01 400ex carb settings

[NJ400ex01]

I have a 01 400ex with Big Gun Exhaust. I was wondering if anyone knew the carb settings for this setup? I have good top end but the bottom end is just not there. I rode my friends 99 400ex and it had a lot more punch. Any help is appreciated.
Thanks

[Aceman]

What is your jetting at now? Have you put on an aftermarket filter or is the Big Gun your only mod? Do you have a vented airbox or run with no lid?

[NJ400ex01]

I just picked up the quad last week and am not sure of the jetting right now. I know it has been rejetted though. It has a uni foam filter and i am running the stock airbox cover on it.
Thanks

[cals400ex]

it is important to know what temp and altitude your riding in. a general guess would be to run a 155 KEIHIN mainjet in the winter months. in the summer months you will have to go smaller on the mainjet. you could also put in a 42 pilot jet. if the bike seems to be missing when barely on the throttle you may need to move your needle clip to the 4th position.

[cals400ex]

i forgot to mention that keihin jet and dynojets are different. so, a 150 keihin is NOT the same as a 150 dynojet. so, if the bike is rejetted, make sure you know what kind of jets are in it. the keihin jets have a K on the jet. the K almost looks like a star.