This subject refers to GX390 OHV Honda Engine Copy done by Lutian China commissioned upon 5.5KW portable generator.
I have not long ago transposed a Head Gasket due to a tiny oil trickle in it as it was burnt due to crude hanging ornament upon a singular of a 4 conduct bolts. Under Load a generator used to onslaught a bit. The deputy gasket was a bit thicker than a a singular which came out. Hence we additionally practiced valve clearances to 0.20MM money coming in as well as 0.25MM empty as per primer (with engine cold at room temp). The engine as well as a generator ran a lot smoother than prior to for we estimate thirty hours with alleviation in fuel manage to buy as well as no leaks. Tested a engine underneath bucket as well as it runs a lot smoother than before. There is no complaint with starting, it starts instantaneously. Spark Plug we am regulating is NGK BKR6E-11. Now when we spin off a generator after an hours make use of underneath bucket as well as when a engine has come to a finish stop after a second there is regularly a singular single behind glow with glow from a exhaust. we have attempted Using NGK BP6ES hint block though behind glow continues. we consternation what is causing this? Can It lead to engine damage? What to check as well as how to repair this? As this shrill cocktail is utterly irritating.
#1 by JD on June 29, 2010 - 11:43 pm
When you shut down the engine you are stopping the spark to the plugs. You should not be backfiring when you hit the kill switch.
When you replaced the head gasket, did you check for carbon buildup on the top of the piston? If there is carbon buildup on the piston, it can get "red hot" from long-term use, and it will ignite any fuel left in the cylinder regardless if there is spark. This would explain the backfire after a long day of running.
Take out the spark plug and shine a light down the hole. If the piston is black, you have carbon buildup. If it is metallic, it’s something else. Carbon buildup can lead to detonation and yes, permanently damage your engine.
#2 by pedro7of9 on June 29, 2010 - 11:43 pm
exhaust pop is caused by heat and fuel….check needle valve and float in carb..don’t know if valve change has effect..maybe not closing all the way…
#3 by LeAnne on June 29, 2010 - 11:43 pm
This isn’t unusual at all – especially on a hot engine. The spark is cut off when you initially shut the engine down but the residual fuel is still in the manifold and it may or may not ignite in the combustion chamber when the engine is turned off. Bring the engine to an idle if this is possible on this model before shutting it down – this will minimize the problem.
Nothing serious will result from this.