Mine comes on fairly often, but most of my riding is slow work under a lot of load, so airflow through the cooling fins isn't as high as it could be. I was hauling some trees out today, and even at -15C air temp the fan came on for about 5 minutes at one point.

 

Same here Chilly. I was plowing snow this weekend, it was about 1 degree out, and the fan came on a few times. I was plowing in 2nd and 3rd gear. Fresh oil, and correct level too, it's just the way these Hondas are. The fan's there for a reason, and I am glad it works.

 

I have an '02 Rancher and it doesn't come on very often. It will more than likely come on at slower ground speeds, but higher revs, such as mudding or deep snow.

 

I was wondering about my fan also. Honda 450. Where is the sensor for the fan? Is it located to read oil temp? The reason I ask is the head pipe will start to glow red sitting still at a high idle. I thought it would be enough to make the fan come on. Should I worry about the pipe. I haven't noticed it riding. Since it's air cooled is this normal.

 

The temp sensor for the fan unit looks at only oil temperature. Ideally , if it were a liquid cooled engine, it would look at coolant temp, but the oil is really the only consistent source it has to look at heat levels. Having said that, in a liquid cooled engine, oil temperature usually runs about 10-15 degrees C hotter than coolant temp, so that should give you some idea what the actual engine temperature is.

I'd be concerned about the exhaust glowing red, it's an indication of an overly lean condition. Fuel does act as a cooling agent in an engine, and what doesn't get completely burned cools valves, piston crowns, etc. If the exhaust pipe is glowing red hot, the valves are dangerously hot as well. All that keeps them from burning under this kind of condition is the contact with the valve seat, which acts as a heat sink to absorb excess heat. If a valve is set slightly too tight, it will be prone to burn.

In today's world of cleaner-burning engines, the trend is towards leaner mixtures to help meet more stringent emissions standards. Liquid cooled engines are better able to cope with this situation, having better cooling consistency throughout the engine water jacket. Air cooled engines, while enjoying greater simplicity and IMO reliability, tend to have hot spots which are hard to control effectively. The leaner mixtures use a higher air-fuel ratio, which means less unburnt fuel to help cool the internal parts of the combustion chamber.

I'd advise you to slightly richen the mixture until the red exhaust goes away. As to whether you need to richen the idle circuit, the midrange, or main jets, that depends on where the engine is running too lean. I'm guessing your spark plug is going to be pretty light colored as well. Check to make sure it is the correct heat range plug, mine had been changed to a colder plug, and was dark as a result.

 

Thanks for the reply. I'm going tomorrow to see about a jet kit. I think the atv was set up for a different location. I'm assuming my local dealer would have the right size jets for our area. Could it be that it was set up for a different area. I bought it used of course.

 

Although you could have a problem I doubt it as you are in michington and the are is still cool or cold enough as it is here in Pennsylvania. To cool the radiator and engin enough. Wait till hot summer to worry if it still does not come on. IHTH

 

I have seen exhaust glow with over rich conditions. I changed the cam in my mustang and there was not enough vacuum to keep the power valve closed. It was dumping fuel, the headers glowed bright cherry red. I also thought it meant lean, but not always.

 

Just be patient! The fan will come on eventually. Remember that it is winter, too.