Originally Posted by
jnc011994
Hello Sir,
I too have the same issue, I have GO .21 7 Port, and I do stop the motor by blocking the exhaust port. But i still have "burned" (I mean, really, really black) glow plugs. I have only use OS A3 plug. Would you suggest OS 8 plug?
Thanks,
Jojo
Plug colour is generally caused by tune and the ash content of the oil in the fuel. these are the 2 main things that cause plug colour. Black is generally a sign of it being a tad rich , it is also a sign that the fuel may have a dye that burns and bakes in the combustion process. what does the piston top look like ?