Timing lights aren’t connected to the engine while it is in actual use conditions, they are typically used in static situations with no load or rider error. If it is too early, the piston movement will be forced against that expansion and catastrophic metal failure of internal parts will commence.Ī timing light can’t detect pinging. If the spark comes at the correct time the flame front and resulting expansion will occur to push the piston when it’s on its way downward. Shifting down can quieten the noise, but the engine still may still be pre-igniting more subtly, which causes the internal combustion to react against the direction of the piston rather than with it. Pinging will be heard when accelerating in a gear that is too high or when when lugging up a grade or against a strong headwind or with low octane fuel or overly lean mixture or some or all of those combined. It can sound like a jingling keyring as well I use only a single key in the ignition to prevent confusion. Pinging is a high-pitched and subtle sound, often described as sounding like aluminum foil being crumpled. This leaves a little room for improvement if implemented with responsibility and vigilance. The marks are probably purposely conservative to prevent such possibilities. If the reference marks are improperly placed, different fuel is used compared to what was used to set the timing, and/or the atmospheric conditions change due to altitude and the rider does not recognise the sound of pinging or understand its consequences, the timing light method may actually contribute to the premature destruction of the engine. The goal of setting timing is to provide maximum possible responsiveness while protecting the engine from damage. And that placement was for fuel formulations from the 1970’s when leaded fuel was still available and ethanol was called Dry Gas and was used to remove water from fuel instead of what it does today. So the timing marks are probably in a safe-for-1960’s-manufacturing-tolerances, but not necessarily optimal, position. Loopframes are very well engineered, but the engineers didn’t build them, hourly assembly employees did, and in the gap between engineering and manufacturing lurk the marketers and bean-counters. On older engines, part and assembly tolerances were sometimes looser than they are now. The converse thought –harbored by the less-trusting– is that using a timing light requires all of the markings to be indexed precisely to be valid. Setting ignition timing without a timing light is considered by some to be inexact and dicey. It is very simple for a mechanically-inclined person to implement, but it also has the potential to damage or destroy an engine if performed improperly or without understanding the underlying principles. I have used this method with cars, trucks, and motorcycles with point ignitions for almost 30 years. The retired mechanic (Thank you, Ed Bickerstaff!) who taught me this many years ago called it “power timing”. The underlying principles invoked are similar for other engines. These have an external distributor with cap. This article was written with Moto Guzzi loopframe motorcycles –V700, Ambassador, and Eldorado– in mind.
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