Dirty Deeds...

Done dirt cheap… CMM reader Keith Dickinson restores and rebuilds Honda’s CRM250 AR.

- Keith Dickinson

When I first got bikes we used to go off-road quite a lot. However, my Casalsports moped and later a Honda CB175 were not much use compared to some of my mates who had pukka off-road bikes!

I had always hankered after a proper off-roader, but it was not until I got to 47 that I managed to scratch that particular itch. It had to be a twostroke, and preferably an interesting one to complement my RG500. A search revealed that the Honda CRM250 was generally considered to be the best road-legal dirt bike from the 90s. The bikes were never officially imported into the UK, but many were brought in by Leisure Trail in Nottingham and are quite common.

The last of the line was the Active Radical (AR) version, which was Honda’s last attempt to clean up their two-strokes using technology pioneered n their successful EXP-2 (440cc) Paris-Dakar race bike. The technology was claimed to clean up the bike so that emissions and economy were comparable to an equivalent four- stroke. This was achieved using a modified exhaust valve that increased compression markedly when fully closed. In fact, compression is increased so much with the valve fully closed that autoignition/detonation occurs triggered by free radicals and the bike will run without a spark.