Landracing Forum
El Mirage => El Mirage General Chat => Topic started by: V8Pinto on June 22, 2007, 11:43:48 AM
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I'm currently running stock gearing (I think that's 17/40) and the bike didn't quite feel like it would pull redline in 6th (about 10,500 on the tach with redline somewhere around 11,000).
I'm planning some very small changes (filter, stacks, that sort of thing) and a re-map. Is there any reason I should change gearing yet? I think the early bikes had 18/40 gearing so I was considering swapping to that just to see but I don't want to end up slower.
Thought I would ask those that are more in the know.
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I ran right at 187 on Michelle's Blue Busa (stock with an un-mapped Yosh pipe) with stock gearing and the bike was lacking the HP at El Mirage to run any faster. (the bike is fitted with a TRE)
I would think you would need a considerable amount of HP to be able to pull the 18-40 gearing..?
J
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I'm currently running stock gearing (I think that's 17/40) and the bike didn't quite feel like it would pull redline in 6th (about 10,500 on the tach with redline somewhere around 11,000).
I'm planning some very small changes (filter, stacks, that sort of thing) and a re-map. Is there any reason I should change gearing yet? I think the early bikes had 18/40 gearing so I was considering swapping to that just to see but I don't want to end up slower.
Thought I would ask those that are more in the know.
If it would help I have spreadsheets that will show your speeds in all the gears along with side by side speeds in 6th for different sprocket combinations here:
http://purplesagetradingpost.com/sumner/bvillecar/bville-spreadsheet-index.html
c ya,
Sum
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Thanks for the spreadsheet, Sumner. I plugged the Busa gearing into it and the quoted tire diameter from the Bridgestone specs. At 180Mph the rpms are listed as ~9,600. I was at 10,500 indicated on the tach which sounds about right for a thumbnail guess on wheelspin. Also, my tire is worn so that changes the rolling circumference etc...I'm going to see if I can measure the tire diameter to get a more accurate number to plug in there.
John,
At 187 was Michelle's blue Busa pulling redline? What year is the bike? (17 or 18 tooth front).
Thanks for the help!
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....................I'm going to see if I can measure the tire diameter to get a more accurate number to plug in there.................
I know our rpm from the data logs at the 5 and the exit speed at the 5. From there I had to change the tire size slightly to get the rpm to match exactly.
We also might of had tire spin there that would have effected it and also when Hooley tore the car down recently he found the clutch was burned up and had been slipping, so that could have been it also or it could have been tire growth.
With the spreadsheet you can always fudge it a little by moving the tire size around to get the data correct if you do indeed know what is correct :roll:.
To me what the spreadsheets can help the most with besides seeing your speed in each gear, which can prove handy on a license run where you might not see high gear, is that it shows you the rpm drop between gears at any mph which could help in cam selection to make sure you stay in the power band and/or help you decide when to shift.
c ya,
Sum
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I'm currently running stock gearing (I think that's 17/40) and the bike didn't quite feel like it would pull redline in 6th (about 10,500 on the tach with redline somewhere around 11,000).
I'm planning some very small changes (filter, stacks, that sort of thing) and a re-map. Is there any reason I should change gearing yet? I think the early bikes had 18/40 gearing so I was considering swapping to that just to see but I don't want to end up slower.
Thought I would ask those that are more in the know.
What LSR Course?I know Bonneville has Hurt allot of Feelings when it comes to How Fast a STOCK Bike can Really go :wink: :wink:
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Thanks for the spreadsheet, Sumner. I plugged the Busa gearing into it and the quoted tire diameter from the Bridgestone specs. At 180Mph the rpms are listed as ~9,600. I was at 10,500 indicated on the tach which sounds about right for a thumbnail guess on wheelspin. Also, my tire is worn so that changes the rolling circumference etc...I'm going to see if I can measure the tire diameter to get a more accurate number to plug in there.
John,
At 187 was Michelle's blue Busa pulling redline? What year is the bike? (17 or 18 tooth front).
Thanks for the help!
Michelle's Aspirated bike is a 2001 and stock gearing on all Busa's from 99-2007 are 17 front and 40 rear.
The bike was not at Redline however the bike was never mapped for the bolt on exhaust system and we were running at Elmo, this was done without any other mods to the engine..the brakes were not even spread open..so I am sure that with a few more ponies someone could run over 190
Are you coming out in July ? ?
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Thanks that helps a lot. My bike (2006 Busa) was the same way - wouldn't pull redline (at El Mirage). Based on what I've learned in this thread, I am going to save the gearing mod until I've built a lot more power. I will focus on whatever mods are allowed in P-P and do those first.
That "brake spread" sounds like it would be really interesting the first time you squeeze the lever in the shut down area :)
I *hope* to make it in July - I probably won't know if I'm going until the week before.
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Shane,
If we can help let us know..
Good luck.
J