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Aux cooling fans on rm125

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Debating puting small electric fans on my rm125 to aid in keeping her a little cooler in the trails when I'm riding some tighter paths, has anyone ever done this?

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You missed the point.  The bike does not have enough extra power to power ANYTHING.  If you can run the fan on a temperature switch so that it only comes on for 10 minutes or so on a 2 hour trail ride a total loss battery system would be your best bet.  A charging system that siphons off the minimum excess that the bikes electricals can provide may be able to keep up for almost all conditions.  Really, though, a 125cc 2-stroke makes so little heat with such big radiators.  Even the pros running nasty events like Erzberg have minimal overheating problems.

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I'm just spitballing ideas here. I have yet to look into what kind of current is coming out of the stator. All I was asking is if people had done it. No need to get frustrated. But in any case mine runs a little hot for the trails I've been riding. Even with proper fluid levels and viscosity. The fans would be more to cool while sitting as opposed to riding. That being said a Stand alone battery system would probably work but I was just throwing ideas out there

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Fans are corrective in any situation in which the excess heat is caused by inadequate air flow, whether standing at idle or moving slowly.

 

Unless you can get  a custom wind job done on your stator to add a "lighting coil", you can't run it off your current electrical system.

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I wonder if a case fan (from a computer) would spin off a 9v battery?

On a friends crf450 motard we needed to power his quick shifter. I used a small 1000mah 3 cell lipo (11v) from my rc airplane velcro'd in the frame out of harms way. Worked great. The same would power a pair of 120mm case fans no problem. The trick is you'd need to already have a lipo charger to make it worth while. They can be had for around $80. The batteries are like $10. I already have a charger so it was almost no cost for him. Using a 9v would be nice because you won't need a charger and it's cheap and easy.

You can get sealed bearing case fans for like 8-10$. I used them on my drz and they never failed no matter what I rode through.

Edited by D4N63R

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I wonder if a case fan (from a computer) would spin off a 9v battery?

 

 

Yes they will, and you can tape up two or three in parallel and get several hours of use out of them.  Put a switch in the circuit.

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Yes they will, and you can tape up two or three in parallel and get several hours of use out of them.  Put a switch in the circuit.

Well there you go OP. Problem solved.

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Depending on the year of the 125 will depend on your stator options. Many of the RM 125 stators can be rewound for about 45 watts of power.

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I also use a 12v computer fan on my bike and so far it has worked great but another thing to consider is putting a small expansion tank on the overflow. Burping a little coolant at times is normal but when your dirtbike pukes it onto the engine or exhaust and it starts steaming it seems like something disastrous is going on. Google turkey baster radiator tank for a cheap and functional tank plan. Good luck!

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I've all but abandoned the cooling idea just because I realized that the previous owner of the bike bent the right rad in almost 3 passages, still not the whole reason for it running hot but I really shouldn't be using a 125 that's bred for the track as a woods bike

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Good posts!

 

Last summer I rode with a guy on a CR125 in the Gifford Pinchot NF climbing some serious grades up Bishop Ridge and Hamilton Butte (do a search) and he didn't overheat, while the same ride on my XR showed 400F on the Vapor cylinder head temp.  Adding a coolant recovery tank is good idea, doesn't need much volume, the CRF250X/450Xs have one under the left side panel.

 

My CRF250X has a fan but it only comes on it if I let it idles too long, most trail riding temps are about 150F, so not needed for typical trail riding.  My Montesa 250 2T has only one radiator and I use the fan as a signal that the engine is warm enough to ride.

 

Some of the RM125s only used 1 radiator vs two for the RM250 so adding a radiator is an option to double the cooling capacity.

Edited by Chuck.

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