My First Carb Synchronisation--Using the CarbMate!

[drdehave]

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Recently, I was shocked to estimate that I had spent at least $3,000 for leak-down compression tests and carburetor synchronisations (Rotax 912 ULS engine) on my Sting LSA over 1,400 hours of flight. So a few months ago, I bought a set of leak-down-test gages from LEAF for $78, and started monitoring my own compression. Last week I forked $95 to Amazon for the TS-111 CarbMate carburetor synchronizer (And, instead of the $80 Rotax vacuum-hose adapter, I made my own from about $15 in parts from the hardware store.) and performed my first carburetor synchronisation on my engine. The result was so “sweet” and fulfilling, I decided to spill the story here.

The CarbMate balancer doesn’t have dial gages, only LEDs, and when you light up the “happy face” in the middle, you’re there! I was able to do it alone, by running the engine to see where it was, then shutting down and making adjustments (to throttle-cable adjusters), then running again (trial and error), until solidly on the happy face. Also, the dial on the left (see photo) allows you to progressively increase the resolution. However, I couldn’t get to the finest (0.5 cm of mercury) resolution-–only to the 1.0 cm resolution, where just 1/6 to 1/8- turn of the adjusting nut was making very significant changes to balance. This (such small movement of the nut) blew my mind!

Then, I went out and flew my airplane for 10 hours over three days for evaluation. I suppose it may only be the “placebo effect,” but I am absolutely convinced it has never run so smoothly–-and thus been balanced so well! And the “throttle-back harmonics” my airplane is prone to at higher (>5,000') elevations using the DUC Swirl propeller, have greatly diminished.

I know there are some things that can be done with pneumatic dial gages that happy-face LEDs can’t. But for just balancing the two Rotax carbs to perfection, this CarbMate is awesome. I’m kicking myself for waiting so long to fork for one–-and to start doing my own balancing!

Rich

[Wm.Ince]

Thanks Rich for the report and your experience.
You are the second guy, I know, who has given the product a positive endorsement. I'm now sold.
I plan on getting one soon, from Lockwood.

Can you give us an idea on what you procured (and where), in place of, the $80 Rotax vacuum-hose adapter?

Thank you in advance.

[drdehave]

Darn, Bill, I knew somebody was going to ask--and I sadly don't have the specifics! However, what I did was to take the 3' vacuum lines that come with it and a little piece of the hose that connects the "crossover tube" to carb, to the hardware store. What you have to do is step that little hose UP to the much bigger Rotax, I think 12mm, inside diameter hose (and OVER the 12mm tube). You can do this with various brass or plastic "barb" fittings. I also used short pieces of air hose (the red hose you see) for my adaption. There was also one more little "trick." One plastic step-up barb end was too big to fit inside the Rotax cross-over hose, so I placed it into a battery-powered drill chuck and ground it down to size using sandpaper. Just be sure you keep the lengths of the modified 3' stock lines, the same. Otherwise, the CarbMate does not work properly.

One more caveat. The stock 3' lines are usable, but a tad short, for ease of use. That, and fooling around at the hardware store for an hour, would for some, make the case to just fork the $80 for the 6-ft-long Rotax adapters. Me, I had the time to play at the hardware store...it takes some creativity though.

(PS: Apparently, Rotax likes the CarbMate, too! Check out this video: https://www.youtube.com/watch?v=5wXfiVBO2Uc)

[Wm.Ince]

Thanks again Rich.

[drseti]

I've been using the carb mate for about 3 years now, with good results. I did spring for the Rotax adapter kit from Lockwood. And, in the interest of safety, I do what Rich does, adjusting cable tensions with the engin off, little by little, instead of working close to a spinning prop.

[drdehave]

"I've been using the carb mate for about 3 years now, with good results."

Paul:

Just curious. Are you ever able to achieve the highest resolution? I found that once I got there, even tiny changes to an adjusting nut would send it back in the other direction, and I just finally gave up on it (i.e., at the 0.5 level). What I achieved at about the 1.0 level was darned good, though!

Rich

[drseti]

Same here, Rich.