By adding a 17 tooth countershaft sprocket we will accomplish several things:

We will be able to lower the revs at highway speeds to get away from the buzzy rpm range of the motor when at highway speeds or greater for long durations.

Shorten the wheelbase slightly which quickens steering a tad & takes some more slack out of the chain which is a couple of links to long

& it will help to correct the inherent speedometer error of the bike making it read much more accurately

The down side is we are going to give up some acceleration, but I think it will be a fair trade off if you do any type of long commuting or weekend trips.

UPDATE: This is the mod EVERY 919 owner is now doing with hundreds of these kits having been sold. The top of the line 520 17/44 conversion chain kits can be had for $199 plus shipping right here

UPDATE: 02/11/04

I have now added a 44 tooth rear sprocket to the 17t countershaft. After several months of testing & riding in all conditions I feel this is the best overall compromise for gearing. My cheap ass OEM chain is nearly wore out, can easily hear links rattling when flicking it with my fingers & I will be replacing it with a DID ERV chain soon, but intend to keep the stock length of chain so I may continue to use the 17/44 gearing combo & maintain the current wheelbase.

UPDATE: 02/01/03

I love this mod! The difference in acceleration riding solo is only barely perceived, but of course if you are in direct competition with a 929, R1 etc out in the twisties well then the performance gap only gets worse.

However if you are out for your own enjoyment of riding the 919 at your own pace then this is a sweet mod especially since it is sooo cheap to do. I personally feel that 1st gear is now much more usable than with the stock sprocket & yes even with a full tank of fuel & my 200lb ass it will still loft the front sky high with a quick snap of the wrist. An indicated 60mph now comes at 3500rpm & 6000rpm will put your nose on 100mph which corresponds almost perfectly with the
gearing spreadsheet (excel)

UPDATE: 01/29/03

First & foremost for the nay-sayers the 17tooth sprocket does fit & can be installed without removing the rear wheel. All you need to do is loosen the axle nut & move the chain adjusters as far forward as they will go.

You will also find that this takes a lot of the extra slack out of the chain that pretty much every owner is in agreement with the opinion of it being 2 links too long

stock 16 tooth sprocket

17 tooth AFAM sprocket