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Fan not working-2018 TRS RR 300


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After a hard 10 minute climb, I noticed my fan was not running. The entire top end was very hot...water instantly sizzled on the cap and exterior cyclinder body. The hoses to and from the rad were also very hot to the touch. After cooling off, I limbed home.

I'm not sure where to start? How can I test if fan motor is gone, or temp sensor, ECI, or whatever else. I don't have much electrical experience.

All guidance is appreciated!

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Spin fan blade with hand. It should spin free. Have seen one vertigo broking small frame tab and blocking fan movement

Bypass thermostat connecting the two wires on thermostart. If fan spin. The thermostat is the one.

Connect fan on 12v from a car battery. It should work

Look for any fault connection going back the wires from fan untill magneto.

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As above, firstly bypass the thermostatic switch, this can be done just by swapping connectors by the head stock. If fan runs constantly with engine running then the thermostatic switch has gone. If still no fan then try powering the fan directly off a 12v battery to confirm if ik or not

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Probably the thermostat, test it as mentioned above, it happened to me too but also whip off your water pump cover and inspect the water pump impeller too, the fins on mine disintegrated due to the excessive heat, i replaced mine with the CSP aluminium impeller kit bit pricy at 50quid but gives me piece of mind if my thermostat ****s itself again. Goes without saying you'll have to replace your coolant too it goes very grey after a while anyway so probably due a change, remember to crack the air bleed bolt on top of the cylinder and leave an air gap at the top of the radiator when refilling so there is a little room for expansion otherwise it may build up too much pressure and blow past the impeller shaft seals.

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23 minutes ago, anachronism said:

@thumper80: What year/model is your TRS?

2017 RR, I do think it was all caused by the thermostat failing though, couldn't be certain how long it wasn't working for so could have been a while as it never blew steam out it just trickled a bit of coolant out of the pressure relief valve next to the filler cap on the radiator

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48 minutes ago, Mountainbrad said:

What coolant is everyone using? The recommended Nils product is not available in Canada. 

I've experimented with various pre-mixed designed for cars with limited success...

What do you mean by "limited success"?

What made you think the coolant was no good?

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First up, I'm a fledging rookie mechanic. I've been riding only about a year. I appreciate everyone's help.

I was using Orange II coolant which is designed for Dodge/jeep cars and minivans. I picked it at local hardware store because it said it was compatible with light aluminum engines and 1/4 price of the coolants in the bike specific shops.  

However shortly after using it,  I found I was leaking coolant out of the water pump weep hole between the seals after about every three rides (8hours)

I probably changed the water side seal 4 times. Finally frustrated, I discussed it local trials specific shop owner. He pointed out that the Orange II contained silicates which are designed to minimize rust, and are likely eating the seals. 

I switched to a dirt bike specific coolant, put on a fresh seal, and had no issues for about 5 rides until this recent fan issue...it could be related. However I was not seeing any leaks from the water pump area.

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