[ruckusman]

Looking at that setup IMO you've got the ideal conditions for a 24-1 or 36-1 toothed wheel to go in place of the stock trigger AND then you could adopt the second trigger VR sensor for a cam sensor.

You can even measure the gap between the rotor and VR sensor for the cam sensor.

If the XJ600 cams are anything like the other Yamaha cams that I have seen from the period then the cam gear is bolted to the cams in the middle.

Get fractionally longer bolts and make a dished wheel with one or two teeth for the exhaust cam that's bolted on with the cam gear that runs outside the chain and close to the cam cover- then you only need a small hole in the cam cover for the trigger.

It's more work initially to make, or have made, the trigger wheels however I think it will be simpler in the long run and improve accuracy of both ignition and injection systems.

[JHolland]

The Max9926 or A2 , Is there anything else i would have to do other than soldering on the headers and plugging it into the board? The coil signal wire would just run straight to the crank pin on the UA4C?

Connecting the MAX chip in parallel to the stock ECU is going to effect the voltage, you may have issues at low RPM/cranking. With only one tooth per rev the max chip will time time out at low revs which can give big noise problems.