I am working on a rough running 916. The symptoms are under slight throttle at less the 4000 RPMs and at idle it will make a "pssst" coming from right under the tank followed by a misfire and RPM drop. The bike was being parted out so I had to get a new computer and FIM chip so I am thinking its a fuel injection adjustment issue.
I have read a lot about the TPS adjustment, TB sync, Air By-Pass adjustment to 1100 RPMs, and CO adjustment. I was wondering what Throttle Body sync tool, manometer, are people using? I have heard of the Twin Max, Carb Tune, old school mercury gauge. or the homemade from tubing and ATF or Stabil fluid.
I gave the homemade method a try with a Triumph I have and didn't have much sucess because the fluid I was using, Stabil, would just slosh around even with 11ft of tubing.
Also I believe the port for testing port is on the right hand side of the bike behind a plug, so I am guessing you need to screw in an adapter to hook the tube up to. Is that something readily available at a hardware store or is that a custom order item?
The Meter Rule and Clear Tubing (2-Stroke oil) method works really well. I have dial gauges but they are not nearly as good. The needle flutters around too much and they are not as accurate. I believe the best, though are the proper old mercury manometers.
I use the brass adapters that came with my dial gauges with the Clear Tube and 2-Stroke oil.
Check to make sure that the bushes in the ends of the butterflys are not worn which makes the butterflys sloppy.
An easy way to (might seem rough but works very well) set the butterflys is to open the throttle to 40-60% and hold/jam it there.
If you have access to a good set of Fractional drills you can then proceed to match the openings by slipping a fractional drill down the throttle/butterfly gap. The fractional drills go up in .1 increments so you can get a very accurate match.
The 40-60% opening corresponds to the most used area of the throttle.