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If I have a motor vehicle as a general question,

Is warming up the engine for a short period of time - let's say 5 min, is it a good thing for the engine or bad?

and what about specific for this bike: 1998 Honda CBR 918RR Fireblade?

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  • When in doubt, what does your owner's manual say?
    – dwizum
    Jan 6 '20 at 21:23
  • good point and here is a link to the manual of a similar bike Jan 7 '20 at 9:14
  • actually I am not sure how similar as this bike is 2008 Jan 7 '20 at 9:17
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My Kawasaki owner's handbook stated that it should not be idled for more than 5 minutes when started. However the dealer advised me to let it warm up for a few minutes (by idling, not revving), especially in cold weather. Partly so the oil can warm enough to circulate freely, and because of tight engineering tolerances in machined parts, which are not correct when the engine is cold, and without proper lubrication too, there is a danger that the engine might seize if you drive away too soon – with worse consequences on a motorcycle than in a car.

So I would start the bike's engine, push the choke half way back if it had been needed, look the machine over, put on my helmet and gloves, zip up, cancel the choke (or within half a mile when cold) and then ride off gently. That approach also settled me into the right frame of mind for riding, no bad thing.

Apart from that, I believe a motor vehicle should be started and driven away gently after a few seconds, as the best way to warm it up and to allow circulation of the lubricant. In cold weather you might want to wait a few minutes for demisting or ice scraping, and you can't drive away before the window glass is clear anyway. But again, never rev a cold engine.

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For a late model car, you want to start it, buckle up, turn on the heater, radio and then drive with a light foot. Warming up a late model car warms the coolant, but not the oil. The fastest way to warm the oil and increase oil flow it to drive it, not idle it. See this post

https://ricksfreeautorepairadvice.com/warm-engine-winter/

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We "warm up" vehicles for a number of reasons:

  • An engine that has sat will have had some degree of drain down - the oil will have drained off all the critical moving parts and won't be able to provide any protection until the oil pump has run for several seconds. Also, cold oil is thicker and has different properties than warm oil. Getting the oil pumped through the motor only takes a few seconds, so it's a good idea to let a bike idle for at least a few seconds before you move off. Once you're moving, the oil will naturally warm enough to thin out within a few minutes of gentle driving - it makes sense to not push the bike hard until this has happened.

  • Fuel doesn't atomize well when cold and when being sprayed into a cold engine. This can show as rough running when the bike is cold, or even a motor that won't start or won't keep running when it's cold. Modern fuel injected bikes will compensate for this automatically (usually by changing the mixture until a certain temperature is reached, or by adjusting other parameters). Really old bikes will have a choke on the carb to let you manually compensate for this. Early fuel injected bikes sometimes just brute-forced this issue by always being slightly off ideal settings under conditions where fueling might be marginal. If you're following the advice above about taking the first few minutes gently, this will likely be a non-issue even in a bike that doesn't automatically compensate. By the time you've ridden a few minutes for the oil to warm up nicely, the fuel system will be operating just fine.

  • Tolerances for mechanical parts within the engine will change as they heat up. This is arguably less of an issue than people sometimes make it out to be, and once the oil has pumped through the motor, it basically doesn't really matter, especially if (broken record!) you're riding gently for the first few minutes.

So - letting the bike idle for a few seconds is probably a good idea, in general.

That leads to a natural question: are there any reasons why letting a bike idle can be bad? High performance bikes are typically very highly optimized to work well under high performance conditions. This can influence answers to this question in a few ways:

  • A bike that doesn't have sophisticated fueling management for different idle conditions and temperatures may be rich enough at idle once warmed up that it will slowly gunk itself up with fuel deposits if it's left to idle all the time. This can manifest in dirty valves and other issues over time.
  • A bike with a cooling system designed to work at high speeds may be marginal in terms of cooling the engine at idle. This can manifest as really hot coolant and oil temps at idle (especially in warm climates). Running really hot is obviously not very good for any engine. Even if not damaging for the bike, this can be really uncomfortable for the rider since all that heat will just slowly cook you!
  • Idling more than required to get the oil pumping is, at the end of the day, a waste of time, a waste of a small amount of fuel, and extra pollution.

With all this in mind, to answer your general question, for a motorcycle, it's probably a good idea to warm the bike for at least a few seconds, but there is no real reason to idle for a long time, and doing so may have negative impacts - so, start the bike, let it run for a few seconds (maybe a minute in cold weather), and move off.

For other motor vehicles, the answer may be a little different - for automobiles, it's arguable that there's some minor benefit to several minutes of idling in very cold temps, since it can give the climate control system enough time to at least start heating the cabin up. This is obviously not applicable to motorcycles.

And, at the end of the day, the real answer for any specific vehicle should be to check the owner's manual, and follow any instructions there, unless you have very good reasons not to.

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