[2007-400ex]

My motor is stock and I was thinking of replacing the stock air filter with a K&N and was wondering if I have to get the carb jetted. Also do you have to jet it for a slip on muffler or just when you install a full-exhaust?

Thanks

 

[450RMAN]

U shouldent need to jet it witht he k&N airfilter but i think that u will have to jet it with either a slip on or a full exaust system

 

[tomgodd]

I have an 2007 400ex and I did not jet it for a k&n. but if I ever put an exhaust on it i would go with a full system it would need jetted

 

[jeeping1974]

Just changing the filter will not make enough of a difference to need a rejet. If you swap the muffler for a performance one, I would do a full exahust system as everyone else has said. With that, you will need a rejet kit.

 

[Jbacon]

If you only have a stock motor, most of the power comes from the slip-on part of the exhaust. It's kinda uselesss to have a full. You can save money that way too. But hey it makes a lil more power. Do you ride in dusty/dirty conditions? If so then I would get a UNI air filter. They don't let in as much dirt as the K&N's do. Or you could just put a cover over the K&N, but it costs like $20 more over the UNI.

 

[tomgodd]

I always use a outer wear with my K&N and it never really gets that dirty and I think the K&N cleans easier. BUt I have both a UNI and a K&N and they both work great.

 

[TRX2fiveO]

I agree with the others I wouldn't worry about the jet kit if you are only replacing the filter. If you pput the exhaust on then yes definitely jet it. Using just a slip on muffler with the stock exhaust is good my friend has yashamira muffler,k&n and a jet kit it run really well