Hello i just bought a 2008 R6 and have some gearing questions.Ive been told and read that dropping a tooth off the front sprocket and maybe adding 1-3 in the rear will pep it up a bunch.So my questions are this...how much top end do you lose?Also will my speedo be off by much?Im thinking of just dropping 1 in the front and trying that.If i go that route will i need a speedo healer and will i notice a difference?

I have just done this on my 99. I dropped 1 in the front and it made my speedo read 5mph fast so if the speedo says 40mph I am really going 35mph. I think you will like the diff I do. you can always go 2 up in the rear later if you dont feel 1 down is enough. good luck hope I helped

Hey thanks allot for the feedback.Ya i was thinking of just starting with -1 in front and seeing how i like it.The only thing i dont like is racking up miles on the odometer faster.I plan on keeping the bike awhile but i dont wanna kick myself in the but when i go to buy a newer one later on down the road and the miles on the odometer are a turnoff for a would be buyer if i need to sell it.

if you have the extra funds get a speedo healer and that will take care of racking up the miles.

Your stock gearing is 45/16 or 45 teeth on the rear sprocket and 16 teeth on the front. This equals a 2.8125 gear ratio in stock trim.

If you dropped a tooth on the front you would have 45/15 gearing or a 3.0 gear ratio. This is a little more then a 6% change in your stock ratio.

3.0 is also the original stock ratio of previous generation R6's. Personally I run a 50/15 which is a 3.3 ratio on my '02, with this I can chase down even the best litre bikes at the race track.

If you go 45/15 for every 100 miles you ride your speedo will see 106 miles. This isn't a huge difference. Over 10k miles it will change your speedo 600miles.

If you started adding teeth in the rear you ratios would change as follows:
45/15 = 3.00 or 6.67% from stock
46/15 = 3.06 or 9.04% from stock
47/15 = 3.13 or 11.41% from stock
48/15 = 3.20 or 13.78% from stock
49/15 = 3.27 or 16.15% from stock
50/15 = 3.33 or 18.51% from stock

You questioned the effect on top speed.

Here is a gearing calculator based on the '99 model YZF-R6:

http://www.yzfr6.net/sprocket_speed.php

The first generation R6's were good to about 156mph and then were "drag limited", much like your bike. It was possible to go slightly faster in 5th then 6th since in 5th you were going 156mph at about 14.5k rpm instead of 13.5k rpm in 6th, at the higher rpm the bike made more power and had more push. Theoretical top speed is listed at 180mph, impossible.

If you alter the gearing to say 48/15, or drop a tooth in the front, your theoretical top speed is still beyond stock reaches at 169mph. If you look where 156mph falls in 6th gear it is now in the 14.5k rpm range, or the same as 5th gear was with stock sprockets. So now you could pull 5th gear all the way to redline, which you couldn't do in stock trim, to 153mph then shift to 6th with all the power in the world and hold 156mph maybe push to 157/158mph.

Even switching to 50/15, you're still under the drag limited topspeed and have a theoretical top end of 162mph. This is an 11.11% gearing change from stock on my bike. The bike is quicker in acceleration and faster in top speed. Even though my topspeed has come down from 180mph to 162mph I can now more easily get to 156mph and more.

The basic reason is the motor is spinning faster and making more power to do the same work as before. The added power availible makes it possible to do more work then before. So with altered gearing, even though you lose theoretical topspeed, you gain usable real world topspeed.

so on my 07 r6 (non s) if i do a 15-48 how much is it going to effect the over all performance of my bike. im looking for quicker acceleration and more power out of it.