KDX engine operating temperature

[skipro3]

I was out for a ride with another KDXer and I "borrowed"an infrared thermal temperature gauge from work that is used to check remote bearing temeratures. It has a laser beam that when pointed at an object will display the temperature of whatever the beam is touching. In this case, my engine measured consistantly 25 to 30 degrees warmer than my buddies. He has a KDX200 with porting and head mods, K30 pipe, airbox lid removed, and I have a 220 stock except for weisco piston, K35 pipe, boyesen reeds, airbox lid removed. We both run race gas and same oil/fuel ratio. My temp. is 180 and his 150. He thinks it is due to the fact he removed his overflow tank thereby increasing air flow over the radiator. I'm using Evans antifreeze and he is using Prestone 50/50. Anyone else have a theroy as to why one is warmer than the other and what the temp. range should be? Both of us have the bikes jetted near perfect based on plug readings. :flame: :flame: :flame:

 

[mnnthbx]

180 & 150 sounds fine to me (though I have little knowledge of correct temp). On my new stock 200, I can only hold my hand to the motor for one second or so. This is running in air temps of 75.

 

[Robcolo]

Nobody--including Kawasaki or Fredette -- seems to have a good explanation of why many 220s run [very] hot and the 200s don't. If you weren't running the Evans NGP it would be running even hotter -- and boiling. Moving the overflow bottle definately increases airflow but that still didn't stop mine from boiling--only the Evans NGP did. One possibility is the stinger on the expansion chamber. If the pipe was designed for a 200cc displacement -and maybe on the tight side - it might just create a little too much back pressure with the larger engine. ??