416 Equals what size piston?

[n811]

I have a 400ex and want to bore it to a 416 what size piston should I buy? how do you do the calculations? where is that info?

[lpmaster]

unfortunately all i know is it is a 87mm piston..

[northwest Texas]

stock bore 397cc 85mm
first over 406cc 86mm
second 416cc 87mm
last possible 426cc 88mm
larger sleeve 426cc 88mm
larger sleeve 440cc 89mm


those are the most common.

If you're wanting the formula to find displacement by knowing the bore and stroke I can get that to you but I don't have it handy.

[n811]

Thanks guys. Thats what i wanted.

[400exrider707]

Originally posted by northwest Texas
stock bore 397cc 85mm
first over 406cc 86mm
second 416cc 87mm
last possible 426cc 88mm
larger sleeve 426cc 88mm
larger sleeve 440cc 89mm


those are the most common.

If you're wanting the formula to find displacement by knowing the bore and stroke I can get that to you but I don't have it handy.

You can get pistons in between most of those. Those are in increments of .040 over, and 89mm is only a 435, 89.5 is a true 440

[northwest Texas]

89mm is only a 435, 89.5 is a true 440 You're right, momentary lapse of brain function. .

Here's the formula for finding displacement.

Radius of BORE squared multiplied by pi multiplied by stroke equals XXXX
XXXX divided by 1,000 equals cubic centimeters

[250X_project]

I have always used Bore X Bore X Stroke X .0007854. That's what I was taught. Or multiply by .7854 then divide the answer by 1000. I think it is more accurate, if you have to use 3.14 for pi.

So yeah, 87mm.