Any air trapped in the coolant system after a fluid change should be automatically vented to the atmosphere fairly quickly. Looking at the coolant system diagrams it's apparent there's only one place an air bubble could be briefly trapped -- the thermostat assembly above the engine. Any air in that location should be quickly vented out to the radiator via the thermostat assembly breather hose. Once it gets to the radiator it will eventually be pushed out to the coolant expansion tank and then to the atmosphere.
One thing could cause a problem in this scenario. If the thermostat was changed and installed incorrectly the breather hose might not evacuate all the air. The thermostat has a small breather hole which should be oriented at the top position when it's installed. If it's installed with the breather hole down lower some air might remain in the thermostat assembly. One would expect though that over a period of time any residual air would be eventually entrained in the liquid as it flowed to the radiator and make its way out to the atmosphere.
One thing in your scenario is still quite puzzling. Why did the idle rpm drop down to normal after riding for 10 kms?
One thing could cause a problem in this scenario. If the thermostat was changed and installed incorrectly the breather hose might not evacuate all the air. The thermostat has a small breather hole which should be oriented at the top position when it's installed. If it's installed with the breather hole down lower some air might remain in the thermostat assembly. One would expect though that over a period of time any residual air would be eventually entrained in the liquid as it flowed to the radiator and make its way out to the atmosphere.
One thing in your scenario is still quite puzzling. Why did the idle rpm drop down to normal after riding for 10 kms?
