1bdsr,
I think one of the differences here is the speed that the DS is being ridden. Your 110lb son was probably just putting around or doing short bursts of full throttle then riding slow which will definately overheat the engine. Any radiator needs air flowing through it to to cool properly, weather its from the fan or from the forward motion of the quad. Those who say they dont need a fan probably maintain a higher speed for longer periods thus cooling by motion- no fan necessary that way. I would be cerious though, to know the engine temps of the engines without fans compared with an engine with a fan. If 20+ years as a technician hasn't taught me anything else, its taught me that an engine runs better and lasts longer when it runs cool. I'll keep my fan. [img]i/expressions/face-icon-small-wink.gif[/img]

 

Is the water pump directly driven off the engine RPM's?

If so, like you say JSsDS, when someone is just putting around in low RPM the water flow through the engine is slow resulting in less cooling. The fan won't do a thing unless the water cools the engine. The water won't do a thing unless it is in (and lots of it) the engine taking the heat out of the engine and putting it into the radiator.

Could your voltage regulator be causing a problem with your fan?

 

I have a temp gauge on mine and the temp is rarly over 160*.

 

By the way - high octane only - low octane without a doubt will make you're engine run warmer. Too many people don't care about octane ratings because they don't "feel" a difference in power from one to the other. These people do not understand the true purpose of high octane, and the longevity of motor life suffers as a result.

 

My DS needs a Fan. I race desert and if the fan is not working the bike gets hot and the red light turns on. With the fan working I never see the red light. My quad has no other issues other than it needs the fan working to keep cool!

 

Has any body look in to an over size radiator so you due not need the fan.

 

If my warning light ever does come on, I'll be sure to replace my fan, but it won't be with a stock replacement - they've already proven worthless and failed for as many people as not - I will put an industrial strength version ordered from an industrial supply catalog and retrofit it, maybe even a little larger than the original for even more air flow, and refuse as needed.

All this has made me decide on getting an inline temp gauge, to be installed on the line coming from the motor, to the radiator. Its a nice feature anyway, I'd like to have it...

One more thing - in schoolboyrowe's instructions - substitute the word bushings with brushes. There are four brushes that contact the commutator. Commonplace with these non-vented little motors is for the commutator links to bridge together from brush dust, which can then overheat the windings and ruin their insulation. Such is the case on my fan.

 

Scratch that last comment about industrial supply catologs - couldn't find anything 12 volt and water tight.
www.offroadwarehouse.com seems to have the best deal I can find...

 

The mounting of the fan is one of the problem issues that Bomb addresed in the Baja- I believe the biggest reason for premature fan failure is the lack of vibration damping on the 00' and 01' models. when I torn into my fan I found that 3 of the 4 brushes had become disconnected from their leads due to excessive vibration. Last year I talked with a tech at SPAL, (the OEM for this fan) and he was involved with Bombs engineers in choosing this particular fan for this application and told me that he was not the least bit surprised to hear of the fans failing, he claimed to have advised Bombs engineers to redesign there mouting to provide some damping from the vibration and shock. He said this particular fan was designed for some piece of medical equipment and was not really suitable for an ATV type environment. He suggested that I find a way to cushion the mounts for the fan. It is easier said than done!
Does anyone know if the upgraded fan mounts are standard on the non Baja Ds from 02' and forward?

 

Got my bike back from the shop today. The dealer called and asked me to come and ride the bike at the shop to see if i could get the warning light to come on. After one hour of drag race style of riding and just all out getting on it, the warning light never came on. The dealer suggested that maybe sand had gotten into the radiator fins and had caused it to over heat. I will go riding next sunday at the dunes again to see if it happens again. I will also try and keep the radiator as clean as possible. Maybe it will help. I will let ya'll know how it goes. Has anyone heard of the sand making the bike overheat?