I have recently brought a gsxr400 gk76a that has a headgasket problem..swapped the engine for a running one
And now I have no spark..bike has been sitting for a couple of years ... think I have got the problem down to cdi unit, pickup in the left casing, or maybe coil packs...just wondering if anyone has any usefull advice on where to get any of these parts new or any other suggestions??

Many thanks.

have you tested any of the bits you suspect?
also check the kill switch and side stand switch circuits

Well I have a multimeter but would not know where to start with it...do you have any advice on testing the cdi?

Thanks.

it would take me longer to explain how to test a cdi than to test one for you. I takes about an hour to test unless you have someone local to you you can test it on there bike. I just bench test them its a lot of pin to pin with different values