Hi there. In a competition today my 04 Beta Rev 250 started to boil. Steam was flying out of the valve at the top of the rad on the final lap and I had to retire or face a costly siezure. I thought the thermostat may have gone again (I replaced it six months ago), so I bypassed it and the fan still seems problematic. Even with the thermostat bypassed the fan seemed intermittent and doesnt seem to spin with the same speed it use too. I suspect that the fan is the problem but why when the thermostat has been bypassed does it not come on permenantly and why is it spinning so slowly. I would be gratefull if anbody could shed some light on this.

I had a fan fail on my Techno. It was a japanese one and I found a second hand replacement from my local bike wreckers from a ZZR 250 kawasaki or something like that. It might pay to check and see if you can revolve it easily by hand. If not chase up a new one. The other thing I found (with the Techno at least) was that the stator was supplying the fan with over 50 volts at times. I fitted an aftermarket regulator to keep it at 12 volts and it has been good so far (2 years now).

HTH,

Cheers,

Stork

I had a fan fail on my Techno. It was a japanese one and I found a second hand replacement from my local bike wreckers from a ZZR 250 kawasaki or something like that. It might pay to check and see if you can revolve it easily by hand. If not chase up a new one. The other thing I found (with the Techno at least) was that the stator was supplying the fan with over 50 volts at times. I fitted an aftermarket regulator to keep it at 12 volts and it has been good so far (2 years now).

HTH,

Cheers,

Stork

Thanks for that advice. I too think it is the fan that needs replacing. I have not taken it off before but it looks like the radiator will have to come off in order for me to access it. Any ideas ? As the bike is five years old I was thinking I may replace the hoses whilst I am at it too.

Gday, Im not sure about the Rev 3 but you certainly do on the Techno. I Imagine its fairly similar and not a major job. It would be easy to check hoses while you are in there, if they feel "crunchy" or very soft they need replacement however mine are nearly 10 years old and still in good shape.

Just a thought as well, you can check the fan by jumping 12 volts straight to it from a car battery or similar. It should spin up quite quickly and run without getting hot to touch while pushing out a fair gust of air. Might be an easy way to further check it before removal. And, is the radiator nice and clean in the fins to allow good airflow?

Cheers,

Stork

Yes check the fan as stork said further to that it will be a check of the wiring loom

and then possibly the generator to check the output is sufficient and stable!

Thanks gents. ran 12 volts through fan and it worked fine. Checked thermostat and that is fine. So it must be the voltage regualtor. Have ordered one so I will wait to see how it goes. Just one of the rad pipes looked a bit dodgy so I've changed one of those too. Cheers. gaz

I have the same issue with my Rev 3 250 2002 - i have joined the thermostat wires and still no life with the fan - going to try to check with 12 volt battery - how much are the voltage regualtors?

any ideas?

Lee

Hi,

I would advise you to clean correctly (no high pressure!) the radiator, in the case it would be too dirty, there will be no air to pass through, so the fan can be damaged by overheating.

Tae this message as an advice, it can be the source of your problem, not the solution.

Kr

Jeremy