340ex

[TRX-330]

ok well found out i gotta bore mine so im gunna go 340. how would a 400ex carb run good with the 340

[cr977]

Originally posted by TRX-330
ok well found out i gotta bore mine so im gunna go 340. how would a 400ex carb run good with the 340

it will not make your bike crazy fast but with proper jetting it can enhance your new bore, without proper jetting it will run worse, you will most likely have to buy some jets to go along with the carb

[honda300EXtreme]

a 400 carb is a great mod for a large bore 300... it will have better throttle response and will pull alot harder....

just remember to rejet it.. it will take a bit of trial and error but you have to get it right for your bike to run to its fullest potential....


also i dont know if you know but sparks sell a 345 kit that comes with a 13:1 piston...

[TRX-330]

well the guy thats doin the machine work is gettin us a deal on a wiseco piston

[TRX-330]

ok i found a 20 over piston for like 80 bucks. was wondering what bikes i would keep up with. i would like too keep up with 400's . id really like the 40 over butt he said to go one step at a time. is it ok to jump from stock bore to a 75 mm bore.

[honda300EXtreme]

wait... a 75mm bore? theres alomost no jump in that at all

stock bore is 74mm if i recall correctly

[TRX-330]

idk what stock bore is butt i know that wiseco says its 1mm over stock bore

[TRX-330]

butt ya that would make stock bore 74 mm

[honda300EXtreme]

ya i though so..

i would go all out.. i would get a 330 kit,,,

fst sells one for 295 and its everything you need.. you would only need someone to install the new sleeve into your jug

[cr977]

there is no deal good enough to make it worth it, unless it is cheap enough to cover a stock bore piston and the small amount it will need to be bored out, you will notice no difference in performance unless you bike is about to blow up. i at least bore it to 330 or 350

[TRX-330]

well i need to have it bored cuz the cylender is ****ed. butt ya im just gunna go with the 40 over piston.

[TRX-330]

Originally posted by cr977
there is no deal good enough to make it worth it, unless it is cheap enough to cover a stock bore piston and the small amount it will need to be bored out, you will notice no difference in performance unless you bike is about to blow up. i at least bore it to 330 or 350

u cant say it wont do anything it will do something. im also having head work done.

[cr977]

Originally posted by TRX-330
u cant say it wont do anything it will do something. im also having head work done.

well, if you cylinder is jacked and you are getting head work done then why not, but i was under the impression this was purly a mod to make your bike faster, im just saying that you have to be a highly skilled rider to notice a 1mm overbore

[honda300EXtreme]

yea with a high compression piston and headwork you will feel a difference...

but if your going on a stock bore you might as well go .80 over

you can go as high as .120 over which is 305cc

[TRX-330]

will any top end gasket set work or do you need one thats made for a 340 piston

[honda300EXtreme]

no you will need a base gasket for a 340 kit.. but all others can be stock...


wait im gettin a little confused what is the displacment of your bike right now ?

[TRX-330]

my bike is all stock. tore apart and waiting to get the piston for the guy to machine it out

[TRX-330]

well had a high comp. piston and has a cam other than that stock. besides a-arms axles and ****.

[honda300EXtreme]

oh,, ok.

[TRX-330]

what pipe's do you guys recommend i should get for a 40 over bore. im thinking about getting a tc shorty, my buddy just got one and i really like it. and i also really like the curtis sparks too.

[honda300EXtreme]

heres you best options..

tc short
sparks
hmf/white brothers header


you wont be dissapointed with any of them

[TRX-330]

ya alot of my friends have hmf i like them too butt, i want something diff. i think im gunna go with the tc or sparks. wish someone had a vid so i could here what they sound like.

[TRX-330]

i dont get it, how much of a bore over is the 330 kit

[honda300EXtreme]

it would be .240 over


or its a 80mm bore

[TRX-330]

oh damn, so whats a 440 for the 400ex's

[Caseys 300ex]

Wait are u getting a 40 over or a 340 kit?

[honda300EXtreme]

Originally posted by TRX-330
oh damn, so whats a 440 for the 400ex's


a 440 is a 87mm bore + 4mm stroke

[honda300EXtreme]

or they also make just an 89mm bore for the 440kit...

[TRX-330]

im only going 40 over, i thought the 40 over ment a 340 my bad. butt will go like 80 over next time i do this. like next summer.

[TRX-330]

what do you guys think i will keep up with. with the 40 over piston and haveing the head ported and polished, and maybe shaved idk if i wanna do that cuz u gotta run special gas.

[honda300EXtreme]

to be honest with just a .40 over bore your still gonna get smoked on all straight stretches by any 400..


as far as the woods racing/track goes.... thats all rider skill

if your thinking about a 330 kit i would od it now.. theres no point rebuilding this summer then doing another rebuild next summer... that just seems like a waste of money to me



but thats my opinion

[TRX-330]

even if i have my head ported polished and shaved ill still get smoked by a 400 on a strait shot

[honda300EXtreme]

yup..

i hope i dont sound like an *** but im just telling you the truth


a FULLY built 330 will run with a piped 400ex... but thats about it...

[TRX-330]

damn people told me a built 330 would smoke a 400 so idk butt you guys prolly know better than them. and i wanna just get my quad runnin so im boreing it 40 over for now maybe winter of next year ill do a 330.

[honda300EXtreme]

depending on certain factors a 330 could beat a 400ex... but not by much


a while back dirtwheels raced a fully built FST 330 against a stock z and it was pretty close.....

[TRX-330]

oh well when i get my 330 in ill be happy ill be able to keep up with the 400's

[2muchquad]

I dont get smoked by 400s with my "300ex":devil:

[honda300EXtreme]

Originally posted by 2muchquad
I dont get smoked by 400s with my "300ex":devil:



well i would sure as hell hope not... with that motor


by the way how does that thing do in a race against a piped 400ex?

[TRX-330]

so what would my bike be considered a 316 or something like that im not sure. and could you guys name like the bore sizes as the 330 and stuff for me.

[TRX-330]

and 2muchquad where u live in ohio pm me man we gotta ride when i get my bike fixed

[2muchquad]

The 330 kit has a 80mm piston.The 299 or "300" kit has a 76mm piston which is 2 mm over stock or .080.Somebody makes a 78mm piston(i think powroll) that would be 313 cc.

[honda300EXtreme]

heres a breakdown... it might help ya out a bit


A stock 300ex is 74mm bore x 65.5mm stroke = 281.56cc's

20 over (.020")= 74.5mm x 65.5mm = 285.38cc
30 over (.030")= 74.75mm x 65.5mm = 287.30cc
40 over (.040")= 75.0mm x 65.5mm = 289.22cc
80 over (.080")= 76.0mm x 65.5mm = 296.99cc
120 over (.120") = 77mm x 65.5mm = 304.85cc
160 over (.160") = 78mm x 65.5mm = 312.82cc
200 over (.200") = 79mm x 65.5mm = 320.90cc
240 over (.240") = 80mm x 65.5mm = 329.07cc


bwamos posted this a while ago ,, so it saved me the time ;)

[TRX-330]

uhh man i sorta get this haha. what would a 40 over piston be called for my quad. thats all i really wanna know.

[Caseys 300ex]

a 290.