TOPIC:

Can anyone confirm if this piston is a Wiseco 810/69mm piston for a gpz750 Thanks in advance

Yes!
According to the Wiseco website it is.

Thanks Zed, I wasn't sure if they were turbo pistons but the website confirms different part no. I'm struggling to find why I have low compression after a rebuild. That rules out the piston.

Cam timing?
Steve

Thanks Steve, I've checked TDC with a TDC bolt and found the T mark out about 1mm. I,m running ZX cams with adjustable cam sprockets and have set them to 105.
I rebuilt the engine after blowing the head gasket at Eastern Creek Racetrack on a ride/flog day. It had done 20,000 km since the oringinal build and ran about 170 psi, and 91 hp at the back wheel. On the first start up it ran nicely but soon got hot. The plugs showed running lean which was odd as there had been no mag or changers to the engine. It had 120 psi across all pots and I assumed there wasn't enough compression to suck enough fuel.