i have an 893cc blade with 38mm carbs, i notice that the R1 has 40mm carbs, would it be worthwhile switching over regarding power increase, can it be done?

Unless you have done porting, cam, valve work, and significantly increased potential engine power there is no point at all in changing to 2mm larger carbs.

I'm sure it could be done (anythings possible) but they are probably 38mm at the moment for a good reason

so unless you've done some major work to the engine that will require bigger carbs to feed it then you might actually loose power....

ok, i just assumed more fuel equals more power, i guess you need more air to go with it hence a turbo/ supercharger

there isn't a magic way to get more power for next to know cost/work...

unless an engine has a really bad feature that kill its performance (like the port shapes on a pinto head) then you'll need to change more than one thing to see any real gains and even then you always need to re-tune/re-map