How Long Should The Fan Take To Kick In

covid-21 · Sep 28, 2020

I'm gonna change the coolant today and I was perusing stuart fillingham's video on this. After filling it he suggests running it till 'the fans kick in', and if they come on a bit quick, maybe there's an air lock. I'm wondering on a 20ºC day, how long should it be approximately till the bike gets hot enough for the fans to begin.

Also Stuart says to run it for maybe another two cycles of the cooling fan. Does this mean just leave it running continuously till the fan starts stops and starts again? Is this OK to do? It seems a little strange, but then I've never had a water cooled bike before.

Ducatitotriumph · Sep 29, 2020

Should take about 8 mins ish.
Unfortunately, i'm not sure what bike you have but my speed triple takes about that.
The cycle would be to get it to fans on, let it run for 1 more min and then let it cool down again.
Then repeat 2 more times.
In between the cooling phases (when cold) check the level and top up if reqd. Might have to repeat that.

covid-21 · Sep 30, 2020

OK this is a Street Twin. I took the bike for a run when I finished yesterday, and it only needed another maybe <100ml. Normally when I have put a temp gun on the radiator after a long ride it's usually about 87C and the front of the cylinders are 107C.

I let the bike warm up and after 28 minutes the cylinder on the exhaust side was up to 108C and the radiator was up to 92C but the fan still did not start. I didn't want to keep on with this.

I'll check the radiator level one more time after it cools down but I think I'm good to go. It's not hot today but it's not cold either about 20C ambient.