172 kit ont a standard Crank?

hi I want to put a 172 kit in my gilera runner sp125 do I need to put a new crank in or would I be able to run the ngf172 kit off the standard crank.prob a stupid question but any advice welcome

 

Depends on the age of the crank and main bearings, and what kind of mileage they've done.

 

bikes done 14000 miles and think its the original crank and bearings bike runs ok at the moment just seems like it should be quickers its completely stock at the moment max out a round 63mph bike starts 1st time every time

 

I'd be looking at why it only does about 63 if i were you first before shelling out for a top end. Thats way too slow for a sp125. My 70cc zip does 62mph clock speed and thats without the gear-up.

 

clock speed says 66-67 so gueseing its more like 62 I know the throttle has a lot of play in it could it be as simple as not getting full throttle?

 

It could be, but equally it could need a new piston and rings, to restore the compression lost due to wear.

 

would you just put in a standard piston and cylinder kit or put in a 172?

 

I'd go for the standard piston and see if that helps matters once you've run it in.

 

ok cheers for the advice gonna get throttle tightened up tomorrow see how that goes the gonna prob go for a standard piston and crank be one of the last stock ones on the road lol