Any good engineering company should be able to bore the carbs, but I seem to recall the MC28 carbs will only go to about 33.5mm maximum before you break through the casing.

MC28 carbs are easier to bore than MC21, as the venturi are round.

You'd be much better off using RS PJ38's or PWK's if you want to go for big carbs. The inlet manifolds are hard to source though.
_________________
Andy.
NSR-WORLD.COM

Please keep all responses to Forum posts on the Forum so that others may benefit.

Please DO NOT PM me for technical advice. My time is precious, and you will probably receive a faster response on the Forum anyway.

Check us out on Facebook! Please "like" our page!