Just put on a 15 tooth Vortex front sprocket and it was the best $23 I have ever spent. I can really tell a difference in the acceleration and torque! Its alot easier to pop wheelies now! It did throw off my speedometer about 5 mph for every 50 mph, so if my speedo says 50 I'm really doing 45, and if it shows 150 I'm really doing 135. This is the best mod I have done to my bike for the price!

 

what has it done to your rpms?

what rpm did you used to run at if you were going 60mph?
now what rpm do you run at going 60mph?

thinking about doing the same thing, but not sure if I want to put up with the added engine speed at higher cruising speeds.

 

It hasn't changed my rpms alot, except that they shoot up more quickly now! It completely cuts out the lag in the 5-7K range. When I'm in 6th gear doing 60 mph its at 4750 rpms, when I'm in 3rd at 60 mph im at 7k rpms. and as far as top end, I hit 160mph before the change and then did the same with the 15 tooth and it still had room to go faster. And just in case you're wondering my friend on his R1 was behind me double checking my speed... If I was you, I wouldnt think twice about doing this mod, unless you want to go up 2 or 3 teeth on the rear, its all about the same except the front is easier to do! If you have any more questions let me know.

 

I have a similiar set up gearing wise, but it is a 520 chain conversion. I just went to the track yesterday and it definetly helps the drive out of the slower corners and it does wheelie better now also..besides the speedo error also remember your mileage will not be accurate...so if you are changing your oil in mileage intervals you can go longer since the mileage is not correct..I would suggest that over 3000 miles the error would be somewhere around 500 miles..so I am shooting for oil changes at 3500 instead of 3000. I dont think it really makes that much of a difference, it is just something to think about

 

Where did you get it for $23?

 

Edge 2 Edge Moto They have the best prices on everything. I have yet to find someone cheaper than them!

 

Cool, Ill check them out! Thanks!

 

Let me know if you find what you need, if not I will help you find it. I am still impressed by the difference in acceleration. My friends r1 no longer runs off and leaves me.... as bad!!

 

Changine the front sprocket shouldn't change your rpm's at all. The F4 doesn't have the speedo cable, that the earlier models did, on the front tire. I just did the 520 conversion on my bike a few months ago and I love it!!

 

Changing the front or the rear sprocket will definately affect your speedometer reading since it is driven off the transmisson, since its the gearing it WILL alter your RPMs...drive your bike at 70 MPH with the stock gearing and notice what RPM it is pulling, now change it and see what your speedo reads at the same speed...the RPM will be higher with the different gearing