Frankeren wrote:Den syl som har hvit/grå plugg høres rett ut i allefall. Har akkurat kjøpt harley sjøl, så er ikke noen dreven motormann på harley. Men når alt kommer til alt så er en motor en motor. Usikker på om harley har to forgassere....?
Sakset fra XL forum
First off, forget everything you think you know from reading repair manuals because that only works on engines with old used plugs and engine problems that are easy for the average person to see on the plug without any special training.
Plugs can be read with as little as two laps on them at the track.
· Start with new, or extremely clean recently new plugs.
· Best readings are taken by running the vehicle at sustained speeds in the range that you are checking, IE: “Wide Open”, Mid Range”, “At or near Idle”, then disengaging the clutch, killing the engine cleanly, and coasting to a stop.
· Overall readings can still be taken without a clean kill and stop, even without new plugs. This is still very accurate, and one of the best tune up tools you have. Just make sure that you have good plugs and by keeping an eye on them as you make changes you can read the effect that the changes made. This just requires a mental track record or a written one.
Where to read them.
· The porcelain is used for reading plug heat range, and timing only. Never try to read fuel mixture off the porcelain.
· The inner wall of the metal shell extending down to where that meets the porcelain is where you read the mixture.
· Engine problems such as oil consumption, etc., are read by going back to your manual. We are only concerned with a good sound engine for fine tuning purposes.
How to read them.
· Timing that has too much advance will show as black flecks on the porcelain. These are flecks of aluminum off the piston due to detonation. Even a good running engine will show signs of minor detonation, but keep an eye on those flecks and if they get bigger and more of them it’s time to look seriously at the timing.
· To determine heat range of your plugs look at the porcelain as it starts to take color. If the porcelain is white to a light tan, the heat range of the plug is right. Remember we are talking a couple of laps so it doesn’t have much time to take color which is why white is acceptable. If it starts looking gray or black possibly even a bit wet looking, the plug is too cold. The more black it is and the more it is wet, the further to the cold side it is. If the plug is dark tan or worse yet getting a burnt black look to it with blisters on the porcelain, then it is too hot a plug. Note the difference between a cold black and a burnt black at the two extremes. They are not the same black by any means. Fuel deposits on older plugs flake off, so don’t confuse that with blistering.
· For reading mixture, read the metal inner wall ONLY.
· The upper ring around the electrode area (as you hold the plug electrode up facing you) is where you read the idle mixture. Correct reading is MEDIUM GRAY. Light gray to whitish gray is lean, dark gray to black is rich, with powdery black being richer yet, then after that it starts to get wet and the black gets flushed off like it was rinsed with gas. (You will see some of this on the intake valve side of the plug and that is not a concern if the color is correct otherwise).
· The lower ring where it meets the porcelain way down inside (you need a magnifying glass and good lighting to see clearly down to the bottom), is where you read wide open throttle. Color readings are the same for all ranges except that the wet flushed off look is only going to be showing at the idle portion of the plug.
· The mid range is everywhere in between that top ring and the bottom ring. Color is again read the same.