Machine screw type on choke lever

[BrianDowning]

Thank you all for your responses. All suggest were quite relevant. Unfortunately I couldn't find a 90° choke that would definitely fit. So while the best solution appears to be replacing the combined brake and choke levers with separate levers, the cost would be over £60.

I opted for a simpler inexpensive fix. Using strips of rubber adhesive flashing (yes, roofing material!) I was able to raise the lever higher so it would clear the throttle grip assembly. I needed slightly longer screws. They turned out to be 3/16 BSF. Not sure if my levers are original though.

Cheers, Brian