Our recent experience with our project CR125 told us that rebuilding an engine can be a very expensive business. When we found out that the Pursang engine was a 370 we thought twice about rebuilding it as it required everything, including two sets of coils and the electrics. Fortunately, lady luck was about to smile.

Flicking through T+MX we noticed an ad for a 250 Pursang with a spare 125 engine thrown in. We gave the guy a call and he said the bike was gone, but he had the buyers mobile number - we gave the buyer a call and arranged to buy the rebuilt 125 for £200...

	The engine we bought looks in great condition and comes with a carb, electrics (minus coil) and pipe etc...Most pursang engines are interchangeable with other years as the centre case castings didn't change much. The only problem was that this is from a MK7, which has a right hand gearchange, our frame is a MK10 - designed for left hand gearchange...
	Hmmm, this is where the gearchange should be! We will have to move the brake pedal to this side or the gearchange. The gearchange can be moved by using a later left hand crank case and shaft, but this means splitting the cases (and finding a 125 crankcase), so its easier to bodge up the brake.
	A knock on effect of the MK7 engine in the MK10 frame is that the mounting point for the exhaust is different. Our frame has the brake lever pivot point where the exhaust should bolt on - we'll have to make up a small bracket
	No problems with the carb to airbox rubber, it fits just fine.
	We managed to get a new filter, but couldn't source the internal cage so we decided to make our own out of a coffee tin that just happened to be the right size...
	We basically trimmed away most of the tin, just leaving enough to resist the springs that hold the filter in place - not tidy but it does work...
	And here it is in place, note badly applied filter oil!