This has been on my list of things to do for some time now, and I have finally got round to fitting the new rear sprocket to the bike. I had heard other people had changed the gearing to make their bike quicker or faster top end. I got a rear sprocket from Renthal (£27) with two more teeth than standard. Two teeth is about the most you can go on the standard length chain. Even then, the chain had to be forced on. Optionally, I could have went one less on the front (£8-9) - too lazy, and I liked the look of the Renthal wheels.
What a difference. The front lifts from as little as 3000rpm in first. Power wheelies are available on demand in second - just give a little tug and up she comes. Whether or not it is actually quicker overall is a bit hard to tell - it will not take full throttle in first, so that must slow things down a bit. Still, the ability to pose pulling away from the lights is huge. I have already had people asking me what I have done to make it wheelie so easily and the sprocket had only been on for two days! Once it is in second or above, there seems to be more thrust than before. In fact, it is a bit like the change in performance after the can / jetting was done. I guess it is the equivalent of about 7-8bhp.
The only bikes that I have really bench marked it against are a couple of R1's. The first one was standard and it was quite easy to pull more than a couple of bike lengths from 40 - 110mph. The second had a Akropovic pipe. Sitting behind the R1, and waiting for it to go first (e.g. overtaking cars), the R1 instantly pulls out a bike length (he gets on the throttle first mind). But, afterwards the gap slowly but surely closes. 100mph later, the roles are reversed. Not bad for the 'slowest sportsbike about'.
The down sides? Well, the speedo reads even more out. Before, sitting at a true 50mph (well, true according to the cycle computer) the speedo read 54mph. Now it reads 56mph. At 80mph, the speedo sits at just under 90mph. Also, a couple of times I have tried to change into sixth only to realise I was already there (I am getting used to this now). The drop in top speed works out to be 8mph, but I doubt I shall miss that.
The only down side is that it shakes its head quite a bit more - not quite bad enough for me to think about a steering damper - just enough to make you feel like a hero!!!
If you are planning to do this, the ratios go like this - in order least change to most. Standard is 16 tooth on the front and 41 on the rear.
Up one tooth on the rear - 2.4%.
Up two teeth on the rear - 4.7%.
Down one tooth on the front - 6.2%.