I just recently re-did my 400ex with a Wiseco 11:1 440ex piston, a HotCams Stage 2. I have a K&N air filter, and a White Bros Slip on pipe. Still running the stock carb. I race a Z400 with a jet kit and full pipe, and i only beat him by a bike or two. Take in mind i just put it back togther and have to adjust the valves and get the jetting right. I was wondering if a Rev Box or a Header pipe would make much of a difference. Also how will I stand up against the Pred. and Raptor in the dunes. thanks for the help.

 

In my opinion, I say get a complete exhaust before a rev box. If your head hasn't been ported the 11:1 and stage 2 probably won't build power up to 9000rpms. If you can't build power to that speed why run there?

 

..pipe before you get a rev box..sparks X6 pipe....440 with cam pipe,and maybe even carb..will run with or out run a pred...surley it will wax that Z with a pipe..

 

if your not hitting the rev limiter, your not letting it rev high enough. this is the kind of racing i do a lot and i have tried several things. a good full pipe will make a very very big difference too. i gain at a minimum 5 bike lengths with a rev box too though. it will feel like you need to shift, but dont. i realize it is hard on the motor but you will be quicker (when dragging).

 

you might consider getting a 450r carb. thats what I done and i LOVE IT!

I agree with the others... you need a full system now with a race kit installled. I also run a GT Thunder REV box. You dont "gain" anything outof a Rev box, but for my racing it helps on the rpms when Im in between gearing on the track and I can hold that gear a bit longer [img]i/expressions/face-icon-small-wink.gif[/img] Hope this helps some!


Tina

 

Thanks for the help. I have one more quick question.. Do White Bros sell just the header pipe for the 400ex? In all of my catalogs they don't show it.

 

not sure on that , I run a Yoshi. I know that I could on my pipe but not sure on a WB pipe. Alot of pipes you have to buy at once.

 

WB, last time i checked, made 2 headers for their systems. the s-bend and the pro meg headers. the s-bend, i believe will fit on their slip on silencers (and all other slip on silencers too). the pro meg headers (their good line up), won't fit on any slip on silencer. this header was specifically made for their full system silencer. the fmf powerbomb header will fit on your slip on though (and all other slip on silencers). i would just sell that one and get a good full system.