912 UL jetting

For the 912 UL carbs, what should the air/fuel ratio screw be set to.............? 1 turn out, 1.5 turns out........ etc.......? 

Thanks

Hello Jesse

The factory setting is always 1.5 turns.  If you have to deviate that suggests something else is wrong. 

Cheers

Thanks for the reply. I will check my carbs as soon as I get a chance. 

Rotax Wizard wrote:

Hello Jesse

The factory setting is always 1.5 turns.  If you have to deviate that suggests something else is wrong. 

Cheers

my teeth always grind a bit when I see this information repeated without further explanation. 

In my experinece thus far with my AFR system installed on at least 5x 912's in my region alone the 1.5 turns out from fully seated results in engines running in the 14.9 to 15.2 to 1 ration from an AFR standpoint - and this was measured with a computer system, not assumptions or by watching EGT's. In two instances, the carbs were fresh overhaul delivered back to the aircraft owner directly from Leading Edge and the carbs read 15:1 at idle. 

The callouts within the manual are a STARTING POINT. you have to consider that while engine components are being produced, the tooling wears and the material proeprties are not identical between batches of raw material. With these slight variations in the tooling as well as the base material, variation is EXTREMELY likely.

Anyone who has spent any time tuning engines in cars, motorcycles, boats, even a single cylinder go-kart knows that while you are provided some numbers in terms of a starting point when your going through the manuals, tuning is ALWAYS required. If you want to know how your engine is behaving while running throughout the entier RPM range, I strongly suggest borrowing, renting, or buying an AFR meter and tuning the engine right. Ive mentioned it here as well as a few other sites - when I started tuning the engine, I ended up gaining 900 RPM as a result of the attention placed into just the carb jetting. Its worth doing right. If youd like to see the process and the video proof of these gains, they are posted on Youtube.

hi "Aviation Design"

I am not going to run a full tutorial on how to best set your Bing.  To be clear I raced extensively during my life and am well aware of all the variants that can occur.  Bash my comment if you like but I find your input a bit argumentative.  Jetting is sensitive to a lot of things, like the fuel we use and the load you put on it with pitch.  I have never in over 35 years with the 9 series burned one down with factory jetting. Just my view on factory jetting. 

Cheers