www.zxrworld.co.uk

right hopefully someone can help me out on this

i race a zxr 400 in club racing and the tunning limit allowes us to bore the barrels out to manifacture tollerances

i read up in the zxr400 manual that it is a 0.5mm over bore is what kawasaki allow but that was back when the bike was first built , since then kawasaki have brought out a 1mm overbore piston .

what i would like to know is now the 1mm piston is about dose that mean kawasaki have set the manifacture tollerances higher ?

many thanks

tez

Kawasaki have not (as far as I'm aware) started manufacturing +1mm pistons. Therefore they have not changed tollerances for oversize pistons.

However, you can now get +1mm pistons. Bemsee changes their rules from manufactureres oversize (ZXR being +.5mm, FZR being +1mm and Honda's being none), to 2% tolerance for repair of bores. This enabled up to +1mm for all makes, and stopped the Honda peeps moaning because they felt the FZR's had an advantage.

If your club rules are manufacturers oversize, then it's +.5mm.

Ballsout Racing wrote:and stopped the Honda peeps moaning because they felt the FZR's had an advantage.

they should have bought a proper bike that you can overbore and that isn't ridiculously difficult to tune then.