440 big bore kit questions...

[nightmare311]

Im thinking about getting a 440 big bore kit. I have a 2000 400ex.
questions.....1. just how much does the power increse. 2 is the stock rod ok to run? 3. just some info on places on the net i could look and find stuff about this upgrade..
thanks

[MarkyNark]

Originally posted by nightmare311
Im thinking about getting a 440 big bore kit. I have a 2000 400ex.
questions.....1. just how much does the power increse. 2 is the stock rod ok to run? 3. just some info on places on the net i could look and find stuff about this upgrade..
thanks

A standard 440 will get you to 40hp or so. You can run the stock rod, but they do let loose. I would suggest a carillo rod. I had the stock and ran for 2 years no problems. I put in a carillo rod and then just switch to the stroker rod.

You'll need:

- 440 Kit (440 Sleeve, piston (choose your compression) & Gaset
- Cam
- Carb
- Rod

There's a lot more you can get, but thats what comes to mind.

[kyle440ex]

i would go with the 12.5:1 compression ratio. 440ex's have a habbit of stretching head bolts with much more than that. as for the cam go with a hotcam stage 2, the carb you could leave the stock carb on main jet change to 170 in mine. or if you want a new carb i would definately recommend an FCR carb I just recently put one on mine and man what a difference. best throttle response I've ever had.

[Nausty]

after i put a 440 kit on mine, it was insane the amount of power and response a cdi box added!:eek:

[enduro400rider]

my 440 has good power but if your still on the stock bore i wouldnt go straight to a 440 i would build a good 416, alot of people have good luck with the 416s they run pretty good

[xX-400racer-Xx]

after i put my 440 kit in (w/o porting) i was able to slightly pull ahead of my friend on his piped yfz w/ cam mod. but he does weigh about 90 lbs more than me.