I wanted to make sure the air/fuel ratio was good with my Akropovic slip-on muffler, so I decided to put the bike on a dyno. The power output numbers were only a bonus.
I have to say that I'm extremely impressed and pleased with Zongshen and the CSC RX3. As you can see in the plot below, my power output was very consistent, and the air fuel ratio was just about spot-on where it needed to be. It only runs slightly lean at wide open throttle between 8,000 and 9,000 rpm.
I didn't test with the stock exhaust (I probably should have to baseline.) But I have to believe the stock exhaust is not a lot more restrictive than the Akrapovic, so if you do change cans, do it for tone and weight, but not so much for power.
The guy running the dyno was impressed by the RX3. The shop services all bikes... European, Japanese, Chinese...and scooters too. He said that in his experience, Chinese bikes will come in with poorly tapped and aligned bolt holes, substandard quality, and a lot of imitation of other bikes' engines or parts. But he liked what he saw on the RX3. And he was also surprised that there wasn't a hard fuel cut-off like many Japanese bikes. The RX3 liked to rev past redline and up to 10,500 as you can see on the dyno graph.
Despite my enthusiasm about the horsepower number, I have to provide a caveat that every dyno is different, and every day's weather conditions are different. The main advantage of a dyno is to do a baseline (before) run, and a run again after changing a part. But taking just my numbers, and applying the standard 10% correction, it compares very favorably to the factory's numbers (as measured from the crank.) I'm impressed.
OK - enough babble. Here's the bike (first RX3 in the US on a dyno?), the corrected power and the dyno plot.