Coolant Burping

I was burping the coolant after changing the fluid and am not sure I am doing this right. After filling the coolant I turned the bike on, radiator cap off and let it warm up. Coolant slowly began to rise and lightly trickle out from the radiator fill hole as the bike warmed up. Should I let the coolant warm up and then blip the throttle or just begin to do it immediately while still cool and not let the coolant get warm enough to rise and trickle? Seems to me that to fully get air out the thermostat should be open. Is this correct?

The thermostat has to open to purge all the air. So yes, let it come up. I don't fill it to the top when cold to allow for some expansion. For it to work the rad cap must be the highest point in the system, so the bike must be on the side stand. I've never worried much about the throttle - as long as it warms enough to cycle the fan a couple of times it seems to work for me.

That's what I was thinking, that the thermostat needs to open to release any trapped air. I will turkey baste a little out to lessen the spillage.

Yes, you are correct Sir. Changed mine last year this exact way. Allow to warm up. Coolant level will rise and you should notice when thermostat opens. Cap off when coolant is up to the top. Also, drain and fill reservoir with fresh coolant beforehand, as this will be drawn into the sealed system as it cools down.

Mate,

Get yourself a spill free coolant funnel ( see photo) and connect using the correct cap which comes with the kit. You can then fill the bike with coolant and run it up watching all of the air come out through the funnel. As the coolant gets warm it will rise in the funnel, air will come out as large bubbles and then as small almost fizzy bubbles as the thermostat opens and all of the air is released. You will see the level of coolant in the funnel drop slightly as the thermostat opens. I run the bike like this mainly at idle but every so often I find if you turn the bike off, air is released as the flow has stopped. Restart the bike and idle again and continue until all air has been released. It can take a while and at times you will feel that you have a leaking head gasket as towards the end you get loads of really small fizzy air coming out. It does stop eventually. You can then let the bike cool completely, with funnel still connected, that will allow all of the coolant that is still in the funnel to fill the system as the water cools.

Once totally cooled take the bike off the side stand and lean the bike right over, with the funnel at the highest point, to ensure all of the air has come out of the second radiator as the front hose that connects the two radiators is not a straight hose and air collects in there as well as the top second radiator where the thermo switch is to operate the fan. Once done, remove and fit your radiator cap. Job done.

I believe the manual says get it to operating temperature then blip the throttle (4-5k rpm) with the cap off a couple of times.

Another trick I was told was to lean it right over with the cap off once you've done the blipping. You'll need a friend, lean it right over, left side down, until the footpeg is almost scraping. This allows a small amount of trapped air out.

Tried to do the burping routine but kept getting surges of coolant spilling out as it headed towards thermostat opening temps. Caught a lot with a baster but once the thermostat opened was still getting coolant overflow with the cap off as I revved it up. Marooncobra's suggestion seems like the best route. For only $25.00 it makes for a pretty spill proof adventure and saves unnecessary wasted coolant. It is something I will use again many times over so not a one time niche tool.

expvet

Tried to do the burping routine but kept getting surges of coolant spilling out as it headed towards thermostat opening temps. Caught a lot with a baster but once the thermostat opened was still getting coolant overflow with the cap off as I revved it up. Marooncobra's suggestion seems like the best route. For only $25.00 it makes for a pretty spill proof adventure and saves unnecessary wasted coolant. It is something I will use again many times over so not a one time niche tool.

Glad to hear the spill proof funnel worked out for you. I have had one for years and once you have used it, and see how easy it is to fill and remove air with little to no loss or coolant, you will never use anything else for both bikes and cars. I am surprised it isn't well publicised as the standard way of removing air from our VFR cooling systems.