426 Big Bore Kit
+3mm big bore kit, includes JE Pistons complete piston kit and a
Cometic top-end gasket kit. This kit for your 400EX or XR400 gives
a noticeable power increase without a loss in reliability. Available
in 2 different compression ratios. This kit requires your stock
cylinder to be bored and honed – if you’d like us to do that work,
just contact us.