winter jetting?

you take the bowl off your carb and you will see the main jet right in the middle with a little plastic tab around it. take it out and put a bigger one in, you get them at a stealership or powersports store. they are "small mikuni hex jets" stock is 230
 
with a vitos big bore you are only running a 300 or 310?? that dosent seem right i had a 300 in my stock bore engine with a modified lid and power pros exhaust.
 
..all I know for correct jetting is go up or down 1 size for every 10*

like 0-10, 10-20, 20-30, 30-40....and so on
 
I would get a 30mm or larger if i had your set up. Vito's sells jets for $2.95 a pop...order several...330-340-350-360-370...it depends,....

well i tested it today and its running a tad bit rich. i dont think that will hurt it tho. as long as its not lean?