Hello everyone.
This time I'll show you how I protect my regulator from heat.
I've written about it before (in Japanese): a regulator failure once left me having to abandon my bike and go home without it.
Replacing the regulator fixed that problem.
Since then, I take these two measures against regulator failure:
- Carry a spare regulator
- Cool the regulator
Measure 1: carry a spare regulator
For the spare, I think either a genuine part or a very cheap one sold online (about 2,000 yen) will do.
My spare is also a cheap one I bought on Amazon Japan. I always carry it so that I can swap it if the regulator fails on the road.
For reference, the genuine regulator part numbers for the Honda XR250 BAJA (the Japan-market XR250 / MD30) are 31600-KCZ-003 and 31600-KCZ-J71. When you choose an aftermarket one, I recommend checking that it is compatible with these part numbers before buying.
Measure 2: cool it with a PC cooling fan
For the other measure, cooling the regulator, I fitted a PC cooling fan (60 mm square, 12 V).
I took the power from the tail light wiring. The tail light is on whenever the ignition is on, so the fan keeps running while I ride.
On the XR250 BAJA, the regulator is under the seat (where the yellow arrow points above).
The photo above shows the fan fitted. It is fixed to the frame with cable ties (zip ties).
By the way, the fan isn't fitted to blow air onto the regulator, but to draw air away from it.
I've forgotten the model number of the fan I used, but here is a similar 60 mm, 12 V PC fan (for reference).
Result: even a cheap regulator has lasted over 7 years
In fact, this regulator is also a cheap one I bought on Amazon Japan for about 2,000 yen. But I've used it for more than 7 years without any problems (as of October 2026). There's no way to prove whether the fan is the reason it has lasted, but I believe it is.
Summary
I've shown how I try to avoid my bike breaking down from regulator trouble in the hot summer months.
I hope you find it useful.
Why I carry a spare in the first place: the story of my regulator failing on the road.