Is this crazy?

[Dirtcrasher]

A 200CC piston is about 65MM, so 1MM oversize is 1/65th larger. I still don't think 1mm increases displacement as much as you guys think. I could be wrong, but I'd really like to see the actual formula. Can anyone post it up??


Is the crank stroke on a 200 longer than the 185?

Take for instance the 85 vs 86 200X motor. They both end up about 200CC but they have different bores and strokes.

I know bore x stroke has a place in the equation but IDK how the heck to figure it out.....

Somebody must know?????????????

[trizilla]

i dont know the exact formula either. here's what i do know. mainly the only difference between the 185 and the 200 is bore size. not stroke. i believe the carbs are different also. obviously the 200 being slightly larger. as far as the 85 and 86 200x are concerned, i am almost sure that bore size on both are the same its the stroke that changed. 85 is 57.8mm stroke and 86 is 60mm stroke. stock 85 is about 192cc and i think stock 86 is 199cc. im not 100% sure but could the formula be bore x bore x stroke x # of cyl's?
thought i'd edit this, i think that formula may be for cu. in. displacment not cc's.

[84honda200s]

the carbs very from model to model. im pretty sure most of the 185 and 200 motors use the same carb size. with the exception of the 200x.



here is the formula... well one way to figure it out. Bore x bore x stroke x .0031416 divided by 4


dc bud... trizilla is dead on about the 85 and 86 2oox. the actual displacement of the 2 are totally different.




ooo yea and when you bore 3mm over it does help the performance aspect of the motor a little bit. not a ton but it does wake it up a bit. in my opinion there really isnt one great mod but if you do allot of small mods they all add up to get ya some nice power. ive bin there with both a 185 cylinder, and a 200 cylinder.

[TravEX]

Pi X Rsquared x hgt

185 displacement is: Pi x 992.25 x 57.8= 180.176 cc

67mm bore displacement is: Pi x 1122.25 x 57.8= 203.782 cc

200 displacement is : Pi x 1056.25 x 57.8 = 191.798

You have to move the decimal 3 digits to the left for cc using that formula.

[TravEX]

here is the formula... well one way to figure it out. Bore x bore x stroke x .0031416 divided by 4

It's radius squared, so 1/2 the bore times 1/2 the bore. Yes if you use Pi as .00314159 it will come out correctly instead of moving the decimal after the calculation.

[bmxpsyco04]

Thanks for the great tech. info. I had ordered a 67mm wiseco but i'm gonna sell that right away (payed about $110 shipped, cam w/ rings n pin) and I already bought a 65mm wiseco for about $95 shipped. I'll get my 185 bored to fit the 65mm. Then I can put my bike back together! prolly won't work lol, has had the wiring ripped off for over a year, so i'm sure there will be more questions.