Note:

Quite a few 2C engines in the .50 and up range will benefit from a "long" plug, when the engine is mounted inverted...

Long plugs are also included with many 2C engines as well, and newbies often exchange them for shorter plugs as per the recommendations here are RCU, which in turn can cause problems with previously well running engines.

As a "for instance" Supertigre .60 and .75, and most of the Evolution engines include "long" plugs in the package....



From left to right: Stock Evolution 1.00NX 2 Stroke Glow Plug O.S. "F" 4 Stroke Glow Plug Stock SuperTigre .75 2 Stroke Glow Plug O.S. A3 2 Stroke Glow Plug