lol...i forgot who said it but 91-92 frame is the simplest to do...just need a 500 intake boot and done...and adjusting the carb isn't to bad...Carl....lol
my build:
500 motor held in with the hybrid mounts by sblt250...
notch for plug, kicker, exhaust
move over chain roller
space rear sprocket
i dont run airbox....waste of space...just made a bracket and run 250r k&n
the bottom motor mount i notched in and re-inforced
ltr 450 rear hubs....gets you 4..110...and wider...
i'm sure i forgot a couple things in there
+1 +2 a-arms...with shock adjustment for those special days...lol
+2 swinger...more than you ever need for 165lb rider
olin front shocks...pep rear...all with rezzies
and i have my weight around 330 dry
and i'll never run a 500 frame again
but when i had the 500 motor in the 400ex frame....i miss that....a lot...was set all MX