350x big bore question

[mattpiston]

okay i have 3 350x atcs and one is stock other i built the motor last year...but now i want the other one built for riding at the sand dunes. should i go with a 393 big bore kit and a stroker kit? or just a stroker kit and stock bore? or a 425 big bore kit? also the 425 requires case boring is that something i can do myself by spliting the case and using a good rotery file? im looking for a build that has loads of torque for climbing but i want it to be fast to race also. I am using stage 2 race grind cam also. and of corse new carb. what combination would be the best? Thanks matt.

[The Goat]

I'll only say that a 37mm fcr is going to be your best bet for carbs. Let the gurus come in and talk engines.

Get portwork.

[SWIGIN]

a 460 is a good solid motor...89mm bore (xr500) and a powroll crank.

check out my thread in the mad scientist section.

[mattpiston]

are you able to kick start the 460? and how reliable is it at 100 degrees outside riding? im kinda leaning towards the 393 and stroker i think it will be more reliable wouldnt you think? thanks for the imput guys

[SWIGIN]

starts fine but you will need to add another oil cooler with ether.

the 89mm is nice since you can use off the shelf xr500 pistons...no special high dollar parts

[mattpiston]

will the stock transmission crank and rod hold up to the 89mm piston?

[SWIGIN]

as well as anything else.....but your not useing a stock rod and crank for a 460.

if you just want to do the big bore dont exspect near the power....big bores make power up high.

[mattpiston]

well im going to stroke it for sure but im not sure what i will do with the cylinder yet. i may just put a high comp piston and cam for now and then when the oil field picks back up then maybe go big!!! what is your oppinion on duel exhaust. will that hurt anything power wise? i fabricated a bigger header and i got to thinking that duel would look cool.

[The Goat]

sir with your previous post. you just started a hailstorm.

before anyone comes in here...

I spoke with Tom at TC racing about dual exhaust...it presents the same flow as a highflow exhaust system. going back into a single as quickly as possible DOES NOT increase torque or hp

according to him, flow will always be restricted by your motor...you can't make these things breathe too freely just by putting a dual on her.

[mattpiston]

i see well i just figured it would look bad ass to have it dueled and i was just making sure that the exhaust didnt require being connected. the way i see it when the connect one helps pull the exhaust out thats why i was woundering if it will hurt any low end torque or high end. well my plan for tonight when i get home is to pull my engine out and split it open to get to my crank....i have 2 good reliable ones this one here is just my backup engine...now i just figure i will try to race at the dunes with it a lil bit....i mean the stock holds its own pretty well but allways room for power lol! thanks guys for your input.

[SWIGIN]

heres a 2'' pipe i made for my RX....you wont need anything bigger

notice how it hugs the head/cly...i shorten the header but i doubt you can if this is for a trike.

[The Goat]

that thing has to be loud swigin

[SWIGIN]

nope, not at all

its deep but not what i would call loud (cobra or any old school megaphone pipe is what i call loud)

[SWIGIN]

heres a dirty pic of the rest of the system.....its 2'' all the way back, even the core but the turn down might be slightly bigger....cant remember

last pic shows the turn down....you would be amazed at the sound waves the ground will soak up.

beleive it or not the core in this pipe is twice the length of a cobra/suppertrapp/DG megaphone

[The Goat]

na...I have a 4 inch turndown on an xb....I know what happens. deeper with less cracking or popping.

now at 7k on the tach and I pass you on the interstate....cover your ears.