Hey Phil,
Can't sleep so I was rereading your post. I put your rpm's into the pulley/rpm calculater along with my measurements. At 2300 engine rpm puts the flywheel speed at approx 415 rpm. At 2500 engine rpm, it puts flywheels at 450 rpm. Earlier BSD stated that he thought the clutch engaged at 2300 rpm. Even if someone were to spin it up faster than that and then slow to 2300rpm, it will never support any kind of load at the engagement rpm. I'm comparing that to a snowmobile, you can spin the rpm up to get it moving, and then lower it to run at the engagement rpm. It will go, but it will stop on the slightest incline unless you give it some gas. Not to mention, at 2300 rpm, the motor has limited torque and hp. Now at 2500rpm, you've eliminated any engagement/load issues, but it will still limit the hp/torque somewhat (which imho hp is not as necessary in kinetics). BUT, the bigger issue, at 2500rpm the flywheels are then spinning over 450rpm, which imho is still 100-150 rpm too fast. The DR advertises approx 400rpm, and SS says 300rpm max. I would have to guess 2500 rpm is pretty close to where I've been running mine all the time. Your findings, with your tach, have really confirmed what I've been saying all along, these things are way too fast. I still think the engagement "cam" needs reworked so there isn't any way of disengaging, except for manually or at the end of the stroke. But they need to slow the flywheels down if they want to keep them together for the long haul. If they don't slow them down, then I'll at least slow mine down.
Later Phil, let us know what you find out.