The reason for a “kleen air modification” is to stop over-flow oil from getting into the air box and eventually getting into the throttle bodies in the event of a tip-over or from wheelies. It also can help with popping on deceleration with aftermarket exhausts. Since I had my bike torn down to replace the air filter I figured I would get in and do it also taking a few pictures.
I connected the crankcase breather to the reed valves which is supposed to promote more HP due to increased exhaust scavenging from the pressurised air going through the system that the kleen valve used.
I also cleaned all the old dirty air / oil out of the air box lid too so it is nice and clean ready for the new filter, and no more oil due to the mod!
This how to should be the same for 2003 – 2006 CBR600RR however there may be some differences so this is strictly for the 2003 CBR600RR without the SMOG system that I believe the CA spec bikes have.
Tee Connector (I got a 16mm one)
2 x Vacuum Caps (I believe it is 5/8″)
Phillips Head Screwdriver
1. Remove Plastics
I removed the seat, top bolt in the mid fairings / ram air covers. This allows you to then remove the tank cover as well without having to remove the whole mid fairing.
2. Lift Tank
I removed the two bolts for the tank then lifted it slightly and removed the hoses underneath. I then propped the tank up with a snap strap running to the tail of the bike.
3. ECU / Wiring / Fuel Rail
You then need to remove the ECU/ECM and unclip the wiring and move it out of the way to be able to remove the rest of the airbox. You will also need to remove the fuel rail hoses from each end too, remember to be careful as some fuel may leak out so have some rags handy. Undo the 10 screws from the air box lid to remove it and this will expose the air filter. Remove the 3 screws and pull out the air filter. These screws stay in the plastic edging of the air filter.
4. Velocity Stacks
Remove the 6 screws holding in the velocity stacks then you should be able to lift the bottom of the air box out. There is hoses connected underneath the front and on the right hand side which you need to disconnect too (circled in red).
4. Remove PAIR Solenoid and Plumbing
Remove all the plumbing for the reed valves / PAIR system and the hose from the crankcase breather (circled in red).
5. Kleen Air Mod
Use the tee piece and connect the reed valve hoses to each side. Cut a piece of hose for the crankcase breather and connected it to the bottom of the tee. Cap the two holes on the bottom of the air box where you removed the previous hoses (front and side). I didn’t have vacuum caps however had some rubber feet for chair legs laying around and were the perfect size.
I completely cleaned the inside of the airbox lid and also the throttle bodies a bit before I reinstalled everything however installation is simply the reverse. You will have one plug left over that previously connected to the PAIR solenoid valve. Just tape it up as it isn’t needed anymore. Reinstall the plastics and you’re done!
I wont be held responsible for any issues if you decide to do this mod or any failed emissions tests.