Will it make a difference??

[ride red]

I have a 2000 400EX with a WB racing cam, JE 11:1 piston, and WB rev box. I have a K&N air filter on it too with a Yoshi slip on but have been thinking about getting a full system, like a curtis sparks. I do alot of drag racing and I was wandering if putting a full system would make a big difference over the yoshi slip on or should I put my money in somethin else, like a carb or somethin. Thanks for any advice!!

[airheadedduner]

A full system will help. I would look into a 416 kit before a carb though. As far as a carb I would go with a Keihin 39 FCR, the 41 may be too much for your engine as it is even if you had a 416 kit already. Check with sparks to see if thier timing key is compatible with your rev box, those things are cheep power.

[ride red]

How much am I looking at for a carb? Also to put the 416 kit in and I already put a 11:1 in but didn't bore would the 416 make a noticable difference.

[Nausty]

carb is 450 if I remember right from sparks

[Wheelie]

There is no point in spending $200 to buy a new piston and bore your quad to a 416 when you already have a 11:1 piston installed. The power gain would not be worth it.

I say go with the FCR 39mm carb, or have the flywheel lightened. The latter of the two won't gain you any hp, but it will improve acceleration.

[airheadedduner]

But when you start to go to a bigger carb without at least a 416 you run into jetting problems on the bottom end. Now that I think about it you should be able to have a free flow mod done to your carb for a lot cheaper then an aftermarket one.

[ride red]

What can I do to my stock carb to make it flow better and if there is anything I can buy how much would I be lookin at?

Remove the choke and put in #42 pilot jet- you will notice a difference, and it's free!
Search for (choke removal) there are some good threads on it. After that how fast do you want to spend?

[ride red]

On money, I don't really want to spend awhole lot, but it's not really a promblem. I thought about gettin my head port and polished but I don't know anything on that to much, how much does that cost and is it worth it.

[airheadedduner]

Port and polish does help but I can't give you exact numbers. But for the money it cost to port a thumper it is not worth it to me. If you decide to try porting it yourself don't polish the intake ports smooth, it needs to be a little rough. The exhuast side can be polished till it shines As for 2slow's #42 pilot that may not work. Removeing the choke would help but a #42 pilot may not be the proper pilot for your bike, he is running different set up then you. Taking the time to get the prper jetting specs is most of the battle in getting the most out of your machine. You could cut some holes in the airbox lid or remove it for more flow.