Hi. Forgot to say I have only checked the Honda fan direct from a battery. Will try on Gas Gas tomorrow to see if it will spin up in both directions. Did check my Beta Rev 3 fan this aft and it spins anti clockwise. Fan blades on Beta seem to be same orientation as Gas Gas so I guess the fan should spin anti clock and therefore suck rather than blow! Hey ho!

Bill

Hi, Although I asked the question I am not sure what is the right answer. I would assume the fan sucks air through the rad, I will have to check mine when I get it out next.

TLTEL

Yes, to both questions:

1) the fan should suck air through the radiator. That way when you ride forward the air movement will still be from the tire side toward the engine.

2) the fan motor should spin clockwise when the wires are connected one way and counterclockwise when the wires are reversed. That is why there is a rectifier bridge to convert the alternating current to direct current so the fan spins the right way.

When the rectifier fails, it could let full or partial alternating current to the fan. AC will make the motor shudder and not spin. Partial failure could cause the motor to run in one direction but not well. Depending on which leg of the rectifier fails, the fan could turn in the proper rotation or in the reverse rotation.

I am 99.5% confident that is the problem with WildBill's bike - a failed rectifier. I am waiting to hear how it works out for Wild Bill.

Hi That's a five.

Fitted a second hand fan from a Honda 125 today and this motor will spin CW and ACW on Gas Gas with engine running, depending on which way round connectors are fitted. Having stripped both Honda and Gas Gas fan motors from their respective mountings, they both have a directional arrow on the label on motor body that shows the motor should spin ACW. Motor functional - One problem solved!

Am liking your latest diagnosis re partial failure of rectifier, although new motor will spin quite happily both ways whereas the original motor would only spin CW. Now I will recheck voltage across the new motor for both DC and AC and look to fit a new rectifier if reqd.

Bill

Hi.

Mounted and secured new fan motor with fresh connectors and all earths cleaned. Started bike and on idle fan turns over quietly and steadily in ACW direction and the voltage across fan wires is reading a more realistic 12.3v DC (with a faint reading on AC of 1.2v). It would seem that the problem is now resolved so I can only think that it was a combination of a dodgy fan motor and poor cable connections and corroded earths.

Getting old doesn't seem to be good for the bike or the rider!

Thanks for your help

Bill

Great News Wild Bill.

As someone's signature says "Don't stop riding because you get old, you get old because you stop riding."

Feet up!