Speedmaster - Even more Spitfire.

Take one bottle of  Spitfire Ale.

Drink the bottle till empty. Put empty bottle in recycle bin.

Take the cap. A stainless steel bolt and a large washer. Attached the cap to the washer. Peen over the edges of the cap around the washer which has the stainless steel bolt through it.

You now have a hand made choke knob that cost around $10.

Take the bike's choke knob off. Fit the one you have just made.