Our 2009 ZX-6R was impressive in stock trim but there is nothing like making your way around a race track with a bike that is geared properly for your favorite track.
When it came time to change tires, gearing and controls on our 2009 Kawasaki Ninja ZX-6R Project Bike we had to ask ourselves the same questions you should be asking: What do we want to get out of these changes before we start dumping more money into the motorcycle? It helps to have a plan, but the main goal should be to address any issues with the bike and make changes for the better.
We found that once you get your suspension dialed-in for your weight and riding style, whether its stock or aftermarket, then the best performance gain for the buck that you can make is tires. There are so many street bike tires available that one of the best things you can do is listen and watch what is going on at the track you ride at the most. Some types of tires hold up better in different conditions and on different track surfaces. Hopefully you have a network of riders you can use as a resource when it comes time to make this decision too. For our purposes we like to run Pirelli Diablo Supercorsas ($199 – $300) at Thunderhill and Spring Mountain. Both tracks are rough on tires but as long as you get the bikes set-up in advance and keep proper tire pressure you should expect to get a good, solid day, possibly even two out of them.
The stock gearing for our 2009 Kawasaki Ninja ZX-6R Project Bike was 16/43 so we decided to improve acceleration a bit by changing to Sunstar Sprockets and a 15/45 configuration.
It takes some effort to get the countershaft nut off so you can change the countershaft sprocket. But once you get the nut removed it will not be that difficult the next time around.
Replacing the stock gearing and going with a smaller chain is an easy way to gain acceleration and shave some tenths off your lap times. We replaced the stock 520 O-ring chain with an RK 520 XW-ring chain. The stock 2009 Kawasaki ZX-6R gearing is 16-front and 43-rear. We went with 15-45 Sunstar sprockets to shorten the gearing up and improve drive off the corner. This reduces top speed figures but it also makes the awesome power of the ZX more accessible. The Sunstar Rear Sprocket will run you $63.99 while the Sunstar countershaft sprocket retails for $26.99.
Changing gearing is a relatively simple, yet messy, proposition that deals specifically with the drive train of your motorcycle. If you are not 100% confident and competent enough to disassemble and reassemble these critical parts, please spend the money to have it installed by a professional. You can locate a nearby Preferred Installer from the Motorcycle Superstore if you have any doubts. Riders will need help getting the countershaft sprocket nut off, unless you happen to also work at a shop with pneumatic tools. Before removing the wheels we suggest trailering the bike to a tire store and convince them to use their strongest air wrench to get the countershaft nut off. It turns out that Kawasaki technicians on the assembly line were a bit overzealous when they ratcheted this nut down, so it’s all but impossible to get it off. We would like to have known that before we spent two hours trying to get it off, but that’s why we are here: To make your lives easier.
Once it’s off, you’re good to go. You don’t want to do that song and dance a second time. Remove the stock sprocket and replace it with the new one. Simply torque the nut back to spec and fold the safety washer over to keep it in place. Swapping the rear is considerably easier. Remove the rear wheel, set it on a piece of cardboard, disc side down and remove the nuts and bolts that attach the OEM sprocket to the wheel. Swap out the OEM sprocket for the new Sunstar sprockets and we’re good to go.
On the track the increased acceleration off the corner pays dividends well worth the hassle of hauling the ZX to a shop for help.
The tricky part is once you get the wheel back on, you will need to cut the chain to length. We like to use a Motion-Pro chain breaker ($72.95) which pushes the pin through and makes for a nice clean process. No grinders or hack saws here. This is 2009, not 1988. Actually, was the old grinder routine ever a good option? Anyway, if things go like they did for us you will come to a huge decision. Do you cut an extra link out and cinch the chain tight against the adjusters or leave a lot of slack and use the very end of the adjustment range?
We let our tires dictate the decision. In this case we were running Pirelli Diablo Supercorsas ($199 – $300) so if we cut it short there would have been almost no clearance between the tire and inside of the swingarm so we opted to leave the chain longer. Once it stretches out you can go and remove another link later.