WHAT TO LOOK OUT FOR

The B31 can be mechanically reliable and the engine design doesn’t really have any defects. The brakes on the early B31 can be a little feeble for pulling up all that weight, but those fitted to later models are acceptable. Lighting can be feeble, especially on the dynamo-equipped models, and will benefit from fitting good LED bulbs. If you are checking one with a magdyno out, make sure the dynamo is charging by checking out the ammeter. Just because it starts doesn’t mean it will keep going, as the magneto might work initially but can break down if the longevity of the windings is suspect. Ask if the mag has been overhauled, ask to see a receipt, and expect to pay £400-plus to have the job done if it hasn’t.