RE: top speed?

CBR Forum Classifieds News Photo Gallery Search Member List Timeslips Contact Sponsors Register Login

RE: top speed?

Printable Version

CBR Forums >> Past CBR Models >> CBR 900RR >> RE: top speed?

Page: << < prev 1 2 3 [4]

Message

<< Older Topic Newer Topic >>

RE: top speed? - 11/3/2006 9:39:11 PM

ducatijay

Posts: 57
Joined: 2/15/2006
Status: offline

what?? has everyone gone insane??

first, mustang example is a bad one. (i thought mustangs had 5spd trannys, maybe the new body ones). the sixth gear was never intended for "top speed." it's an overdrive gear for fuel economy.

second, yes, in theory, i can keep lowering my final drive ratio until the motorcycle doesn't make enough power to keep pulling. but that's not what we're talking about. we're talking about a 1-3 tooth change.

okay, for arguement's sake let's say redline is 12,000 rpm and peak power is 10,800. this motorcycle will be faster at 12000 rpm not 10800. just by simple math, the rear wheel will spin faster at 12k than 10k. we're not looking for peak power, we're looking for enough power to pull the final drive ratio. if the RR can run out of gear in sixth (which it can), raising the final drive (- in the front, + in the rear) will make the bike slower (top speed). even if you're at peak power at the end of the gear. peak power has nothing to do with how many rotations the rear wheel makes in relation to the motor, gearing does.

anyway, back to the original statement. no RR (relatively stock) is running in the 180s. we know speedos are inaccurate. and once you change the final drive (except on bikes with front wheel speedo drives), it will be even more inaccurate. that why people are seeing higher top speed numbers after raising final drive.

woody900rr- you were right before no need for apologys........

Thumbnail Image

Thumbnail Image

Attachment (2)

(in reply to woody900rr)

Post #: 46

RE: top speed? - 11/4/2006 11:51:06 AM

Skater

Posts: 44
Joined: 4/8/2006
Status: offline

Ducatti, first the mustang example (maybe it wasn't a mustang, not the point) illustrates perfectly that you must have the right gear to get top speed. Like you said, 6th was never meant for top speed, it's too big.
Second, lowering the final drive was just an extreme example. I find going to extremes makes things more obvious.
Finally, I do agree that a bike at will be going faster at 12000rpm than 10000rpm is a given gear, and that if the bike has reached redline, -1f and +3r WILL make the bike slower. I think that is a no brainer. If you have reached redline, then you must +1f, -2r (for arguments sake) so that you have more room in the rpm's. However, if you do drop the final drive too much ("mustang" example) then the engine can't pull it because it is not in the peak power, so then you must raise the final a bit to get it in the peak power.
And really finally, a brand new CBR1000, or an 04 GSXR1000 has 141 rear wheel horse power and are both WAY more aerodynamic than a 1992-1999 cbr900, and they do 180. An older 2003 GSRX has 135 rear wheel horse and did 178mph,according to Superbike magazine in DEC 2005. 6 horespower increase for 2 mph. Remember that areodynamic drag is relative to the square of velocity, so a small increase in velocity results in a large increase in drag. Its not proportional. So anything under 130 rear wheel horse in a stock cbr body is not going to do 180mph. Stock 1995 cbr900rr max 165mph, acording to SEVERAL magazines.
I look forward to the next rebuttle.
(PS it sucks that winter has struck here in Calgary, Canada. No bike for at least 6 months!)

_____________________________

UB6 IB9

(in reply to ducatijay)

Post #: 47

RE: top speed? - 11/4/2006 9:11:58 PM

ducatijay

Posts: 57
Joined: 2/15/2006
Status: offline

SKATER-i agree with everything you just posted. how you ended it was perfect!!! no one on a relatively stock RR is running anywhere near 180s.

i had my '06 zx10r on the back straight of pocono international topped out at 184. i couldn't believe people would post there old RR could run that fast...

anyway, i posted pics of my '93 RR in my last post. pride of my fleet. but since it only tops out at 151mph, i'll have to sell it. lol.......

(in reply to Skater)

Post #: 48

RE: top speed? - 11/13/2006 1:00:49 PM

sean_carman

Posts: 10
Joined: 6/30/2006
Status: offline

290km with a bit of a tailwind on my 99.

(in reply to Chrisct713)

Post #: 49

RE: top speed? - 11/13/2006 8:52:17 PM

sanders1977

Posts: 58
Joined: 1/1/2006
From: C'ville
Status: offline

Ohh, ohh my 93 900rr was toping out at 165mph, but now that I've put on a ram air filter, 1 step hotter plugs, some overweight exhaust, and blue handle bar grips, I'm bending space and time!!

In all seriousnes, I've seen my needle coming back down in the range of 155, but I must agree that my speedo is most likely off at those speeds. It was still pulling like a beast, but I doubt that she had much more. Besides that small country road was getting mighty narrow at those speeds. Any way, I must be an old fart because when I'm in tripple digets I'm not looking at the gauge cluster, I'm looking out for where the road's going.

(in reply to sean_carman)

Post #: 50