i just got a 650sx.
no more yamaha's for now.
i am making the 650sx handling changes right now.
what are the engine mod's you can do in that class ???
the vintage class should be just stocker's ???
no add-ons !!!
i remember when the stock 750 class came out on 92. that was kinda even.
stock oem pipe's only.
a/m reeds, stock carb's only, but could put different jets in, ride plate's, intake grate's, prop's, and timing advance plate's all good to get wet.
that was it.
a lot of people would jack up the clyinder with thick base's gasket too.
is the yamaha 650 sj sn racing in that class too ???
does the apba run that class, or is it up to the race promoter what can be done to the ski, and if any tech would be done to see if anybody is cheating.
good luck
gorilla