1999 Aprilia RS250 race bike is running very cold. Idle will bring temp up to 150F or so, but once the bike starts to move, it drops back down to 100F or lower. Thermostat, temp sender, and temp gauge have been replaced. Bike is running a mixture of distilled water and water wetter (no coolant). Covering 40% of the radiator has not helped either. Any ideas? Ambient temperature has been everywhere from 75F-90F, and has no effect on the issue.
Hi mate when you put the coolant do you bleed the system to get the air out of the cylinder
YES THAT WOULD BE TRUE MATE HAVE YOU PUT THE THERMOSTATE IN CORRECTLY
this is very strange buddy are you in a cold enviroment also have you tried a temperature guage on the coolant when you let it reach temperatures because you could have a faulty temp guage or sensor even know its new
another thing i can add is have you put the pipes on the correct way on the water pump you may have them the wrong way around so its pumping the water up through the raditor instead of down the radiator
×
604 views
Usually answered in minutes!
Yes, coolant was bled properly. I assume that if there was an air pocket in the system, the reult would be overly high temps, not low, correct?
just went through entire motor again. Thermostat, all hoses, sensors, etc. installed properly and in great shape. Very confused!
I agree it is very strange. I first suspected the sensor, so I replaced with new part. Then I suspected gauge, so I replace with new gauge and another new matched sensor. (i now have duplicate water temp gauges on the bike). It still reads cold, so I confirmed the reading with a pyrometer on multiple surfaces of the radiator. The gauge is correct.
×