Exciter II mechanically:has newer-improved primary clutching, carbs were greatly improved, actually in 88-89, subtle change in the rear skid. Not sure if there was anything done internally on the motor such as port-head changes or not.
Exciter II body: redesigned hood for better air flow to the air box & motor area, different fairing design to accomadat the taller hood design & a straighter standing windshield
Ski stance is the same from 87-93 with the exception of the 93 SX which was around 3" wider.
Beyond that I am not sure. I have a 88 & a 92 sitting here & when comparing parts, they are pretty much the same except for the above mentioned items.
Again, there could be some "tweaks" on the motor & maybe someone with more knowledge on that end will chime in.
Either chassis are fun & nimble especially in deep powder, ya can really throw them around in my opinion.
I have seen claims that there were motor issues with the 570 but from my experiences, it was rock solid. I had a 87 when new, ran it 8500 miles then a 90 for 4500 miles & a 92 that I sold with 5500 miles. Never a motor issue.
Rob
PS: If ya need some Exciter parts, I have quite a few!! LOL
Parting out the 92 & have some leftover stuff from a 90 & a 93 SX.
Note: Not selling the SX motor!!