Cooling system flush

[Asudef]

How do I flush the system on my bike with a running tap?

There's no drain valve on the radiator to use and the only place I can see to unplug to get the entire system is the thermostat -> rad cap hose but its too short.

Should I just fill and drain a couple times?


Also bonus question: Anyone know what happens when riding without a VRR connected?

[DonTZ125]

Bikes aren't noted for their flushing friendliness; you generally need to take hoses off.

Riding without your VRR connected leads to a flat battery, a stalled engine, and a tow home (or a long push). No damage will happen in and of itself from running without the VRR; this is occasionally done by racers to remove the alternator load.

[Asudef]

Thanks, I didn't burp correctly the first time and rode it around and freaked me out with the temp gauge jumping around. Hopefully I didn't hurt the motor much.

I filled it, rocked it, squeezed the hoses I could reach and it seems to have leveled off but as I shut it off, it spat some water out of the overflow tube but the overflow tank was empty as far as I could tell. That's normal I hope...

[DonTZ125]

That's not an overflow tank, but rather an expansion tank. It has high and low marks, and running with it dry can result in air being sucked back into the cooling system.

[Asudef]

Good to know. I did fill it but it empties as it burps but I'll keep an eye on it.