re: crf250 service intervals:
One thing sure....if you don't check the oil every hour, you will be finding the mandatory service interval to be about sixty-one minutes.
OK, maybe a bit of an exaggeration, but not by much. Don't imagine the -r is different and the -x uses oil at a high rate. In one ride's time the -x I rode went from plumb full to not showing on the stick......with the stick threaded all the way in!
That's pretty handy.
RE: sound level testing
Those tests vary hugely by equipment used and its use. Last local event tech guys used a preprinted sheet that listed all bikes made and the rpm at which the SPL should be checked.
......they couldn't find my oddball 2000 KDX 200 on that list! It checked @ 94db. Just two weeks before it was 99db checked by the same crew.
RE: con/di and verging:
Those heat'n blue marks are there for some reason other than just plain prettiness?
OK. Now I can say I've seen one.
'The valve seat..' Exhaust I presume? Is one exhaust valve more of a problem than the other? The 'forked rocker' makes me wonder if the valves 'wear' the same. Woods or track? Did it have a rad fan?