hi everyone, would just like to know how hot does a ruby have to be before the cooling fan comes on.

 

The thermostat starts to open at between 176 and 183 degrees F. It is fully open at 203'F. The radiator cap should hold 20 PSI. I can't find a specification, but the thermostat and radiator cap would indicate the cooling fan comes on close to 220 degrees F. Maybe a few degrees sooner.

 

yep, sounds right. whats funny is my fan comes on more in cold snow rideing than hot summer.... i guess the slow snow pushing really gets er warm.

I wonder how hot my air cooled XR250R gets, there has been times where the clutch cover burns my socks in hot summer days on tight trails.
I stuck a meat therometer in my old XR500R's oil back in the day and watched it climb past 300F