Well , the super 550 is an RCH bigger than 99 cc's.The 550 is a 2.165 bore by 1.635 stroke.The super is 2.217 bore by 1.635 stroke giving it 6.3 cubic inchs ,instead of 6.03 of the 550,if I read my micros correctly .:D
What,if any of the parts interchange between the 90 series kart engines...