Riding away with a cold engine

[v65]

If the FJR was your livelyhood (which I doubt), what's a couple of minutes and some gas going to cost to let it warm up gradually?

Well, as Kevin Cameron explained it several years ago in Cycle World you are actually doing more harm than good. The excess fuel that is not burnt off in a cold engine is actually corrosive to the cylinders. I would guess that this corrosive effect is not really doing any real damage, but his point was that warming an engine was more damaging than not.

 

[E1Allen]

I make sure I have everything on and the music blaring before I start my engine. Then I take it out of the driveway and immediately do a 10-20 second burnout to make sure the tire is warm and the bike is hot.

 

[Knifemaker]

..Well, as Kevin Cameron explained it several years ago in Cycle World you are actually doing more harm than good. The excess fuel that is not burnt off in a cold engine is actually corrosive to the cylinders. I would guess that this corrosive effect is not really doing any real damage, but his point was that warming an engine was more damaging than not.

Ok, someone needs to explain this to me. If the engine is cold..and is not burning all the fuel..does it make any diffrence if the bike is in gear and movimg or if it is in neutral and sitting in the driveway?

Seems to me that in either circumstance there will be unburned fuel and for that matter, if you crack throttle to increase the amount of fuel even more (as in riding away), you would also have a higher percentage of unburnt fuel.

Splain...

KM

 

[SkooterG]

Ok, someone needs to explain this to me. If the engine is cold..and is not burning all the fuel..does it make any diffrence if the bike is in gear and movimg or if it is in neutral and sitting in the driveway?Seems to me that in either circumstance there will be unburned fuel and for that matter, if you crack throttle to increase the amount of fuel even more (as in riding away), you would also have a higher percentage of unburnt fuel.

More fuel (from riding) = more heat. More heat = quicker warm-up time. Quicker warm-up time is good, no?

 

[Bustanut joker]

One bar warm up is all I ever do most of the time. Sometimes not even that.

You're tougher than me :huh: When it's as cold as it is here I tend to hit five or six bars to warm up! :lol: Or, about one every three miles

:jester:

 

[FJRMGM]

I'm with the majority - start engine and put on helmet and gloves and off I go but not hard for a couple of miles.

On my SV-650, which has a digital temp gauge, it takes almost five miles of riding at 55-60 mph in 70 degree weather for it to get up to 185 degrees water temp.

 

[Knifemaker]

...More fuel (from riding) = more heat. More heat = quicker warm-up time. Quicker warm-up time is good, no?

Yes, good. but what you are saying is that the bike will warm up so much faster that it will offset the bigger increases in unburnt fuel ...... (which are appearently contaminating our oil and damaging our engines.)

And if the tolerances are so tight on modern engines, how much unburned fuel is really getting into our oil?

Sorry, I'm from Missouri, you have to "show me" some data or test results here. If I double the amount of unburned fuel..that seems to be getting past the rings and infecting the oil , I would of course have to decrease the time it takes to "warm up" by more than 1/2 to make it worthwile.

I'm still thinking that letting the engine run at low speeds with cold oil is better than letting it run at higher speeds with cold oil.

The only reason I let my car warm up in the driveway (for 2-4 minutes, not 10) is so when I turn on the heater it actualy blows warm air at me. I only do this on days it is below 32F.

Some folks I do think tend to go overboard with this, but I really do not think I am doing any real damage letting my car or bike warm up abit before I take off on cold days....

KM

 

[huron52]

When ever possible I like to wait a few minutes to allow the bike to warm up.

It doesn't take long.

Wheel the bike out of the garage.

Start it up,

walk around the bike, (it's called a circle check)

checking brake lights, head lights, turn indicators, running lights, horn

Go back and close the garage door,

lock the front door,

do up jacket,

put in ear plugs,

put helmet on,

put on glasses,

put on gloves,

and bingo you have the bike warmed up at two bars (gen 1)

Ok.... maybe you have to get on the bike flip up the kick stand and then wait 30 seconds.

