Author Topic: Hayabusa wheelspin estimate?  (Read 4155 times)

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Offline V8Pinto

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Hayabusa wheelspin estimate?
« on: July 06, 2007, 01:23:28 AM »
What sort of wheelspin do bikes experience?  I'm on a stock Busa, stock tires, stock everything. 

I know there are a million variables to this - I'm just looking for somewhere to start - a thumbnail number.  I'm trying to optimize a gearing calculator and I'm getting about 3% wheelspin or .7mph which seems low to me.

Sorry if this is a wacko question, just trying to setup my tools...

Thx for the help.
Shane
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Offline ol38y

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Re: Hayabusa wheelspin estimate?
« Reply #1 on: July 06, 2007, 01:44:16 AM »
As has been said here, your mileage may vary, but the numbers I have seen are in the 7 to 9% range. That's what I'm using anyway. You also might want to keep in mind at the last EM a Busa blew a tire and went down hard. The story I heard was he was spinning the back tire pretty much the whole way. It's all in the wrist, traction control. Just my thoughts.

                              See ya on the salt, Larry
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stayt`ie

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Re: Hayabusa wheelspin estimate?
« Reply #2 on: July 06, 2007, 03:56:40 AM »
depends on red mist and wrist, control both, and aim for 6%  :wink:

Offline Stainless1

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Re: Hayabusa wheelspin estimate?
« Reply #3 on: July 07, 2007, 12:21:30 AM »
What sort of wheelspin do bikes experience?  I'm on a stock Busa, stock tires, stock everything. 

I know there are a million variables to this - I'm just looking for somewhere to start - a thumbnail number.  I'm trying to optimize a gearing calculator and I'm getting about 3% wheelspin or .7mph which seems low to me.

Sorry if this is a wacko question, just trying to setup my tools...

Thx for the help.

17% IS BAD, 7% is good, 3% on salt or dirt is probably excellent, unless it is .7 MPH, then you are going way too slow on a busa
Stainless
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aswracing

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Re: Hayabusa wheelspin estimate?
« Reply #4 on: July 07, 2007, 11:22:35 AM »
I'm getting about 3% wheelspin or .7mph which seems low to me.

If 3% wheelspin is only .7mph, it means your 'busa is going 23.3mph (3% of 23.3 is .7)

You need to do some tuning on the engine. A stock 'busa oughta be able to go a little faster than that.

Assuming you get it sorted out and can get it into the more typical 185mph range for a stock 'busa, 3% would be 5.55mph.

I haven't run the dry lakes, but at the salt flats, running around those speeds, I've seen anywhere from 3% to 12% wheelspin, depending on conditions, which is a huge range. I don't race a 'busa but our fairing is pretty similar CdA wise.

It's one of the unique challenges of this kind of racing. I try my damndest to have my shit together when I roll it out of the trailer, to have the bike as developed and prepped as I possibly can so that we can concentrate on fine tuning only. But until we make that first pass and I gather some wheelspin data, my gearing calculations have a large error factor.
« Last Edit: July 07, 2007, 11:26:56 AM by aswracing »

Offline V8Pinto

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Re: Hayabusa wheelspin estimate?
« Reply #5 on: July 07, 2007, 12:45:42 PM »
Thanks for all the input - here's what I'm working with (all at 10,500rpms indicated on the factory tach).

Actual speed      = 180.7
Indicated speed  = 195ish

The Busa is known to have a (roughly) 7.5% speedometer error.  The difference between actual and indicated is most of that 7.5% which leaves almost nothing for wheelspin (to get my .7mph wheelspin number I added 7.5% to 180.7 and took the difference between that and 195 indicated).

The part that is confusing me is the gearing calculator.  With stock gearing, stock tires, stock everything, at 10,500rpms I should be running 195.  Ok, that works for the "indicated" speed but it's nowhere near the actual.  If I go the other direction and say "at 180mph, what should my rpms be?" I get roughly 9,700rpms which means the tach is off by about 800rpms.

I can understand the speedo error but I would think the tach should be pretty spot-on.  I just can't figure out which instrument is off...  I would like to be able to rely on something and I would like it to be the tach.

Noonan said Michelle's blue busa ran about 187 with the only mod being an exhaust so I am in the ballpark as far as mph goes.  I just wanted to be able to calculate wheelspin but it sure is getting confusing fast.
« Last Edit: July 07, 2007, 12:48:24 PM by V8Pinto »
Shane
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Hayabusa on the brain
Twin-Turbo F150 4x4

Offline Speed Limit 1000

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Re: Hayabusa wheelspin estimate?
« Reply #6 on: July 07, 2007, 01:28:48 PM »
Another unknown is the tire growth at 180 Mph. A data logger with wheel speed front and rear really helps to get a good look at what is going on.
John Gowetski, red hat @ 221.183 MPH MSA Lakester, Bockscar #1000 60 ci normally aspirated w/N20

racin jason

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Re: Hayabusa wheelspin estimate?
« Reply #7 on: July 08, 2007, 02:19:08 AM »
compare the factory tach to one on a dyno and you'll see the factory tach is 5-600rpm high at the top end.

Offline JackD

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Re: Hayabusa wheelspin estimate?
« Reply #8 on: July 08, 2007, 04:09:24 AM »
You have to ask yourself, why is the speedo off but the tach is said to be right on ?
That was true in many cases, but not so much anymore.
When doing many magazine tests, it was proven time and again that the bike that had the greatest sensation of speed was not very often the fastest , but just handled bad.
The OEM people build that little bit of extra excitement into the product so to preserve the thrill without the price of reality.
At traffic speeds, it keeps your tickets down, at speed speeds , it bolsters bragging rights.
Both degrees of error help to sell more UJM products.
On the salt, riding skills and applied technique will get that little bit extra that some never will.
Their is a lot more to it than tire and gear selection. :wink:
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Offline Dean Los Angeles

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Re: Hayabusa wheelspin estimate?
« Reply #9 on: July 08, 2007, 08:57:17 PM »
The speedometer will never be accurate due to tire growth. Front and rear wheel rpm readings will give you the slip differential.

The tachometer can be calibrated with a strobe. I use a Monarch Nova-Strobe PB-115 that is accurate to ±0.01% of reading. You can rent them.
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