RE: Thunder Tiger 130 Four Stroke
I've just finished replacing the head on my engine and i now believe there is a manufacturing flaw.
See the picture below of the head with stripped thread. You can see that the thread does not go all the way to the end of hole because of the angle of the combustion chamber.
The problem is that the threaded portion of the hole is not deep enough and the plug bottoms out on the end of the threads before the copper plug washer seats to form a good seal.
This results in a leak around the glowplug. I saw this during the first run of my engine and subsequently stripped the thread trying to get the plug to seat properly.
The new head i just to fitted my engine leaks around the plug too. Turning the engine over by hand was enough to force the oil i used during the re-assembly out around the plug and you can hear it leaking past the plug.
I tried two plug washers and it sealed well and no leaks.
How much effect on compression would 2 plug washers have until i can locate a tap to extend the threads?