not trying to be a dick, but mechanics at the dealerships don't know SHIT from a cresent wrench, and a cresent wrench is what they will use to bend you over, they are thieves.
You need to do a good leak down test, not with soapy water, but with plugs and a pressure guage. 6lbs for 6 minutes. if the dealerships idea of fixxing the lean problem is a 420 main jet in a stock stroke CPI piped bike, they are fuckin crazy. there is an underlying problem, not a crank, maybe a crank seal though. or leaky case. your pistons should have a little play side to side, but your crank rods shouldn't really.