Sportbike Easy Upgrades: Accelerating Faster and Decelerating Better

This is what the flare tool looks like installed. It took a couple tries to find the proper orientation of the tool to do the job.

Here are my “slight, pronounced flares” per the instructions. I did weigh the chain and sprockets, old versus new, using my bathroom scale which has a resolution of 0.2 lbs. The new parts came in at 1.0 lbs lighter, so figure +/- 0.1 lbs due to the scale resolution.

To take it out for a test ride, I called a buddy up with his new ND Miata and we headed up Angeles Crest Highway with a stop at Newcomb’s Ranch. First thing, with the stretched out original chain, the bike was a bit jerky when getting on/off the throttle due to all the slop in the chain; so, the new chain made the bike smoother to ride again. And the gain in acceleration was instantly noticeable.

The rear Pirelli Diablo Supercorsa SP tire I installed a while back was significantly taller than the Michelin Pilot Power 2CT I had on before, which cost me some acceleration. Going down 1 tooth on the front made my gearing shorter by ~7%, and that was a very nice improvement in acceleration, more than overcoming the acceleration I lost with the taller rear tire. The shorter gearing definitely makes the bike more fun in the canyons and more entertaining to wring out the engine to 15k rpms. Also, the ND Miata makes for a fun dance partner up in the canyons.

One area I’ve been annoyed with for a while on my 2005 CBR is the brake fluid reservoir. The issue the past year (or two?) has been getting a mushy brake lever where I have to flush the fluid every few months. I tried changing out the black rubber gasket to a new OEM one, but that only worked for a few months.

So, in comes the OEM + upgrade from the 2007+ CBR 600RR. The new brake master cylinder has a cylindrical fluid reservoir like every other sportbike out there.  Make sure to get the 2007 lever, lever bolt, and cap nut too.

1 comment

  1. Great article Khiem. These ‘quick’ acceleration kits are great for road use bikes where standard gearing is usually far too long. Not that one front tooth makes a huge difference, but the longer wheelbase that you’re afforded by using a smaller front sprocket also has some beneficial effects – mostly moving the center of mass forward toward the front wheel helping hard acceleration and cornering.

    I’ve got another new to me 675 Triumph I’ll be uploading more about soon as well as finally more track time to dial in the 998 next weekend. Thanks for the link.

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