OOOHHHHHH!! I love being the guinea pig for cool ideas!!!
have you ever thought about using "engine ice" in the coolant system?? i tryed it,as i had cooling problems with my kx360 big bore and it solved my problem...
i take my jetting always on the safer side with a smart little bit to rich and i never blown up an engine in my live . actual k5 main jet 162 , but this is for mx only in my needs!
for long highsppeed distance like you did in the desert, i think 175 or bigger main!! in similar engines can be needed diferent jettings . caused of riders attitude,is the right gas in the tank?? which carb or exhaust is installed, which kind of air filter is used. i found out, that twin-air-filters have more airflow than stock-airfilters for example..
important: always take a look at the spark plug!!...
if high-octane-racefuel is used,needs complete different jetting than the 98 octane-super plus gas.
my ´97 kx250 has a 172 in it and was running perfekt in all conditions with dep-exhaust and twin-airfilter . the new owner was falling in love after first ride
in my gasgas ec300 that i had a few yours ago, i ran 178 for mx and a 190 main was needed for street use and highspeed-offroad .
if the engine is jetted right, offers the fuel a little bit cooling extra . if its to lean jetted its heating up more and also to less lubrication,caused of the to small main jet !! and if you ignore to long the lean motorsound its heating up to much and....kaboom... .
and here is my cool guinea-pig ... yo