I recently bought a CBR 600, it runs great from idle to around 8k rpm, it has a Yoshi rs-3 pipe on it so I figured the previous owner didn't have the carbs jetted. I want to re-jet my carbs but I don't know what jet/needle set would work best with my setup. i don't want to take it to a shop so they can charge me for something i can do on my own with some help with info.Anyone have any advice on what set I need? Thanks in advance.

 

You will probably have better luck in the F4 section, but I would not start changing the jetting sizes before pulling & thoroughly cleaning the carbs and checking the jets & needles while you have them apart. It's more likely a dirty or clogged main jet, or other fuel delivery problem rather than a jet size issue.

If the only modification to the bike is the exhaust it should run fine on stock main jets, or at most 1 to 2 sizes larger depending on your altitude. Clean the carbs, check the jet sizes, check or replace the fuel filter, and make sure the pump is working correctly first.

 

Yeah do all that stuff first then after that pull the plugs. Sooty black= running rich, whiteish ashy looking=running lean, paper brown tanish color= just right. I had a k&n filter with yoshi rs3 and it ran perfect without any jet size changes.

 

Oh, also check for a clogged fuel filter. Run it without a fuel filter for couple miles to see if it opens it up and runs any better. Its happened to me before.