How to warm up a motorcycle engine

Honda VFR800 VTEC engine with variable valve timing

Have you ever seen, heard and smelt a rider revving their motorcycle engine or idling their bike for minutes before getting on and riding away?

It’s obnoxious at a cafe when you’re trying to sip your latte amid their fumes, but it’s also fairly pointless and a waste of fuel.

It may also be doing their engine harm if they don’t warm it up correctly.

Old motorcycles with carburettors and gluggy oils required a long period of warming up but surely today’s fuel-injected engines with modern synthetic oils can go straight after you push the button, right?

Yes, but it also depends on how old the engine is.

If it’s a new bike, it will require a few seconds – not minutes – to warm up. This is not only so the oils warm, but so the gaskets and valve seat properly in the new engine.

After the first 1000km, you won’t need to warm it up for near as long, if at all.

RACQ technical guru and Suzuki Bandit rider Steve Spalding advises riders not to idle their engines any longer than is necessary.

“At traffic lights, it’s unavoidable but there is no need to run at idle before starting off,” he says.

“The best advice is to start the bike and ride away as soon as it will do so without any spluttering – in Queensland’s climate this should be almost instantly almost all year round.”

Modern engine management systems will ensure the fuel mixture is correct unlike the days of setting the choke on the carburettors to allow smooth starting from cold. And modern synthetic oils get the oil flowing quickly to lubricate the engine, even in cold conditions.

In fact, oil pressure rises when the bike is under load, so it is actually lubricating the engine better to be moving than sitting still.

If you idle modern bikes too long, or rev them hard before riding away, you can do long-term wear and damage to bearings and seals.

Honda CX500 motorcycle engine

As for old bikes like my 1980 Honda CX500, let them idle with gentle revs not exceeding a third of the revs to redline. Allow the choke to slowly go back in with a gentle prod, however you can head off before the choke is fully off.

Just make sure the engine is running smoothly at idle and not conking out. Don’t just rely on the engine temperature gauge or feeling the fins of the engine.

Once underway, don’t leave the choke out for too long as this can carbon up internal components such as valves, piston crown and rings and it makes the bike blow black smoke.

The time it will take to get an old engine running smoothly will depend on its condition, displacement and configuration as well as the ambient temperature.

8 Comments

  1. At idle
    – lower oil pressure
    = reduced oil flow to overhead gear (cams valves etc)
    = oil circulates more slowly & takes longer to warm up

    – lower combustion chamber pressure
    = rings, which rely on high combustion chamber pressure to force them out away from piston grooves & against the cylinder wall to provide a good seal
    don’t seal as effectively
    allowing combustion chamber gases to get past rings & dissolve in the oil.
    That’s why a vechicle used only for short trips will have a drop in oil level if driven on a motorway for an hour. The dissolved contaminating gases evaporate out of the oil.

    Stationary engines (pumps, generators, lawnmowers) are designed to run at constant speed.
    Motor vehicle engines are not.

    Automotive engines rely on varying engine speeds & throttle openings to properly lubricate cylinder walls & piston/ring group
    as well as maintain high oil pressure & flow.
    That’s why the lowermost ring is an oil scraper ring.

    Turn engine off if stationary for any length of time – gets too hot + reduced oilflow.

    Warm up – ride off as soon as able without stalling = immediately on modern engines
    take it gently until warm.
    Best advice is to read owner’s manual re running in new engine, & do that until engine is warm.

    Don’t warm up your engine 5am at the motel I’m staying at
    for your sake, not your engine’s.

    1. When travelling & entering a town, observe speed limits.
      Reduced engine speeds for a minute or so enables engine temperature to drop before shutdown.

      Internal engine temp soars immediately after shutdown
      because coolant & oil circulation, as well as aircooling, abruptly cease.
      It’s been measured because it can be a problem in racing when a vehicle pulls into the pits.

      Warming up at idle is feelgood bullshit.
      Gentle cooling down for a minute with vehicle moving before stopping is a good idea – when possible.
      Letting your engine idle for long periods when stopped
      in order to run the aircon
      wears it out.

  2. If riding an air cooled bike I perform no warm up at all, as the motor will heat up faster sitting than it will riding, so I believe riding will warm it up more gradually than sitting, and therefore be easier on the engine.

  3. Most modern fuel injected bikes have an auto choke. Riding while it is on can be a challenge as the revs are higher than in a car making gear changes painful and requiring a good degree of attention. A modern engine should be able to cope with idling until the auto choke switches off at which point it is safer and more enjoyable to ride off.

  4. My 2010 Can Am Spyder RSS (Rotax V’Twin) has over 110,000km on the clock and most mornings it fire and run, I have a few corners before I can consider opening the throttle, same applies if I decide to take my 2010 Triumph Speedmaster (146000km) and at 4:30am you want to keep the neighbours on your side!

  5. The manual for my 07 BMW advised not to idle at all & says to be aware that the engine requires air cooling which may be an issue if the engine is running while the bike is at a standstill

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