I,ve just done the piston and rings on my 07 250f. Second time in a week. First time it smoked like f**k. So got a new oil ring, as its the vertex piston, with the 3 piece set up. Put it all back and now it smokes again, not as much, cos last time it smoked loads. start it up and its fine, then after maybe a minute or two it starts smoking, just slightly though. Its got my head in bits. I haven't been out on it yet to run it in, just started it 3 times for a few minutes to see if it would stop and was the same. wtf?? Also snapped the spark plug in the head but thats another story, easy fix, luckily. Should it smoke for a bit when running in?