1. J

    1 or two teeth smaller rear sprocket consequences

    Hey, thinking about putting a slightly smaller rear sprocket on at one time. I know Formula390 knows this stuff inside and out. Iknow there will be slightly less acceleration, slightly greater fuel economy, and slightly less revs at the same speed. What are the quantitative measurements on...
  2. Buildable

    Revs STILL Surge!

    I've owned my RC390 for one year now and loved every second of it, so much so that I'm going to keep the bike even after getting my full license. As much as I enjoy the bike its the little imperfections in it that drive me insane! The first things I did to the bike was fix EVERY little rattle...