Static RPM

I know. I'm late to the game responding to 7-year old posts. But, I have a new plane, with an engine/prop I don't yet understand, so I'm reading all the old posts. 

I have the same exact experience on my 912ULS and Warp 3-blade (72") as Andre. I get 5200RPM static but only 5600WOT (at low altitude), a very narrow range. I just did a prop balance (almost in balance already). The most interesting comment he made was that he was seeing almost 2400 prop rpm (while I was seeing 5200 on the Rotax tach). At 2.43 reduction, that seems to imply that my tach is reading 600 rpm low! (2400 * 2.43 = 5832). Is my math correct? I had just adjusted the prop for more RPM, thinking I was low, but now I am nervously unsure.

I run at 5000, rather than 5100-5300, because 5000 is much smoother. I'm trying to read all the old vibration posts to figure out where to diagnose that. All RPM ranges up to 5100 are smooth. WOT 5600 is OK, but not great. I'm not experienced enough to know if it is out of the ordinary vibration, I just don't like the nature of it. It's not "smooth" vibration, it's "sporadic" vibration, if that makes any sense.

I have the Rotax initial service training scheduled at Lockwood. Hope to learn a lot.

Robert

Is this a new aircraft and engine? How many hours are on the engine?

It could be something within your gearbox that is causing this vibration at high RPM. 

Because its intermittent, could also be the wheels rotating, at slightly different angle of attack.