Thanks for the replies. I was wondering if there was a permanently-mounted unit available for RTVs, but I’ll try the B&S unit. My most important reason is to adjust the idle speed to the recommendation made in the manuals, but they don’t tell how to determine that RPM.
I believe the previous owner of my barely-used X900 had tried to make it idle very slowly because the safety-wire on the idle-adjustment screw was stretched, and the engine vibrated excessively IMO. I adjusted it to idle more smoothly but I would like to confirm its at the recommended speed.