Precision tuning the Rotax 912 UL/ULS

[trond]

I have solved my carburettion issues by installing LAD Aero EFI. Engine is very happy and purrs at any RPM. It idles nicely at 1500 RPM. It was a easy and clean intall and I found user support to be excellent. I went with lambda control and automatic switchover to back up fuel pump. Also changed to a Shindengen RR and warning LED and it seems to work well. Have 25 hours on the install now and could not be more happy

[mike67]

Hi guys


there is now a distributor in Canada for the LAD aero injector kit

[Dusty]

I've recently been down the tuning rabbit hole with a 912 ul zipper. I hope my findings may be of some help to someone.
My starting point is a late 300 hrs ul. It ran ok at all aspects of flight. My flying is mostly 1000 to 4000 ft with occasionally 10.000 ft
Fuel is 95 octane .float levels are 12.5 mm from the fuel bowl edge.
I have always experienced high egt at wot. I installed a 1 inch balance tube in preperation for a zipper install ,the idle was vastly better .
The 104 hp high torque kit was fitted . The exhaust valves showed signs of heat stress. 915 valves were fitted to cnc machined heads.
Wot egt was still high and an exhaust gas test confirmed 15.3 so we installed 165 mains which helped a bit.(158 std)
On a hunch I believed the needles were limiting the fuel at wot.
I removed the main jets completly and did a run up. The egt went low at wot but all else stayed the same, bingo!
The needles were reprofiled in the lower 8 mm similar to the Jabari carb.
We re checked the ratios (#30 idle jets were also fitted as the idle screws had to be nearly all in for smooth idling at less than 1700 rpm
Although not technically perfect I am more than happy with egt's and smoothness at all throttle settings.
I will post the gas results when I find the safe place I put them.
These results may not work on a uls as the fuel delivery is quite different to the ul

[AvDES LLC]

Great input Dusty! If youre at all wanting to hone in on how the engine is performing from a fueling standpoint throughout the RPM range, an AEM AFR meter is a cheap means to do so. I am not at all surprised that you ended up stepping up the main jet as that was one of the issues I had at 6000 ft where I currently reside. Good addition to the conversation!

In regard to the mention of EFI - I definitely agree that EFI is a way to go if youd like to have an almost plug and play system. For a majority of people flying behind a ul or older ULS, it doesnt make sense from a cost standpoint to put a few grand into a fuel delivery system. that my .02 and im POSITIVE there will be those that do not agree with that sentiment.