de-stroked 200x anyone?

[mullet_boy]

So for the longest time i wanted to stroke my 200x. I just put a new cam in it that has moved the power a fair bit farther up in the rpm range, and that got me to thinking, why not destroke it? If it was destroked and over bored to something near the 200cc mark it would change the power to even farther up in the range and make the power come on more like a modern 450. After some research ive found a couple interesting combos that should work out. Using a cb 125 crank and rod, a trimmed down stock jug with a larger sleeve (cb 750), and one of a few different pistons i could end up around the 200cc mark.

option 1: 49.5 stroke cb 125 crank with 79 suzuki gs 750 piston (wiseco 69mm) = 185.09cc

option 2: same crank with 73 cb750k piston (wiseco 69mm) for the same 185.09cc

option 3: same crank with 73 cb750 piston (JE 68mm) = 179.76cc

Almost all of my info ive gathered is based off of big bore concoctions for cb/xl/tl 125s. which is basically all this would be. The question is what do you guys think about it? worth the change in bore stroke ratio for the loss of the 15 or so cc's? Or if anyone knows of any other pistons besides the ones i listed that are a close fit into a 200x but larger in bore size? (like 70mm and above)

[lndy650]

sounds like an awesome idea. prooobly rev like crazy

[shortline10]

shorter stroke means less tork which would be ok on a short track / flat track set up but for MX and trail riding I dont think you would like it . if you want more RPM do it with the cam and a good port job to the head . MY 02. Cents :beer

[userj8670]

I agree with shortline. It is an awesome idea but it depends on what your going to use this set up for.

[oscarmayer]

So for the longest time i wanted to stroke my 200x.

dude, that's just wrong!!!!! :P

:Bounce :Bounce
:beer

sorry could not help that. after reading hte post on diggie weineer pink and seeing the first line it jsut made be lawl all over!

[oscarmayer]

serious answer:
I've though about this myself I came up with using a 125m rod on the 200x crank and then trimming the jug down the 5.6mm differnece and you can still keep the 200x piston, then toss in a 12:1 weisco shave the head slightly and up it to liek 13.5:1 and it'll rev to hell and you will get a decent powerband. make sure you get a good cam. and yes top notch headporting is a must and good exhaust.

[The Goat]

correct me if I'm wrong here, but isn't a stock 200x engine just a seriously overbored cb125?

or is my history of the engine way off?

One would think swapping the cranks wouldn't be very difficult if the engines are as similar as previously said.

[greenhuman]

serious answer:
I've though about this myself I came up with using a 125m rod on the 200x crank and then trimming the jug down the 5.6mm differnece and you can still keep the 200x piston, then toss in a 12:1 weisco shave the head slightly and up it to liek 13.5:1 and it'll rev to hell and you will get a decent powerband. make sure you get a good cam. and yes top notch headporting is a must and good exhaust.
That 125m rod idea does not shorten the stroke.
I am a firm believer in lengthening the stroke so shortening the stroke is against my religion. Don't destroke it. Get a good crank and you won't have to rev its tits off to go fast.

[AutoXer]

Get a good crank and you won't have to rev its tits off to go fast.
+1 on that

[MagicJames]

Get a good crank and you won't have to rev its tits off to go fast.
+1 on that

+2

Or just buy a bigger trike, IE; 250r or 350x

[WIkid500]

+2

Or just buy a bigger trike, IE; 250r or 350x



Sometimes it's just fun to have the small bike that puts a lot of others to shame.

[oscarmayer]

That 125m rod idea does not shorten the stroke.
I am a firm believer in lengthening the stroke so shortening the stroke is against my religion. Don't destroke it. Get a good crank and you won't have to rev its tits off to go fast.

according to the manual, the 125m rod is 5.6mm shorter than the 200x rod. so wouldn't that destroke it?

[greenhuman]

A shoter rod does not change the stroke of the crank. You could have a rod 4 feet long and the stroke will still be the same.
You have to relocate the crank pin in the crank to change the stroke.

[lndy650]

short strokes are better i like high rpm engines

[mullet_boy]

ok...sorry it took me song long to reply guys, ive been at college all week with no net. Anyways, my reasoning for doing this is as wikid said to put a lot of things to shame that a 200x isnt supposed to. The 125 motor and the 200 motor are basically the same. several small diferences but you can swap a lot of stuff between them. So yes the 200x motor is pretty much a big bore stroker 125 motor. To be completely honest i just want to try this to see how it will act more than anything. I ride mostly flat ground around a 4 acre yard so its pretty much a flat track that i ride for the most part. Although if its to much of a loss in the torque department, i know im not going to like it. Anyone have a good guess how much of a loss id have?

[Bryan Raffa]

I say do it ,, see how it acts

[mullet_boy]

i could always do that...if i dont like it im out a few dollars to resleeve another uncut stock jug and switch back to a stock crank...wich if any one was wondering stock stroke with 69mm bore puts u at around 215 ccs. im sure that cant be bad if the destroked motor doesnt work out lol

[2hundredx]

can u bore a 200x to 69 mm ??

[mullet_boy]

stock? no...i think its something like 67mm stock largest over bore. with a cb 750 sleeve, yes. they dont even make a 69mm piston for a 200x that i know of. have to use either a cb or gs 750 piston to get that high.

[leevarnado]

has any one use the cb750 or gs750 piston in a 200x

[RideRed250R]

are you keeping a eye on wrist pin location? on paper it looks good, but wrist pin location is also key to keeping the piston in check. your also going to run into deck height, sounds like a cool play combo. I am sure it would rev but i think your going to start finding valve train problems pretty easy.