I just got a 400ex, and was wondering if the White Brothers kit(pipe,rev box, and filter for $400) really make a big difference in power?

Or should i go with a 440 kit? What is the price of this.
Thanks

 

If you really want to gain power just buy a basic k&n filter and a WB slip on pipe. DONT BUY THE K&N POWERKIT IT IS A WASTE OF MONEY. Go to the shop and just buy like a 168 or so jet for your carb that should probably do. This will probably be the cheapest way to go in my mind. If not then look around for a deal. those wb packages dont seem to appealling to me but i guess it is personal oppinion. You also have to think about wether or not you are going to mod the enine at all? If you are then you will be best off buying a pipe that will work well with your engine mods. Just my 2 cents...

 

I agree with prang11 on staying away from the power kit. Alot of people seem to have problems with the rev box in the cold and you live in Michigan ,also the engine loses power after the stock rpm cutout. As far as a jet goes I think 168 may be a little much for a pipe and filter given your location. When mine just had a pipe/filter I had a 158,so for a safe start I would go 162/165 and work down.Doing these mods will help and make a good difference. Now,you do not have to get a 440 kit to make strong power.Alot of people I have talked to are keeping the stock bore or up to a 416,some 440's all with good results. Doing a high comp. piston and a cam make it a whole new machine. It depends on what you want to spend.I kept the stock bore and am very happy with it, and I think at a reliability standpoint will be better than a 440 in the long run and I can always bore it out a couple more times.
Jim

 

It depends on what you want.
First step, pipe, filter, and jetkit. you need these before moving to engine mods.
Thiers all kinds of mods and ways of going about it.
The first mods will be the cheapest horse power gains and will liven it up quite a bit.
All riders are different and after you get these mods on you will then have a better idea of what you want.
Go to www.dirtwheelsmag.com, they have a hop up secrets article that lets three different shops have the 400ex and give them 200,500, and 800 budgets, pretty interesting.
Alot of poeple such as white brothers have thier own jetting systems, if you go with these systems, it only makes sense to use thier jetting. But as far as just bumping up the main, well do that and it will cost you $3, then spend $40 on a jet kit and I personaly garrenty you will rejet every bike you ever own.

And for the guys who are going to bash me about jet kits, the after market needle wich is graet allows a bump up in air/fuel mixture, inturn will end up with the same size or smaller jetting than stalk, it is a full make over on your mid range, not to mention good smooth power through out, and gives an over all better throtle response.