110cc crank into 140cc

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jamie17

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im just wondering if anyones heard of putting a 110cc crank
into a 140cc, because ive heard that it stroks it???
 
um.... i dont see it happening in a hurry...

first up, the cranks are completely different. clutch mounting?

and i have the feeling that the 110 has a shorter stroke than the 140...
 
yer the stroke is shorter. but i was just wondreing if anyones heard of it.
 
It's called "De-stroking" ... Drag racers do it to build a super reliable race engine cheaply ... IE You can de-stroke a 454 Chev down to 378 cui or smaller to end up with a physically strong , high revving , tall deck , long rod , big bore engine that has bigger ports and valves than a more fragile mega buck stroked up small block Chev ...

A 140 bore with a 110 crank (55 mm bore x 49.5 mm stroke) makes a 117.6 cc engine ... You'd more than likely need to fit a longer rod onto the 110 crank to get the piston crown back to level with the top of the cylinder and you'd need to use a high dome piston to get enough compression with a BVH head's bigger combustion chamber ... Theoretically you'd end up with a high revving big valve 118 motor that lacks bottom end torque ... You'd have to get a crank out of a start in gear 107/110 ... some of the 3 valve 107's were start in gear as used in SDG bikes ...
 

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