I was wanting to know what I can do to get some more power out of my 400. I already have a White Bros. Pro-Meg Exhaust and am waiting on my K&N Power Kit (on backorder). I'd like to have the Big Bore Kit but that's too much money to spend all at once. I would rather modify it one or two parts at a time. The next thing I had planned was a track cam and a White Bros. Rev-Limiter. I would appreciate any suggestions.

 

The first thing any 400 EX owner should do is check to make sure you are getting full throttle. Some members of this board have seen a 30-40 % increase in power by adjusting the throttle correctly.

RoostKing...

p.s. this is not a joke.

 

I've already checked my throttle and It's wide open.

 

I hope you have not installed the pipe yet without the jet kit. i know a couple of people who did that because the pipe manual said it wasn't necessary but now the have holes in the piston. running lean is a VERY bad thing. some people are even weary about changing the filter without rejettnig. if you have read the january issue of DIRTWHEELS they did a test on the white bros. 440 kit and they were very impressed.

Jera '00 400ex

 

You'r on the right track, I went with the w/bros hop up kit. It works great.Cam, filter,piston,rev limiter and pipe. I race local pro classes mostly against banshee's and 250r's. It's very competetive. I win some and lose some.

 

What if someone bought the WB/IMS big bore kit for $285.00? What else would a person need to do if they didn't want to do anything else (i.e. stock pipe)

 

With the IMS big bore kit you would need a cam, rev limiter, aftermarket filter, and definitely a bigger carb.

 

Roostking, you are absolutely right, while perforing a twist throtle conversion, i happened to notice with the cover off the side of the carb, it would only go to about 90% throttle... no wonder jetting it was such a hassle

 

I do not own a 400 ex, but I have seen many instances on this board where a throttle check performed wonders...

HAve a Mery Christmas,

RoostKing...