This was a project that Chris and I began discussing a few years ago, and it is something that I stand behind 100%. This video really explains everything there is to know about the jet kits and their benefits. Pro Flow Jets for the Rotax Max engines is the only way to accurately test jet sizes and not using pin gauges that most teams and engine builders currently use.
I have been driving Rotax since 2003, and up until now, I never knew what jet I was actually putting in my carburetor. Now look at the whole picture. If there are 50,000 Rotax engines being used, that means 50,000 people don’t really know if that 128 thats in their engine could be a 122, 0r a 130 main jet.
Dellorto mass produces the jets. They would be machined within a certain technical spec, which in industry standard is accurate. However that deviation is what causes problems when trying to maximize performance of the engine where jetting is so critical. Starting 2016 with the EVO engine. Jetting has become even more critical. The reason being is we are using even smaller jets. The smaller the jets the more precise. Take a look at this example.
Non Evo 2015 Junior/Senior
Running a 160 main. Switching to a 162. 2 points different. = 1.25% difference.
Evo 2016 Junior/Senior
Running a 120 main. Switching to a 122. 2 points different. = 1.66% difference.
Running a 108 main. Switching to a 110. 3 points different. = 1.85% difference.
The jets we run now are almost 75% smaller in size. With that the percentage in size is increased. So before with none evo jetting was less critical.