Hi, I did a re-build a little while ago, the cause of the re-build was that the bearing on the clutch side of the secondary shaft wore out, then it fell out and of course the shaft flogged out the cases, have a couple of spare motors, used an old bottom cases spare I had and the secondary shaft from it to fix the old girl up. As most Aussie 13 owners will know, and I guess others, the cost of parts, if you can get them is rather scarey, anyway the barrels were pretty good, did a hone and new rings, big end and main bearing and of course secondary shaft bearings. I had the head checked and new valves put in, exhaust valves are hard to find, but anyway silly me thought the valve stem seals would be ok, never assume that, another reason I never changed them was because every bike shop I contacted wanted $20 each, and at the time, after getting all the other parts from either Germany of England I was a tad broke. Anyway I got a complete set from e-bay for $45, and because it our Labor day long weekend, I decided to pull the head and change them, also got a whole new 6 into 1 exhaust system to put on at the same time. I changed the seals yesterday, so the head and the other new bits will go on today or tomorrow, So anyway, just a bit of news on my old girl, she keeps on going, now if I can stop the blue smoke when I give her a gut full of throttle I'll be really happy, cheers Pete