I had the bike for about a month now & very happy with it I have noticed though that the fan hasn't come on yet. I've been out about 5 times in fairly chilly weather but the fan has yet to come on. Any ideas is this normal for a beta.

5 hours ago, lonewolf said:

I had the bike for about a month now & very happy with it I have noticed though that the fan hasn't come on yet. I've been out about 5 times in fairly chilly weather but the fan has yet to come on. Any ideas is this normal for a beta.

A faulty thermostatic fan switch is one possible reason for a fan not running and very easy to test for by bridging the switch with the motor running.

It will be the thermostat   Good idea to cable tie a bridging wire to the plug under the seat  just in case it fails again in the middle of nowhere 

10 hours ago, feetupfun said:

A faulty thermostatic fan switch is one possible reason for a fan not running and very easy to test for by bridging the switch with the motor running.

Where do I bridge the fan. I'm terrible with electrics.

remove this cover

Starting from the thermo sensor on radiator, trace the wires back to the connector under the cover you just removed.  

Fab a jumper cable and disconnect the connector.

Start bike up and plug jumper into the connector end that is coming from the CDI box near the carb area. If fan does not turn on the fan and/or thermo sensor might be in need of replacement 

 

 

 

 

Edited February 10, 20233 yr by PAULIE

4 hours ago, lonewolf said:

Where do I bridge the fan. I'm terrible with electrics.

Jump a wire between the 2 leads that connect to the temp sensor on the radiator that come from the fan. Fan should run (while bike is running). If fan doesn't run when you jump the 2 wires, either the fan stopped working, or it is wired incorrectly. Mine had same issue and I discovered previous owner had for some strange reason wired in a kill button (ok), and then proceeded to wire kill ground wire to yellow hot wire from the magneto thereby grounding out any DC powered accessory  which was the fan on mine. You DO want the fan to run on a trials bike nearly all the time after engine gets up to temperature as low speeds and small radiators are involved.

Joe

1 minute ago, PAULIE said:

remove this cover

Starting from the thermo sensor on radiator, trace the wires back to the connector under the cover you just removed.  

Fab a jumper cable and disconnect the connector.

Start bike up and plug jumper into the connector end that is coming from the CDI box near the carb area. If fan does not turn on the thermo sensor is probably bad.

 

 

 

 

I would think that "if the fan DOES come on", then the thermo sensor is bad.

Jor

With a cold engine, when I plug the jumper into the connector fan comes on and when unplugged it turns off.  With engine warmed up it works as it should cycling on and off so it seems good. 

Edited February 10, 20233 yr by PAULIE

32 minutes ago, PAULIE said:

With a cold engine, when I plug the jumper into the connector fan comes on and when unplugged it turns off.  With engine warmed up it works as it should cycling on and off so it seems good. 

Correct.......you know your thermo sensor works and fan comes on as it should when engine warms up. You can also manually turn on the fan with jumper so fan works, and thermo sensor works. O.P. Lonewolf knows his does NOT turn on when hot, but needs to narrow it down to fan, thermo switch, or wiring. To verify if thermo switch is culprit, he needs to jumper wire and if fan DOES come on, we know wiring and fan are good but thermo switch is bad. If when he jumps wires the fan still does not come on then it still could be 1 of the 3 being bad ( fan, wiring, switch). He then needs to remove fan and apply 12v to it via a battery  and if it works, then we know it is a wiring problem. Wirie to the fan should be in the wiring schematic for his year Evo and needs to trace and verify.

Joe

Thanks for your help on this matter miles clearer now. I'll try jump the thermo switch over the weekend. I'll let yous know my findings. Any wire should be good to jump the switch yeah.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Hi again

Right this is what I've done so far

 I can't start bike at moment as carb is off waiting for an idle screw(shop sent wrong one so taking longer than expected). I've disconnected the fan connectors & put a 12v power supply to the fan & it comes on.  So the next port of call when carb is on & bike is running do the same again but bridge the fan switch connector & that should confirm that the wiring is correct. Then if that's the case it looks like the thermo switch in the rad is this correct?

2 hours ago, lonewolf said:

Hi again

Right this is what I've done so far

 I can't start bike at moment as carb is off waiting for an idle screw(shop sent wrong one so taking longer than expected). I've disconnected the fan connectors & put a 12v power supply to the fan & it comes on.  So the next port of call when carb is on & bike is running do the same again but bridge the fan switch connector & that should confirm that the wiring is correct. Then if that's the case it looks like the thermo switch in the rad is this correct?

Yes. Fan works so if bridging wires also activates fan then it's the thermo switch. 

Joe

Hi I think the problem is solved. Started engine ran for 5 mins, bridged the connector for thermo switch. Fan came on. So was looking like thermo switch goosed. Plugged connectors back in fan then came on by itself. Looks like dodgy connectors. Cleaned them up as best as I could & gonna use dielectric grease on them.

Cheers for all your help.

Well that was easier than mine. Turns out previous owner decided to connect kill switch ground wire to the positive yellow lead from the magneto (???).....effectively grounding out any D.C. accessories. In my case this was the fan, which never came on when I first got it. Took a bit to figure out and then fix. Good as new now.

Joe

Hi, my fan is also not coming on , I have put power to fan and it comes on , so not fan, have bridged the wire from the radiator switch and fan doesn't come on, any advice would be appreciated. L