Big Bore Kit for 300ex

[Daniel300ex]

Hey guys...

Where's the best site (other than ebay) to get a 330 big bore kit for my 2001? I would prefer not to have to machine the head out if possible and just stick with the 74mm piston.... i think that's what's in it... If I have too, thats fine. If I put in a big bore kit do I have to upgrade the cam and cam chain as well?

Also, if anyone knows where I can find a used (but in good shape) 400ex carb for sale... let me know.

Thankx for your help!

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2001 300ex
Slight mods, mostly cosmetic...

[Daniel300ex]

Decided i want to go .80 over on the bore and get the oil cooler.. Im going to contact FST and see what they can do for me... if I do th 330 kit should I get stage 2 web cams or stage 3?

[m0t0xk1d]

you said you want to get a big bore kit but stay with the 74mm piston. ok well a big bore kit is a bigger piston unless you stroke and then it would be a stroker kit. just verifying that with you. and i think .80 is 76 mm piston so yes then you will have a bigger piston

[bwamos]

Aye.. you also won't have 330 unless you stroke it as well. But the .80 over is a good size. Unless you meant 0.080 over than it's still pretty much a stock piston.

A 330cc big bore is an 0.240" overbore. aka +6mm or an 80mm piston.

To get 330cc with a 74mm piston youd need a +11mm stroke which isn't possible as far as I know. I'm pretty sure there would be clearance issues. You can do both a stroke+bigbore to get a 330 as well. There's lots of combinations depending on what you're wanting out of the power curve.

Another good setup is the good old tried and true, true 300cc. (The stocker is 282cc.)

[bwamos]

Originally posted by Daniel300ex
if I do th 330 kit should I get stage 2 web cams or stage 3?

I'd talk to whoever is doing the engine job for you (FST etc), and get what works best with the build.

I got a custom MX grind cam from FST when I had him do my engine build many years ago.