416 pistion stg 2 hotcam

[Grant Casey]

I am considering rebuilding my 400ex and im gona put a 10.8:1 416 pistion amd a stage 2 hotcam. all use 400ex that have these same mods how did it make your 400ex go good in the mid top end or watever.
soon after that a full system lrd exhaust carb and so fourth.

cheers grant

[jsmith2232]

I built my motor as listed in my sig last spring and it runs very strong. Pulls wheelies sitting down in 5th, I made it to silver lake dunes once this year and never got beat by another 400 and even beat a fair amount of 450's. Very reliable, torqey and pulls hard all the way thru the gears.

[khen]

I had a 11:1 compression 416 with the 450R carb, HC stg 2 cam, high rev CDI, XR400 gaskets and straight through exhaust and it was a night and day difference from stock.

To give you an idea, a similar build brought the EX from the stock 26hp to 43hp on the dyno.

Unfortunatly, I overheated it in the dunes and pulled the stock head studs. I rebuilt it to a lower compression 406 and the power isn't nearly as good as it was with the higher compression 416.

With the stg 2 I would highly recommend getting a higher rev CDI. A 450R carb takes a bit of work to install, but it is well worth it as well. I would also recommend the HD head studs while you are in there.

If you ride really hard, you might consider running a race/premium gas mix. Mine started pinging before pulling the studs.

[brapbrap13]

full lrd, 416 kit, stage 2 hot cam. exactly wat i have and i love it.

[450Rchaser]

I think that is the best way to go w/ a 400 ex.