Solo Carb Balancing

[DHeal]

Not wanting to subject myself or any of my friends to standing near a rapidly turning propeller while looking at two carb balancing gauges and wanting to do both the engine operating monitoring and looking at the carb balancing gauges at the same time myself, I devised the following plan:

I positioned the carb balancing gauges inside of the cockpit by adding extensions to the two rubber hoses -- the extensions' were cut so that there is equal length between each gauge and the respective connection elbow on the intake manifold (not that having the lengths the same makes any difference at all). I ran the two extended rubber hoses through the open air vent on the copilot side and positioned the gauges on the copilot seat where they fall readily to hand as the British say.

Next, I tied a length of 50# monofilament fishing line to the top of each throttle arm and ran each line aft under the canopy fairing and into the cockpit where I terminated each line with a little "finger pull" loop.

Now I can start up the engine in the safety of the closed (and warm!) cockpit and gently pull on each loop to see what carb needs to be tweaked to balance the gauges. Then I shut down the engine, make the adjustment on the carb linkage, restart the engine and double-check my settings. Repeat, as necessary to achieve vacuum perfection.

This procedure worked great for me. Does anyone out there in ROTAX-land see any flaw in this method? -- YMMV.

 

[Bill_H]

I balance mine alone as well. Neat idea with the monofilament. I found that with the canopy sitting on its handle the lines would come into the cockpit under the front of it. I marked the lines and gauges and can tell which one needs adjustment and in what direction.

I don't have it handy but I remember reading somewhere that so many flat's on the nuts holding the throttle cable adjustment equated to a certain amount of MP (Van's initial commissioning procedures maybe? On a trip without my references...) and that works for me - so far has taken only a couple of minor adjustments.

 

[RFSchaller]

I use the electronic meter. I think it's called carb mate. Every time I use it I draw a slight vacuum on one side and remind myself which way the lights will go.

 

[Dave12]

Good idea. Watch it with the canopy resting on the handle though, I did that once and it was ok at idle and slightly above, but I advanced the throttle , the cabin filled with air (pressure) and actually forced the canopy up with a vengeance. Luckily I caught it before any damage.

 

[roger lee]

I must do at least 75 carb syncs a year. I usually just put my wife behind the controls. (but not if she is mad at me0.
Working behind the prop is quite easy and relativly safe if done correctly. A normal carb sync takes me about 15 min. A carb balance from **** can take up to 1 hour. The problem with these hard to do balances is almost always a poor throttler setup. The cables have too many bends, the internal wire too thick, corrosion in the wire sheath, a poorly designed throttle system or just a cheap throttle. Lately I have pulled a couple of throttles out of planes and put in better throttle systems and their carb sync issues disappeared. If your carbs will not return to the same place every time you move the throttle then you have one of those systems. If you design your system use as few cable bends as possible, but the biggest key is to use smaller cable size. This allows the cables to move more freely through the sheath and allows the carb springs to return the carb to exactly the same place every time. You do not necessarily need a stiff push type cable system. You will manual pull a thinner cable closed and the carb springs will pull the cables to the open position. Flight Design uses 1.2mm cable in their system and it slides like glass and the carbs always move in perfect unison every time.

Don't be afraid to spend a few extra dollars on a good system.