Not that good at maths mate,what do these work out at?

+2 are 428cc.

Im not 100% with hondas mate, im a zxr fellow.
Your +1mm pistons i think are fine, as said they are allowed at the mgp now and bemsee. Other clubs will follow over the next couple of seasons i think, although as it stands still illegal in quite a few. Im guilty too tho, i have a +1mm motor.
I dont see the point of using +2mm pistons.
They will never be legal in f400, only in things like thundersportsgb. So thats why i say if you gonna go down that big bore option you might aswell go for the +3mm piston.Ive seen that gets you well into the 80hp on the dynojet with the v4's

+2's about as big as you can go on the Honda's, at least the V4's.... kinda along your logic... might as well go as big as you can!

Do you have to put liners in with those then?

So far as I understand, no... +2's the largest you can go with boring what's there.

I meant these bigger ones.How do you fit those.

Got me, never heard of anything bigger than a +2... as the guy said, he's a kawi guy... maybe in the CBR400's you can?? Not in the V4's so far as I know.

Dont know mate,he said why.

sorry my mistake... told you im a zxr person!
I meant 433, not 440.
they are +2.5 the ones i meant....

but same difference