I had tried to order one of the commercial electronic syncronization tools but they seemed to be out of stock everywhere. The dual vacuum gage type were available but I didn't like the idea of the separate gages and potential differences between the two readings. The electronic type is really just measuring the difference between the vacuum at the two carbs not the absolute value of each which is the goal anyway, to have equal vacuum at each carb.
I had therefore ordered a differential vacuum gage and plumbed it up with adapters I machined to connect to the Rotax cross over tube as specified in the Rotax Light Maintanance Manual (LMM).
After going thru the specified procedure the engine idles much smoother.
