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Engine Warm Up Best Practice

Blog Date 12 June 2020

Most engine wear occurs on cold startup. There's lots and lots of complex technical reasons but in terms I can understand...

  • The oil has drained down to the sump and it takes a few seconds for the oil to get back around the engine.
  • The oil is cold and thick.
  • All the parts are cold and cold metal is smaller than hot metal, so all the parts are "the wrong size". 

There are plenty of other issues when starting a cold engine but these above will do for starters (ha!).

The tappets and valve train in the CBF125
You're going to want some oil at the top of the motor I reckon.

So what's the best way to minimise wear when you start your cold motorcycle engine? I'm afraid you're going to have to strike a balance. Ideally the faster the engine warms up the sooner everything is working as it should be. 

So then thrash it mercifully to get it warmed up as quickly as possible? Erm nope. Thrashing the motor while cold will just increase the damage to the cold motor. Take it easy? Erm, not quite. The longer the engine is cold the longer the torture on the parts. ARRRGH! We are trapped between a rock and a hard place.

An ordinary street with the cars and road covered in a thick layer or snow
Winter, remember winter? It's like summer but colder.

And now dear readers, it's that time again. We are venturing off into the dangerous deep dark murky waters of... (cue dramatic tension music...) OPINION! Opinions are like where your poop comes out of, everyone's got one and poop comes out. Never-the-less and I know you did not ask but here is my opinion on starting a cold motorcycle straight from my own misguided unpleasant parts.

1. Start the motor.
7. Wait for 15 seconds at idle to ensure the oil has had time to circulate.
4. Start to ride the bike taking it easy for the 50 metres of my back street to the main road.
2. Ride the bike normally but not aggressively for the first 5 minutes.

My hope is to firstly ensure the oil is flowing then strike that equilibrium between stressing a cold motor and letting the motor remain too cold for too long. 

There, I've said it. Now to stand back and admire all the various thoughts, experiences and tales from the readers. By all means share your opinions, your experiences, your mechanical know-how and your reasoning, but do let us be polite in expressing them.  

Ren sits on a beach wall looking contemplative and deep in thought
Hmmmmm... what amazing insights will I gain from the comments section?

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Reader's Comments

Upt'North said :-
One factor Ed that you didn't touch on is personal circumstances.
I would be quite happy for security reasons to leave the bike running outside of my house but probably wouldn't want to leave it out unaccompanied in some locales. Someone may for instance have to close gates, wave goodbye to their loved one, put the V's up to the neighbours etc.
But of course unless there were unusual circumstances, such as Er'Indoors going back inside to get her comb(?) I wouldn't leave it running at all. No modern engine in a road vehicle requires a warming up period. More wear is caused the longer a vehicles engine is below normal operating temperature and the quickest way to warm an engine is to drive it.
Some murky corners of the Internet will tell you that carburettor engines should be warmed, which is complete nonsense; carburetted engines should be adjusted correctly so they run well on choke which should be off ASAP to prevent washing oil off the cylinder walls.
Start it.
Ride it.
But a little mechanical sympathy for the first mile would be good.
12/06/2020 08:46:06 UTC
Ren - The Ed¹ said :-
If my key is in the bike I'll be within 5 feet of it. It's pretty safe around here but I still wouldn't leave the bike running without being right by it. My home routine is to get the bike into the back street then start it, leaving it for the 15 seconds it takes to lock the gate and get on board.

If you were to start your bike then go inside to get your helmet and the bike was stolen, the insurance wouldn't pay out and I seem to recall it's illegal to leave a vehicle unattended while running.

The highway code in the UK states...

123.You MUST NOT leave a parked vehicle unattended with the engine running or leave a
vehicle engine running unnecessarily while that vehicle is stationary on a public road.
Generally, if the vehicle is stationary and is likely to remain so for more than a couple of
minutes, you should apply the parking brake and switch off the engine to reduce
emissions and noise pollution. However it is permissible to leave the engine running if
the vehicle is stationary in traffic or for diagnosing faults.
Law CUR regs 98 & 107

12/06/2020 09:08:00 UTC
Upt'North said :-
Unfortunately Ed the highway code does not account for piddly motorcycle batteries where if you stop it and restart it more than twice you won't be starting it again. Plus obviously the more you stop and restart the engine the more you intensify cold start wear.
Some folks are not fortunate enough to be able to ride it out the front and be away.
I'm thinking bikes parked in sheds at the back, bikes that have to be manoeuvred through alleyways with the engine running etc.
I would generally not leave keys in any vehicle but I'm spoilt, although I'm quick to learn when away from home.
12/06/2020 09:16:34 UTC
Bogger said :-
I start mine and leave it to idle for half a minute, then take it easy for the first 3 to 4 miles then we're away.

