I am not a motorcycle repair garage but own a few bikes which I service and repair myself.
Can anyone please advice which diagnostic equipment or software is most suitable
for use on Japanese bikes mostly Yamaha and Kawasaki. It needs to be able to work on Yamaha's ABS and if possible immobilizer systems. Thanks
The most useful tools (and I realize this is not what you mean) I have, for working on a bike, are my two hands and my eyes and ears. That's just to say that, when possible, when I hear or feel a problem, I can usually fix it with more common tools. Analytical equipment is fine, and has its place, of course.
There's a guy that I used exclusively when I needed work done on the Jap bikes I owned. I can't tell you that I EVER saw much in the way of fancy evaluation equipment around his shop. He just had an "ear" (if you will) for problems, and was able to work em out with very typical tooling.
I agree - the best guide is a combination of common sense, a voltmeter, and a good shop manual. Most Suzuki models have a connector, when you bridge two pins, the EFI will display an error code to help diagnose problems. I'm sure that other manufacturers have something similar, but you need to have a shop manual (or try Googling it) to know which connector and which pins need to be bridged. Otherwise, most of the time, it's good, old-fashioned detective work - following the wires, looking for where a signal gets lost.