Why is it recommended to warm up motorcycle engine before using it?

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I don’t know if this is the case for cars since i don’t have one. But driving a warmed up motorcycle is definitely a lot better than just driving it straight away

In: Engineering

The short version is that things get stiff and clammy when they’re cold: The fuel is more sludge-like, the oil is a little less viscous, the mechanical cams and valves in the engine itself stick a little bit, and so on. Allowing the engine to warm first helps it operate more smoothly, consistently, and handle the load of propelling the motorcycle more gracefully.

EDIT: This is also because metals expand as they warm up. The engine’s parts are engineered to fit best at running temperature, so you get best performance (and reliability) if you let the parts expand to their “running” size before putting any load on them.

When an engine is cold, the air/gas mixture going into the cylinder will allow the gas to condense on the cylinder wall, leaving the engine in a “lean” condition, which is why you had to choke old engines (fuel injection doing the same thing, but automatically). So now there is liquid gas on the wall of the engine washing away the protective oil coating, causing metal to metal contact rings to wall. Additionally, there are numerous corrosive gases generated by the combustion process that will burn out naturally at normal temperatures, but are very evident when cold. All of which adds to initial wear on your engine. I read that the start up process adds more to your wear than the rest of the day’s driving, but have no corroboration on that.

Motorcycles have the same problem, with the possible added problem that they usually run at a much higher rpm and could presumably do mire damage more quickly.

“warming up” is somewhat of a relative term..

firstly your motorcycle engine probably contains, at most, about a quart of oil. if even that much. you car however, probably has 3-4 (or if it’s a modern high performance car, more like 8-10) .. so a motorcycle will take significantly less time to “warm up” all it’s oil… in most cases that time is right around 30 seconds. significantly less if you’ve got the choke on.

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secondly, unlike your car, your motorbike uses the same oil for the gearbox and the rest of the engine, so the oil is doing significantly more work.

oil performs significantly differently when it’s cold, compared to when it’s warm.. you may notice your oil has a rating on it, like 5w10.. the two values are *roughly* the viscosity ratings when the oil is hot and when it’s cold (w traditionally means the “winter” rating).

so trying to force an oil around the insides of an engine and gearbox when it’s more than twice as thick as it can be.. especially when you can just wait 30 seconds to get it up to temperature.. means that the engine isn’t getting it’s full protection and lubrication that it could be getting.