I have used a Champion RJ19LM or J19LM, both work fine.
.30
.030
rj8 is used for a 7hp Tecumseh that powers a 22" yardman snowthrower
According to my owners manuel the spark plug gap is 30
My book for my John Deere snowblower , which has a 5 horsepower Tecumseh engine , shows to use the Champion RJ17LM spark plug
.030"
J19lm
The correct spark plug for a 5 hp. Tecumsen 4-cycle motor is Champion J-8 (RJ17LM). The plug gap is 0.030 in. (0.76 mm)
Tecumseh website, "All spark plugs air gap is .030."
Per Champion spark plug applications chart, the gap for 6hp Tecumseh engine is .030
The Answer to your question RJ19LM spark plug set at 20 thousand of an inch.
Call any auto or small engine repair shop they will have books on that info!
Impossible to answer, depends on what model KTM you have.