a difference in my trap speeds.
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Stock with airfilter 164whp 84ft.lbs
De-restricted + tuned 213whp 97ft.lbs
Full vandemon exhaust with tune 221whp 99ft.lbs
On Race Fuel 233whp 103ft.lbs

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Switch18
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Re: Tried for a top speed run today

Post by Switch18 » Wed Jul 03, 2019 4:39 pm


I concur with cOoTeR,s advice. I was achieving a good 5-8mph more once I had sorted out my body position. The correct screen will also help.
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Re: Tried for a top speed run today

Post by h2lsr » Sun Jul 07, 2019 2:52 pm


I'm surprised that you did not achieve a higher top speed with 233 rwhp!

I have a 2016 H2 with head, cams and stage 3 gears (353 rwhp) and get 238.1 mph gps on PUMP gas in one mile :)
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Re: Tried for a top speed run today

Post by cOoTeR » Sun Jul 07, 2019 6:08 pm


h2lsr wrote:
Sun Jul 07, 2019 2:52 pm
I'm surprised that you did not achieve a higher top speed with 233 rwhp!

I have a 2016 H2 with head, cams and stage 3 gears (353 rwhp) and get 238.1 mph gps on PUMP gas in one mile :)
H2 is a completely different bike with different aerodynamics. All my top speed runs were done on pump gas at elevation. So you're 130whp more than mine. I'm also at stock gearing. If you tune your bike down to 220whp and add about 50lbs to it you may not be too surprised.
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Stock with airfilter 164whp 84ft.lbs
De-restricted + tuned 213whp 97ft.lbs
Full vandemon exhaust with tune 221whp 99ft.lbs
On Race Fuel 233whp 103ft.lbs

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Re: Tried for a top speed run today

Post by Prof J » Thu Jul 11, 2019 4:22 am


h2lsr wrote:
Sun Jul 07, 2019 2:52 pm
I'm surprised that you did not achieve a higher top speed with 233 rwhp!

I have a 2016 H2 with head, cams and stage 3 gears (353 rwhp) and get 238.1 mph gps on PUMP gas in one mile :)
h2lsr,

I don't think your bike is a fair comparison . . .

in this universe. :)
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