CLASSIC TECHNIQUES

I rebuilt a 1959 Matchless G12 in 2012. It would not idle properly and the worn-out Amal Concentric quickly went out of tune. Eventually I forced myself to buy a brand new Monobloc from the AJS&MOC. I had been mucking about with that old carb for ages and fitting the new one was so easy, and it idled like a clock.

Eight years later, and very gradually the bike’s tickover has become more and more erratic. I re-set the slow running mixture screw but eventually it just had no effect. The bike