Im wanting to get some info on the best parts to use in a big bore kit for example.. A 426 kit with a weisco piston and stage 2 hot cam VS a JE piston and a web cam.. But then again I also heard that weisco make the JE pistons so there the same just diff. name.. Whats the best set up for both a 440 kit and a 426 kit for a 400ex.. Thanks for the info...

 

Can't tell you what the best setup is, but a lot of people like the 416 as well. Just food for thought.

 

Along with the larger bore and cam set-ups your going to need to run a larger carb to optmize the power output the engine has without holding it back.

 

The 416 is a smarter move then the 426. The 426(88mm) is max for the stock sleeve. If you do the 416(87mm), you can run that till worn then bore to 88mm. If you start at 88 you are buying a sleeve way sooner. I don't know if you can feel a differnce in the 2 sizes without other changes. My 400ex motor is going through this bore right now. I have a stroker crank so it is going from 439.9cc to 450.1cc. I'm curious if i'll notice a change. It'll be a week or 2 before its back in.

 

Well, the 440kit will make more power, but rev lower and slower. My friend got a 430cc kit, it revved fast, with lots of power! make sure you get Hotcam, perferably stage 2, to compliment your piston! good luck.

 

430 kit?? How is that??

Tractor,

What did the stroker crank run you?? What brand is it?? and What size bore are you going to..

 

Go with Sparks 416, you wont be dissapointed

 

what does that run $2000.00??

 

i would go with the 426 kit myself. the 416 kit is the fastest revving big bore available for the 400ex, but the 426 is a close second. the 426 will rev almost as fast, but put out more hp, without sacraficing reliability. sparks can bore your carb so u dont' have to buy a new one, unless your going with the 440 kit, i would reccomend having them bore ur stock carb, it'll save u money, and make life simpler when finding air filters, and mounting them.

 

Becareful before you dive into a stroker crank. It's a hard thing to accomplish and set-up well. Im not sure of the clearences on a EX but you might have to get your cases trenched, depending on how radical your application. By increasing the throw of the piston your also increasing rod angle which can wear the bore and piston faster then a normal set-up. ANybody building a stroker crank will usually add a long rod to help counter act the wearing effect. In my opinion a long rod will be cheeper and get the same effects as a stroker for half the costs.