Hi guys. I just recieved a k&n filter with pre cleaner and im wondering where i should start in terms of main jet ect. I have the full dyno jet kit and will be riding with the air lid off. Also, its winter here and im not sure if the cold temp will affect the jetting in any way.

 

ps. im 400ft above sea level

 

I'd start with the stock jetting and let the plug color guide me. I'd guess that a cpl sizes bigger main will be close tho.
Air flows are not going to change with the K&N but the lid off will change the amont of air flowed.

 

Add a KN filter and you'll be lean. I dont know what the pre filter does to it... Remove the airbox lid and you'll be even leaner. Ride in cold temps and you'll be leaner still. That's 3 strikes against you! Start stock just to be sure and work up in jet size until it runs right. First, obviously, you need it to idle so it might not be a bad idea to go ahead and stick a richer pilot jet in. Then work on the main jet. And then the needle. Then come back to the pilot after the main and needle are right.

If you put a richer main it and still cant get it to rev out all the way, adjust the needle clip one notch down and try that. Then go another notch if that don't help. If that still doesnt help, go another main jet size and put the clip back in the needle to the stock notch and start over. Keep going until your needle clip is in the middle somewhere and you have good power and the spark plug looks like coffee with cream. Keep in mind if the engine is not good n warm when doing all this, you'll be wasting your time.