shlbyntro

so i was going through my shop manual the other day and started noticing that there were 2 different lines of kawasaki 650's theres a JF650 line of engines which were primarily used in x2's and then theres a line of JS650 engines. (JF and JS refering to the first 2 digits in the engine i.d. #) theres different tolerances i noticed for the 2 engines. some JF specs are tigher than JS specs and some are looser.

anyone know what the differences between these 2 engines are? performance/reliability/builbability wise?

building a JF650 for my js440 standup. is y im wondering....