Precision tuning the Rotax 912 UL/ULS

[trond]

I am at exactly 12.8 at WOT so that is good. This is important as you say to get power

Cruise now at 15 and it runs fine there too. Lean stuttering now gone at cruise which was priority. Much better than it was. I only cut off two coils from the springs but it was an improvement. Supports the vacuum theory. Might try cutting off one more coil later or not, for now I am happy and plane is operative.

runs fine and most efficiently are two very different things. The engine shouldn’t bog when seeing the numbers you’re providing, but you’re also not pulling peak power at any rpm in which your ratio is outside of 12.8 to 13.1 ( I believe the scientifically proven upper threshold is actually more around 14 but I aim for that 13.1 for consistency).

those FI systems are very nice, but I’m with you - I cannot justify that level of expense for my little 80hp sky dirt bike. Maybe if there was a way to make some of that money back, but since I’m no competitive racer or silver spoon child, I’ll stick with the carbs for now haha