JAGUAR WONT START

A 4 cycle Honda cycle? I don't think the amperage will be enough from a bike. You probably need to let the battery come up a bit, so jump it with another auto and first leave the donor car running for a while. Make sure the connections are good.

The size of the engine makes no difference -- it is the size of the alternator and the electrical power than is the concern. Usually a smaller car has smaller amperage needs. Try it again with the Honda but rev the engine in order to take the RPMs of the engine up. This should produce enough electrical power to start the Jag.

Make sure to put red to positive and black to negative off the Honda battery and Black to metal on the Jaguar so you don't fry anything on the Jag.

How long did your XK8 sit? My XJ40 sits for a month at a time and starts right up. You may have other problems with your XK8.

Webserve.

Is the battery completely flat ? If so you are probably better off disconnecting and recharging the battery prior to re-starting and resetting codes. You are advised against jump starting modern cars due to potential damage that can occur with the ECU.

The battery is completely flat.. But even if I jump it shouldnt it start?