FLASHRACER
Registered
JUST IN CASE YOU FORGOT
GEAR SPEED RATIO
- Thread starter FLASHRACER
- Start date
I noticed the gearing is 17/40. That's the gearing for the Gen-1 Busa. The Gen-2 is 18/43.
You can change it, thats the point of it. there are more <2008 than 2008's.
I made this page years ago, glad to see busa bothers still getting some use out of it.
Very Cool, how come I didnt find that in 1999
Thanx
Thanx
The thing that gets me is it shows that with stock gearing @ 10,800rpms you would be doing 201mph. Why doesn't that work in the real world ? I know that air drag and rolling resistance is a factor in getting that fast, but if your motor is showing 10,800 why won't the busa do it ? For the motor to be turning that fast it turns the gears a certain amount which turns the wheels a certain amount . So Then the only option is that the clutch would have to be slipping . The only reason I ask is because NO hayabusa with stock gearing has gone 201 with stock gearing even when topped out at 10,800 rpms . It always takes more HP and different gearing.
Dobieman
Registered
assuming were talking about unrestricted motor, and that the chart is correct. Its lack of power.
Have you seen 10800 rpm in 6th gear ?
there isn't enough force to overcome the drag. You wouldn't get to 10800 on the tach unless you had much smaller tires, but that would mean you're not going as fast...
Its been tried over and over again ( on unrestricted motors ) You need more power to get over 200. A taller tire like pirellis are good for speed runs . So what you are saying is that with "STOCK GEARING" and a unrestricted motor that has more HP You can get your busa to over 200 . I'm just wondering why I've never heard of ANYONE doing it . It always takes different gearing . I understand that a stock busa can't do over 200 ( at least i've never seen it ). I've been riding busas for 5 years now and I know that I need to change my gearing for a 200 mph run . I know that it has to be unristricted and I do have the HP . But if you take away wind resistance say on a DYNO how come a 99 busa with stock gearing won't show 200 top speed ?
V8Pinto
Registered
I ran 17/39 at Bonneville and went 191.6MPH (top speed in Prod 1350 class). That was at 10,600 on the stock tach.
I was gaining about 200rpm (~1.5MPH) per mile traveled at the exit of the 5 mile.
Pat Womack was running 18/40 and was about 10,200-10,400 IIRC and maybe a half a MPH slower. (should have seen him screaming across the salt - very exciting!)
I was gaining about 200rpm (~1.5MPH) per mile traveled at the exit of the 5 mile.
Pat Womack was running 18/40 and was about 10,200-10,400 IIRC and maybe a half a MPH slower. (should have seen him screaming across the salt - very exciting!)
That is what I mean, even with 17/39 gearing you would not reach 200. With HP aside you would have made 10,800 and only been a couple MPH faster right ?
So how does a 17/40 gearing get you to 201? It doesn't , the graph is like a Suzuki speedo , OFF!
there's so much to figure out and when it comes to gearing it most leastly test & tune... It also involves the distance/time to reach max velocity. With Bonneville you've got to account for the low friction coefficient and make sure you have enough drive wheel weight.
as an example: at Maxton, without changes to my hp or the conditions I ran steady 202's mph @ 10.3k's rpm with 18/40. I only switched the gearing to 18/38 and ran 207's @ 10k's. This was without tire spin. Could the cause be that I'm able to launch harder and stay in it longer during 1st & 2nd? Possibly, but my g meter wasn't very different between the runs... I'm leaning to my average thrust being better since my engine peaks lower than 10k.
as an example: at Maxton, without changes to my hp or the conditions I ran steady 202's mph @ 10.3k's rpm with 18/40. I only switched the gearing to 18/38 and ran 207's @ 10k's. This was without tire spin. Could the cause be that I'm able to launch harder and stay in it longer during 1st & 2nd? Possibly, but my g meter wasn't very different between the runs... I'm leaning to my average thrust being better since my engine peaks lower than 10k.
with the right tires and a good launch / run it would be possible. At Bonneville I don't think it could be done. Your tire slip would be to much.
Reality is the difference. Its a straightforward calculation from engine rpm to gearing, just to give a baseline to work with. There is a lot of force back onto the bike at those speeds , so maybe clutch or tire slippage. Realize also, that 1" in tire circumference and 200 rpm off equates to 6+mph difference in calculation. Is the rpm gauge accurate or did the guy have the balls to get an accurate reading at speed?
Maybe V8Pinto was running 74" cir. tires and his rpm gauge was off 150 from reality.
Also Cummta_Busa above runs 202mph @ 10300 with 18/40, no tire spin, ok so we figure his actual tire circumference to be 76.8". With the same tire cir., he changes only gearing to 18/38 and runs 207mph @ 10k rpms, in line with the calculation.
Gearing choice should be made with peak rwhp at ? rpm, in mind.
Don't get me wrong, I think its a kool site. I just mentioned that because I noticed this was placed in the '08 forum.You can change it, thats the point of it. there are more <2008 than 2008's.
I made this page years ago, glad to see busa bothers still getting some use out of it.
From my understanding the reason is, just like the speedo is off, so is the tech.
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