Who really knows what the best course of action is?

12/06/2020 10:12:40 UTC
Ren - The Ed¹ said :-
Upt - Yeah say you have a steep slope up which the bike needs the engine to get it out on the street, you'd need the engine for that. Then you'd have to switch off to get kitted up etc. All I can say if this is the case do your best to be "ready to ride" once the motor's started. I accept this isn't always possible though.

What worries me are cars/bikes that have been in the dealers for a while. Start the engine, move the vehicle across the showroom, stop the engine. Or those lots where they drive the cars out to display in the morning, inside for overnight storage.

Bogger - I'm sure there'll be scientists who've researched this in great detail. However I'm sure the various different studies all came up with different results. Different engines, different oils, different climates, different procedures, different methods of measurement... Science is science but the universe is a very very complex place with almost infinite variables.
12/06/2020 10:40:30 UTC
Snod said :-
I tend to wait at least until the tickover has settled down to somewhere near where it should be, with the choke off. My old CB250 refused to run on the main jet until it was at least close to warm so sometimes you don't even have the choice! Sometimes a choke can be too fiddly to work with gloves on too, so there's at least a short time when you're still kitting up while it's running.

The only bike I don't warm up is the K100 and that's because the owners manual specifically states not to do so, just start it and ride away. If you leave them running supposedly you can cook the crank sensor, though I don't understand at all why I can instead sit on it in traffic when it's all good and hot.
12/06/2020 12:11:42 UTC
Bob said :-
Anybody remember the choke on an 80s or 90s Kawasaki?
Start from cold and you either had the choice of 4000 RPM or nothing!

Cold starts are another area where I think EFI does it better. On the KLX it starts and goes straight to a cold tickover of 2000 RPM and it will stay there for a minute or two until the engine begins to warm.
My routine is not far off Ren's, I'll start it up and roll it onto the street, then it warms whilst I lock up and put my helmet on (it's quiet round here so I have no worry about it getting nicked).
By the time I set off it's probably had a minute or so of warm up.
Then I take it easy for the first 2 or 3 miles, the bike lets me know when it's warmed because tickover drops down to the normal warm tickover.
12/06/2020 02:13:14 UTC
Ian Soady said :-
Start up the straight out on the road, taking it easy till the oil warms up - say 5 miles or so.
12/06/2020 02:14:05 UTC
Ian Soady said :-
Then not the of course. When are we getting an editor ed?
12/06/2020 02:14:43 UTC
Ren - The Ed¹ said :-
Ian - I'll finish off what I've started just for you... when I've got all this other work done!
12/06/2020 04:01:24 UTC
Bogger said :-
Mr Ed where was that photo taken please?

12/06/2020 08:38:13 UTC
Ren - The Ed¹ said :-
If you're referring to the beach shot, Salcombe. If you want the details follow the link...
12/06/2020 08:59:38 UTC
Bogger said :-
Thanks. I thought it looked familiar.


12/06/2020 09:31:04 UTC
Ren - The Ed¹ said :-
I take it you've visited there yourself at some time then. Pretty little place.
13/06/2020 08:30:51 UTC
Bogger said :-
Yes. I've been to the area many times. My favourite place in Devon is Brixham. I've got a couple of mates that moved down about ten years ago.

When I was very young, a long time ago, we used to stay at Goodrington sands in my parents touring caravan. So we used to visit Brixham frequently. I have very fond memories of the place.

14/06/2020 07:24:41 UTC
Womble said :-
Not on bikes yet as far as i know but modern cars seem to have this start stop system. I wonder how they far if you live on a busy rode where your straight out in the traffic. your 5 mile commute to the office could see the car starting 20 or so times and not giving the engine a opportunity to warm up. As for bikes depends which one I'm riding but my old British single once I see oil returning to the tank we're away.
14/06/2020 06:10:57 UTC
Ren - The Ed¹ said :-
Hi Womble. Ohhhhh yes, there's stop start on some of the scooters at least because the SH125 I test rode a while back had it. I'm sure there'll be a motorcycle or two with it too, if not now then soon.

How do you "see" oil returning to the tank? I presume it's a dry sump but does it have a clear tank or return pipe?
14/06/2020 06:34:33 UTC
Ren - The Ed¹ said :-
The old childhood holidays eh Bogger. For myself many of them were either Yorkshire or North Wales, West Burton and Criccieth. Sat on the wheel arch of a grey Fergie and straw on the trailer or on a stoney beach eating ice cream. By 'eck, times wur 'ard but we wur 'appy. It wasn't all black and white back then though, we had colour by the time I was born.

