Bongo Fury

Having replaced pretty much the entire ignition system, I thought I'd have a crack at checking the timing. According to the manual:

1) short GND pin to TEN on diagnostic socket with jumper wire
2) revs between 500 & 900 RPM
3) yellow mark on pulley should be BTDC 12 +- 1 degree
4) remove jumper wire
5) check mark on pulley within ATDC 6 and BTDC 23 degrees

Questions:

What does connecting the pins together do?
The range after removing the jumper is 30 degrees which is pretty huge and well off the timing mark gauge. That doesn't sound anywhere near correct.

I don't know what the techie term is and i may be wrong so i will sit on the fence as usual-so the only light i can shed on it simon is that ecu won't accept the change, unless you ground pin ten it will revert back to prior setting basically cutting the ecu out of the equation, i found it very difficult to pick up with the gun untill i tipexed the pulley, if i remember right there is a small pin hole aswell as the faint worn yellow line that was on mine (again i will sit on the fence), while your there read the ecu with an old school multimeter for any fault codes.

Dar