912ULS Rough Sync At Low Revs

Yeah I watched the video on this site to do the sync. I also read a post by Roger Lee (Carb sync for beginners) on how to do it. I cross checked these methods with a rotax mechanic I have limited access to. The only thing I modified was I used 3500 rpm instead of 2500 rpm.

I'm going to try again at 2500 rpm and use a different sync tool in case the carbmate is busted.

Thanks for the help / advice.

Make sure the carburetor pistons move up and down freely, if not clean and lube the slider bearing under the carburetor chamber cap. If they do not move freely you can get intermittent out of sync conditions when changing throttle positions. Also as a final test after a pneumatic sync and after the sync equipment has been removed pinch a hose on the compensation tube you should not be able to detect change in vibration or a change in engine sound if the sync is perfect/correct. My carb mate went out of calibration after the warranty expired so I use one vacuum gauge with a Y connection and dampening valves. No two gauges are the same so its easier to know your synced when the gauge stops moving as I switch the valves from side to side.