The gap according to Dave on his Roadster is max 2mm although I think he aimed for 1mm. Dave's full article for axle mounted speed sensor (assuming same for Plus 4) minus working pictures here.
Scroll down to get the images!
Thanks Dave - link on my original post ammended accordingly.
Richard
2018 Roadster 3.7 1966 Land Rover S2a 88 2024 Royal Enfield Guerrilla 450 1945 Guzzi Airone
