400ex going to 440kit

[YOGILUNA]

i have 400ex with a full hmf pipe and a curtis sparks cam and i wan't to know if a convert my 400 to 440 with ported polished head how much bike would i gain.

[krt400ex]

alot. u should see around 40 hp. u will get big gains from a stroker kit

[-copyguy-]

which way were you lookin at getting to a 440? Bore only or take it to a 416 and stroke it 4mm?

When I do mine (someday) it'll be a stroker.

[AdamEX]

i have a question about boring. this might sound stupid but at some shops they say that header pipes don't make a difference. but if i am going to big bore to a 440 i will definately need a header right?

[AdamEX]

i have a question about boring. this might sound stupid but at some shops they say that header pipes don't make a difference. but if i am going to big bore to a 440 i will definately need a header right?

[PismoLocal]

An after market header will make a difference, on a 440 an aftermarket header would make most likely more of a difference than on a stock bore. You don't have to have a header on a 440 but it would seem logical to get an aftermarket full system exhaust before you start talking about spending mucho dinero increasing your displacement.

[Nick shupe]

If you're going to do the 440 kit I would get a 39mm FCR carb for it that's what I have on my 440ex and it makes a big diff. in power in fact you'll never get all of the power out of the 440 unless you do it and I would get a header pipe for it to every little bit helps on the 400's. That's just me though

[AdamEX]

i didn't plan on boring it before the header i just wanted to know if it made a big difference on a 400 with just intake and exhaust. but i eill definately be putting one on. thanks guys