Big bore ID help?

Hello guys,
Ive got some newbie questions about the claimed big bore kit my bike has that the PO said was done.
The story is that it has the 900 crank but the top end from a 1000. The jug stamp is 903cc. I understand it could be bored out to accept the 1000cc pistons. My question is can I visually check this with the cylinder head off? Do the pistons look visually different? What would the stock bore size be as I can then measure to find the overbore.
Also the same for the cams. Are there difference between the 900/1000? Stamp codes etc. I could measure the lobes maybe?
I just want to know what truly is in my motor when I go to disassemble it, and then I can mod from there with aftermarket parts.

Thanks for all your help.

hal0tw0 wrote:

Hello guys,
Ive got some newbie questions about the claimed big bore kit my bike has that the PO said was done.
The story is that it has the 900 crank but the top end from a 1000. The jug stamp is 903cc. I understand it could be bored out to accept the 1000cc pistons. My question is can I visually check this with the cylinder head off? Do the pistons look visually different? What would the stock bore size be as I can then measure to find the overbore.
Also the same for the cams. Are there difference between the 900/1000? Stamp codes etc. I could measure the lobes maybe?
I just want to know what truly is in my motor when I go to disassemble it, and then I can mod from there with aftermarket parts.

Thanks for all your help.

Stock cams are the same. 900 motor has 66mm bore where 1000 motor has 70mm bore.

If it has a big bore kit they might or might not be OEM pistons. Post pictures of the cams and the pistons when you get it apart.

thanks for the info. I may tackle this over the winter when I swap to the GSXR forks and the bike is down.