14/06/2020 06:39:27 UTC
Keith m. said :-
Bob. Yes. 80s Kawasaki’s . I had a couple of gpz’s. You started the thing up and it went straight to 4000rpm and no amount of adjustment would stop it. Used to ride off as quickly as possible to get the choke off.
Normally I push my bike down the alleyway and start up while I put my gloves on. Just keep the revs down for the first few miles.
14/06/2020 07:28:59 UTC
ROD said :-
Womble, I believe that the car stop/start system does not start working until the engine reaches its operating temperature.
14/06/2020 08:01:02 UTC
Upt'North said :-
Car Stop/Start systems are a PITA, thankfully cars have a switch to disable such nonsense. Apparently they're fitted to save the planet or cheat emissions.
14/06/2020 11:40:21 UTC
Borsuk said :-
Mrs Borsuk’s car has that system. Why do I think it is a cunning system by the manufacturers to sell more starter motors and batteries. On a 12 mile round trip journey that normally would require 2 starter operations the bloody thing is starting and stopping about 30 times each way.

My normal bike starting routine goes something like this.
Wheel bike out of drive onto road. Start engine, put on helmet, put on gloves. Take off gloves, take off helmet, fit ear plugs, put on helmet, put on gloves. Sit on bike, take off gloves, take ofF helmet, pull snood up to proper position, put on helmet, put on gloves. Prepare to move off, stop from moving off, take off gloves, secure bloody helmet, put on gloves. Stop engine as by now it is overheating. And people wonder why it takes me so long yo get ready.
15/06/2020 12:11:44 UTC
Ren - The Ed¹ said :-
HAHA! Oh yes, then set off get 2 miles down the road and remember you've forgotten the tool you are taking to your friend's house, the very reason for the journey. Then repeat the same routine. Gosh, and people worry about stop start systems :-)
15/06/2020 08:50:35 UTC
Womble said :-
Ren yes my old Matchless is dry sump (mostly) to check the oil is returning to the tank you just unscrew the cap and have a peek. Simple technology.
I've no experience of stop start but have seen a few cars with it. Like Borsuk said a good way to sell parts. not convinced it saves anything.
15/06/2020 07:54:37 UTC
Ren - The Ed¹ said :-
I suppose I could check my oil is flowing by removing the rocker cover... I need one of them perspex windows don't I.
16/06/2020 11:36:28 UTC
nab301 said :-
@ Womble Quote "As for bikes depends which one I'm riding but my old British single once I see oil returning to the tank we're away."
If it's like my Enfield (hypothetically of course) just because the return pump is scavenging oil that has wet sumped from the previous day doesn't mean that the feed pump is actually pumping oil to the crankshaft ....

@ Ren Quote "I suppose I could check my oil is flowing by removing the rocker cover..."
No need, Honda thoughtfully fitted a little bolt on the R/H rear of the cam/ rocker cover,(there are oil ways drilled in the cover linked via an internal O ring between cylinder head main oil feed and cover) loosen it with the engine running at your own risk to check oil flow , I did and spent a lot of time cleaning oil off my then new CB125F!
I'm not sure if you ran the engine without the cover if oil would just dribble out or hit the ceiling of your garage/ shed, maybe you can organise a video ? Photo of cover with oil ways and Mayo on my new at the time CB125F..

Posted Image
16/06/2020 08:50:59 UTC
Ren - The Ed¹ said :-
So nab301, you want me to run my aged CBF125 without the rocker cover to see if their is a geyser of oil or merely a dribble to the cylinder head. You just want me to ruin my bike doncha!

Yes of course, there's a 10mm socket to the rear of the rocker. That's handy. I wonder if it'd take an oil pressure gauge from there... #totallyunnecessarybutfun.
Posted Image
17/06/2020 07:42:59 UTC
Bob said :-
Ren, do you recall on your SLR650 the oil feed to the head was external?
There was a Banjo 12mm bolt connecting the oil feed line into the head.
Some SLR and FX owners (me included) used to crack that bolt a little when first starting the bike after an oil change to check for flow then nip it back up once reasured. The particular problem on that bike being the dry sump oil system and the possibility of air lock in the feed pump.
I wouldn't run the engine without the rocker cover - you'll find the flow rate is surprisingly high!
18/06/2020 02:09:32 UTC
Ren - The Ed¹ said :-
Yes I recall the external pipe. There's something quite reassuring about seeing a pipe feeding oil to the top of the motor. I know I KNOW there's nothing wrong with internal routing but I find external pipes satisfying. Maybe I'm going steampunk. Cheers for the heads up on the rocker cover ha!
19/06/2020 08:29:50 UTC

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