ok.. i'm not the smartest person when it comes to modifying a fourwheeler but i want to bore my EX to something new to get some power, but however i want it to be below 426.. is there any company that makes a kit for that.. now i've seen these 406 and they state No Sleeve.. does that mean u just install the piston without a sleeve??? sounds a little dangerous to me... any help would be great

 

The September 4WA did a special on a Baja 416ex. You can get that from White Bros I think. I'm pretty sure and it has more top end than the 440. Plus it has 40 hp.

 

you can get pistons right from wiseco 86mm=406,87mm=416,88mm(max for stock sleeve)=426.the 87&88 uses a different head gasket the xr 400 is the same pistons and gaskets -buy your parts and tell the shop boring it what to bore it to.i have a 426 and it works great-smaller pistons rev higher than 440,s but have a little less torque.if you do get a 425/88mm and something ever happens you have to resleeve but that's no biggy it not that exspensive and chances are nothin will ever happen-it's a HONDA. I've beat the snot out of mine for 2 years now and it runs mint my compression hasn't dropped a bit(217psi-i have many other mods though)

 

You can do many of the mods yourself as I did. I just found a good machine shop to do the boring and valve work...
Another place to look at for info would be
www.sparksracing.com

I havent used any of there services or parts but they atleast have some information that might be helpful to you .
later
Chuck
www.trxoutlawz.com