WORD. Leaving open-ended threads is really the issue isn't it? No need to answer, closed thread, it's a dud.

I replaced the rear rotor with the EBC rotor (md661, beemer boneyard) with ebc pads and more I get an intermittent ABS Light flash while riding. If I tap the rear brake, it stops for a while. Everything is snug, the abs ring doesn't move on the rotor.

in the meantime can anyone post the process to check the air flow meter…
 Lastly, there is a fuel vacuum switch near the fuel regulator. It was eliminated in later models. What does it do? Should I leave it be?

The air flow meter is dealt with in Bert's guide, which I think you have.

It's not a fuel vacuum switch, it's a vacuum switch. Check anyway the vacuum hose to the fuel pressure regulator, that it's not leaking, or kinked, or blocked, or partially blocked. Do these checks also for the hose to the vacuum switch.

Some people remove it because they notice no improvement in performance with it connected. With that reasoning you could remove a wheel nut and throw it in the bin, there would be no drop in performance but after a few years the disc might develop a warp. It might not warp either, but why bother second guessing the engineer's who designed it that way? It's not meant to improve performance, it's there to improve fuel economy, reduce pollution etc, mainly while cruising. They have put it there for a reason, so I think leave it connected.

At higher vacuum you want to advance the ignition timing because it takes longer for the detonation to complete in these situations. You can use an LED test light to check that it sends a signal to the ignition control unit, from memory I think it only sends a signal at part throttle. You could use a timing gun to check that the computer is altering the timing. I guess no one has done that yet on this forum. There might even be a drop in revs if it is plugged to remove the signal while cruising.

this happened suddenly. The bike was running flawlessly....Could BOTH coils get tired at the same time?

One possibility is that one coil was working well and the other coil was working, but not well. A crack could show an open circuit when tested with a multimeter, but the high current could jump the gap while running, which would be about zilch millimetres. It jumps a big gap at the spark plugs (one wasted) Now if the other coil fails, the problem becomes much worse.

I don't think the spark plug leads have been tested yet, that would be worth a look. Original leads from a K75 should not be used, they're different.

Thanks, Scott… Laitch, I’ll get the orange cap ones on eBay. This will take a week or so …
in the meantime can anyone post the process to check the air flow meter…
 Lastly, there is a fuel vacuum switch near the fuel regulator. It was eliminated in later models. What does it do? Should I leave it be?