ok dean ,how fast were you going?did it stop quickly?did it slow down before it stopped?did the back wheel lock for a second before it stopped?have you tried to kickstart it yourself and felt the resistance of the kickstart lever on your foot?it may well have broken the drive belt for the oil and water pump these are a common fault with the 50cc and 125/180 runners alike.an engine rebulid will not guarantee an engine against future problems.what happened last time it went wrong.take the black round plug out from just under the kickstart to the left of it and shine a torch in there,is there any broken transmission belt pieces in there like small rubber blocks laying about and maybe some fluffy material?also the oil pump drive belt is in there behind the back of the variator.
adam bike doctor, March 2010