Zongshen RX3 (overheating) venting the cooling system

[Lukas]

Recently, it got hot outside, and unfortunately, the temperature gauge started showing four bars, which hadn't happened before. So, I decided to tackle this issue. I studied the cooling system and found out that there is no option for the left radiator to self-bleed. It's an impractical design, and only the right radiator can be bled. Therefore, I removed the left cover and loosened the clamp of the upper hose. It turned out that there was a lot of air trapped, so I released it by inserting a plastic spoon between the radiator hose and the coupling. Once the air was released, I started the motorcycle to let it heat up. When it warmed up and the fans turned on, I repeated the procedure three times. This was necessary because when the system heats up, the air expands, and it might not all escape during the first bleeding. After bleeding, I hopped on the motorcycle and went for a ride, including some challenging terrain. I also encountered some traffic jams. After waiting in traffic, the temperature gauge showed four bars, but after moving and riding for a while, it went back to three bars. I believe that was the reason why the old coolant was boiling over, rather than a faulty thermostat. When the air expanded, it exited through the expansion tank, causing bubbling. Now everything is fine. I'm attaching some photos. I hope this helps someone because I couldn't find a method anywhere to bleed this system, so I came up with my own. Therefore, when the coolant is boiling and the temperature gauge is acting up, first thoroughly bleed the system before considering replacing the thermostat or other components.