With a 52mm stroker it would give you a 95cc engine,
48mm piston X 52mm Stroke=95cc. And to give it that extra fuel that it will want you can get a xr70 carb which is 17mm and a 70 intake to match. This will have your bike flat out hauling and still look stock.
Take your stock jug and have it bored and honed out to match a 51mm Pstn kit. Than have a 52mm crank installed and make sure you have a trimmed skirt pstn to match the crank. Throw a xr70 head w/larbger valves on and have ported if you like. This is a sleeper we run and you cannot tell at all. Its a very controlled power that you can really rock on .
The most important thing we have noticed when we build the motor is it is more important to have a fast reving motor than a real large cc motor.
We have the above motor with a inner roter kit and the Tak. 3 speed tranny/clutch kit that takes all the weight off the crank and lets it twist like a 2-stroke, and i really mean like a 2-stroke. The inner rotor you can't see but when you add the clutch it gets costly and you can see it for sure
The above motor is = 106cc
add just the inner rotor and you got a sleeper that you will be able to really control and kick some ass on.
for a clutch u can get a kitaco one (the beefed up ct style) and eff it up a bit, put hack mrks n the case and get it all dirty, be like YUP just picked up this bad boy at aold honda shop, things a 1975 ct 70, it hauls tho 8) and everyone will laugh at u then u will start her up and hold it pinned and beat them adn then u can laugh at them :lol:
Here is what I've done and seen we use a high compression 75cc piston on a jug that sais 49cc pull your crank out have a machinest install a longer rod on your crank but in a differant location on the crank so your rod doesn't puch threw your head this gives you a mild stoker that revs like a mad dog and gives you that stock cheater look .
PS. trust me some one will question you on this because this motor will pull like a 88cc