Please don't take offense owners, but the subject bike gets VERY hot. Check out the survey on 4strokes.com if you don't believe it. It was a grave oversight for Honda
to omit the oil cooler.
I would advise every owner to get a temp gauge, install the xr400 oil cooler ( which are dirt cheap at $130) and run 20/50 Royal Purple
oil (or some other high quality synthetic). I do that even though I live in the cool
NW. You just never know what the bike will get into. The high heat also makes the fuel funny and that is double trouble on a high comp engine.
The bike gets the hottest on high speed runs. It is easy to hit 250F and 300 is not unheard of. At those temps, even with good clean oil, the coating on the wiring will break down.
I hit 250F on my XR400 and it is completely stock. This is with a very accurate Dakota digital
guage. Oddly, I can be stuck in traffic for 30 minutes in the summer and it never gets above 215F.
A modified XR650L has twice the heat of the 400 and less area to offload it. Suzuki
was very smart to hang that giant oil cooler off to the side of their DR650.