Gears/MPH question

[Tetge]

I have been searching since I got my new Busa and I still am confused about how many MPH/1000 the bike turns in 6th gear.  My speedo says 77 mph @ 4000 RPM but, it has been said that the speedo could be wildly inaccurate.  I did calculations of speeds in gear using 77 @ 4K in 6th as the basis and in fact, it does seem that the speedo is reading too high.  Next, I read that the 184 governor is achieved by limiting 6th gear RPM to 10200.  So, if 10200 = 184 MPH, then 6th is geared approx 18.03 MPH/1000 and the indicated 77 at 4000 would actually only be 72 mph.  That's a pretty bad speedo error at only 70, and 18.03/1000 appears to be a bit low based upon observations at the drag strip.
So, have those with stock gearing and rear tires and accurate speedometers or GPS, or both, actually determined the MPH/1000 RPM in 6th for the Busa?  I need this info since, based upon my primitive calculations, regearing my bike to 16/42 might hurt my 1/4 at LACR.  The 11% shorter gearing with 16/42 still does not bridge the big gap of 18.75% between 3rd and 4th. Right now 3rd is just about wound out in the 1/4, although that does not match the calculations that I made based upon the observed speedo speeds of my bike.
Sorry for the long post, but, unfortunately, I obsess on gearing, and I hate to get it wrong. I know my trap speeds so, if I know the accurate MPH/1000 in 6th stock, I can accurately calculate how gearing changes will impact me.



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[brad]

Try http://home.cfl.rr.com/redbusa/gearspeedcalc/index.html. This link will allow you to formulate different gear changes (final drive sprockets). Remember it does not take in to account rolling resistence (minimal) or wind resistence (wind drag).

Brad

 

[Tetge]

Thanks for the reply. It is as nice calculator but, according to it, 10200 RPM in 6th would be 190 so there is still that conflict between the posts indicating that the bike is governed to 10200 = 184 in 6th and the calculations. The calculator assumes a 77" tire circumference. I was just wondering what people with stock gears and GPS were observing?

 

[GOD]

4000 rpm at 72 is right.......I have a video i took (with the camera on the gas tank) and it showed that at 70 mph it was just below 4000 and at at 72 is 4000! I have a speedo healer so my speedo is accurate, stock tires, and stock gearing. I don't know the exsact percentage that the speedo is off with stock guages, but I think it's around 10%. .....btw with aftermarket guages that show 220mph the error percentage is 24%.

 

[GOD]

well, I guess if i calculate your error, it would be 10% since at 4000rpm you are going 72, but your guage shows 77.

hope this helps