big bore engine

[johnA]

hello gents is there any way to tell externally if a bike has a big bore engine kit on or do they use the origional block now been told my gpz1100a1 has a cosworth big bore kit on or is the bloke talking out of his arse.
many thanks in advance john

[Pigford]

Depends....

eg: a Z900/1000 could have 1260cc liners fitted, so no external evidence.

Obviously if a proper"big-block" is fitted you can tell as they're very different & usually have a cast monica on the sides.

[london calling]

Often the 1100 cylinders are bored out to give 1170cc,which is 75mm.
The 1089 block can be taken out to 1170 without the need for liners.
Any larger and you need liners and the crankcases opening out.
This would not be visible externally and as Piggy says a big bore block usually has the makers name cast into it,such as Wiseco,MTC,etc

[neilbarrett]

cosworth did a 1170cc kit,best way to tell is remove the plug on no 1 or 4 and bring the piston to tdc and shine a torch down the plug hole and check the piston crown against a standard one

[johnA]

thanks for the replies gents.

[gpjes]

If it eats starter motors could be a 1260, people often forget over the years, they just know cozzy or wizzie, what colour are the gaskets that's if they're clean, you know rocker,head,base(bottom of barrels) if they're red it's a wiseco.