got an '06 bruin. last 2 times i have ridden a long time, @ 4 hours or so, my oil temp light came on. the oil level is OK, the cooling fan does come on. Light comes on right after riding at or close to full throttle for 10 minutes or so. What could be my problem?

 

you need to check the if the fan runs atall. if you can hotwire the fan, and it works, then you have a temp sensor that is not working.

 

dirty radiators can do that, or if you got old crummy oil that can also cause an overheating issue.

 

the bruin is 350cc, oil cooled if im not mistaken. but the fan should kick on even if the oil is gunky. true 91warrior357, if the oil cooler is dirty that would impeed cooling as well

 

How is your jetting?, proper jetting insures cooler cylinder temps also helping regulate overall engine temp.

 

from what iv seen if your too lean, and running too hot, your exhaust pipe will heat up and be glowing red hot. but if its only overheating at high rmp's its more likely an oil prob, if your header isnt glowing!

 

Also is there any mud or dirt packed in your oil cooler or on or around your motor, I have seen where oil coolers and radiators get mud packed in them and that will kill an engine, it will cause them to hold a ton of heat.