Tecumseh BVS 143 (Mountfield Empress) - Won't start, oily spark plug, stiff jerking pull

[tadawson]

The idle *mixture* screw sets at one turn out initially (if this engine has one) - that's not the same as the idle *speed* screw.

 

[Carvelosbvs143]

Hi bit late to this one but you mention the engine is jerky to pull over but smooth with the plug out. It will be as engine compression makes it jerky. With the plug out the engine has no compression so the piston is free to move up and down without the influence of closed valves and a volume of air being squeezed in the cylinder. Think about old British motorcycles' reputation as being leg breakers, Same thing with a mower but less chance of going to the Ace cafe