400EX engine displacement process

[key4202003]

ok i really dont know the whole deal on boring and displacement. but it seems like there are stages of the engine that go in order. what i mean is:
STOCK,
406=over-stock boar
416=middle boar
426=max boar
440, a 426 with the sleve and high comp piston
does this sound right?? is this the order this engine can be done, and what kit/process has to be included with each boar? also what does each boar make the displacement?? i.e. stock=397cc
thanks for any thoughts,pictures,idea...josh:huh

[2004exrider]

std bore: 397cc or 85mm
402cc- .40 over 86mm
406cc- .60 over 86.5mm
416cc- .80 over 87mm
426cc- .120 over 88mm
440cc- .160 over 89mm

or
440 with an extra 4mm stroke= 460cc
416cc with extra 4mm stroke= 440cc

Little math problem to always remember...
To find cubic centimeters
CC= .7854 x bore sqared (in millimeters) x stroke x number of cylinders. then take that answer and divide it by 1,000 and you will get CC's:)

Jimmy

[Quad Dude]

is that formula just fo a 400ex or anything

[key4202003]

thanks dude that shead some major light:cool: but what mechanical components have to be included with the boar i.e. sleve, high comp piston? isnt .160 over way to much for the cylinder? thanks josh

[NacsMXer]

Originally posted by key4202003
thanks dude that shead some major light:cool: but what mechanical components have to be included with the boar i.e. sleve, high comp piston? isnt .160 over way to much for the cylinder? thanks josh

Just need to be resleeved with a larger sleeve to accomodate the larger bore that's all.

[2004exrider]

that formula is for any piston engine.
any bore up to 426 you can still bore the stock sleeve. after that you have to get a new sleeve. with 440's youll have to get heavy duty head studs to handle the power, different connecting rod, and maybe a stronger crank.

Heres a few other formulas:L
Cubic inch displacement= .7854 x bore squared (inches) x stroke (inches) x # of cylinders

already have cc's

Liters= .7854 x bore squared (in MM's) x stroke (in MM's) x # cylinders then take that answer and divide it by 1,000,000

ps: to go from inches to millimeters divide by .03937
to go from millimeters to inches multiply by .03937

Jimmy

[key4202003]

thanks dude

[mikeboone]

Originally posted by 2004exrider
std bore: 397cc or 85mm
402cc- .40 over 86mm
406cc- .60 over 86.5mm
416cc- .80 over 87mm
426cc- .120 over 88mm
440cc- .160 over 89mm

or
440 with an extra 4mm stroke= 460cc
416cc with extra 4mm stroke= 440cc

Little math problem to always remember...
To find cubic centimeters
CC= .7854 x bore sqared (in millimeters) x stroke x number of cylinders. then take that answer and divide it by 1,000 and you will get CC's:)

Jimmy

The 89mm will only give about 435 cc's. You have ton run a 89.50 piston for true 440 cc's. Good info though

[2004exrider]

woops my mistake, thanks for the correction:)

Jimmy

[mikeboone]

You roughly gain 10 cc's with every 1mm or .40 increase in bore. This applies to the 400ex. You can move the decimal over and find out your stock 400ex is .397 liters; not quite a quart of a liter. If the fuel/air mix was all liquid it would be around 10 oz from BDC to TDC.