pilot jet , new K&N air filter

[dan5]

As you can see by my sig, I Have a stock 08 400. When I bought it the dealer told me that these bike's come running a little lean, and if I wanted to put a K&N filter on it I should probably re-jet it.

I have also read that if you up the pilot jet to a 42 that the bike will start easier.

So my ? is. If I up the pilot jet , will that be good enough or do I still need to up the main jet. and adjust the f/a screw. At this point and time I just want to put the K&N on.

Also It's hard for me to do a plug run, since I have to drive a min of an hour to go riding, so I'd like to get it as close a possible.

thanx
Dan

[bherriman]

The pilot circuit only plays a role from closed throttle to about 1/2 throttle. So yes adding a filter you will likey need to up the main. You would only need to up it one size from a 148 to a 150. If it were my bike I would go with a 40 pilot. In my opinion a 42 is a little much for a stock bike with just a filter. I run a 40 pilot with a filter and slip on and it starts just fine in cold weather. Under 30 degrees and you have to use half choke for about 5 seconds and it idles perfect.

[3400ben]

Originally posted by bherriman
The pilot circuit only plays a role from closed throttle to about 1/2 throttle. So yes adding a filter you will likey need to up the main. You would only need to up it one size from a 148 to a 150. If it were my bike I would go with a 40 pilot. In my opinion a 42 is a little much for a stock bike with just a filter. I run a 40 pilot with a filter and slip on and it starts just fine in cold weather. Under 30 degrees and you have to use half choke for about 5 seconds and it idles perfect.

Pilot is from closed to 1/8 throttle