its the sound of air being forced back out of the inlet tract, normally there would be reeds in there and the motor would be turning much faster...so seating the reeds and no blowback
any race bike or high peformance engine, from all manufacturers would be devoid of this groove, the only bike i saw it on was a later model DTR, not sure about the DTRE but the numbers on the casting will tell the tale
the squish band is the band around the combustion area that has a very small gap between the piston and the cylinder head...when the piston is at TDC, some of them have this convoluted groove in them (i know not why) the best one to go for is the one without this groove IMO
in the past i have rounded off the hexagon on the bowl because i used open ended or 12 point ring spanners...i learned my lesson and now i would use a 6 sided socket commonly found with 1/4" drive
yeah i'm thinking of the explosion risk, what if there were a spark inside...I figured rightly or wrongly that something that couldnt be ignited with a match...ie not vapourising...would be safer, I would be concered with using thinners unless it passed the lighted match test but hey I'm no expert
so how is the petcock fixed to the tank?
pehaps for safetys sake stick with water (de ionised) and then rinse out and shake some WD40 about in there to prevent rusting?
not sure about the petcock...do you mean to remove it from the tank or to strip the thing down?
also not sure about using water in the tank, how about using fish tank gravel and paraffin (kerosene) or WD40? I appreciate that you wouldnt want to use something too volatile but you can toss a lighted match into a container of kerosene and it will extinguish it wont it?...waddya think?
i've never had to do this kind of work myself but if i were to go down this route i would prbably not use anything that would ignite by a lighted match............how volatile would laquer thinner be?...take care!