 

[wheatonFJR]

When ever possible I like to wait a few minutes to allow the bike to warm up.
It doesn't take long.

Wheel the bike out of the garage.

Start it up,

walk around the bike, (it's called a circle check)

checking brake lights, head lights, turn indicators, running lights, horn

Go back and close the garage door,

lock the front door,

do up jacket,

put in ear plugs,

put helmet on,

put on glasses,

put on gloves,

and bingo you have the bike warmed up at two bars (gen 1)

Ok.... maybe you have to get on the bike flip up the kick stand and then wait 30 seconds.

+1 on this procedure

 

[jestal]

Jestal:
I pretty much agree with you on the bike, but what about those of us who ride the bike in ambient temps that aren't the norm for most riders? The coldest temps I have started and ridden my 07 FJR is 17 degrees, F. Cranked over four or five times before it fired. By the time I got my helmet and gloves on, bike had idled perhaps for two minutes, with no indication on the temp gage. Hopped on it and rode off at a leisurely pace for a couple of miles.

I've been up at "Frostbite Falls" MN many a time when the major car and battery manufacturer's were doing cold weather testing on their products with the temps in the -35 to 40 below range. Just about all of them stayed at the Holiday Inn. Didn't recall any of them starting up their vehicles at the motel at those temps and driving away within 30 secs. They couldn't keep the windows from frosting up and couldn't see to drive. Saw a few plastic steering wheels and seat covers crack at those temps.

With today's modern engines and tight clearances, at temps of -35 to 40 below, how long would you say it takes the oil to reach the camshaft galleries? I would think it would be prudent to allow the engine to idle at least a minute or so to assure oil is circulating completely through the engine before driving off in those kinds of temps.

If you watched battery testing then all those guys care about is that the battery cranks the engine over. Our testing goes WAY beyond that. We want to make sure the engine will not damage itself if cold started and driven and we REALLY want to make sure the fuel injection (or carbs back-in-th-day.....LOL) were calibrated such that there were no driveablity issues when started cold and driven. An auto company really does NOT want a package that will sag and stall and cough and puke if the customer cold starts and pulls out onto the main highway immediately out of their driveway. Damn the engine when a logging truck is coming at you at 70 and you pull out in front of it.....been there and done that in Kap many times.......you just want the thing to respond and GO. We do extensive cold testing all winter at Kapuskasing, Ontario for just this reason. In the process the engines themselves get brutalized by cold starts and immediate driveaways to make SURE the fuel injection system is calibrated correctly for cold weather operation. We typically put windshield covers on and even run electric heates inside the cabin to keep the windows clear for immediate driveaways and/or we always wear snowmobile suits and put the windows down to prevent fogging when first driving off. Seriously. Plus, we always follow a regimented driveaway schdule that involves a LOT of heavy throttle accels with the engine cold to make sure the calibration is good. We will do an extended idle warmup on occasion to make sure the system is capable of that, too, but the drive-aways are much more important to get rigght for safety. Sounds like you observed a bunch of wussies doing cold weather starts....LOL.

It only takes moments for the oil to reach critical areas. One big misconception about engines is that they are "running dry" until oil pressure reaches the critical parts. In fact, the bearings hold considerable residual oil and a hydrodynamic bearing (such as rod bearings, main bearings, cam bearings, etc....) makes it own oil pressure due to the hydromanic action of the journal rotating in the bearing. As long as some oil is there the bearing is fine for quite awhile even with no oil pressure or oil delivery. When the egnine is cold soaked the residual oil is very viscous just like the oil in the sump so it stays in the bearing for a long time and keeps the hydrodynamic bearing film thickness at acceptable levels. I have seen engines cold started with no oil pressure (done deliberately by disconnecting the oil pump or draining the sump) to measure how long it take before lifters start to clatter and bearings start to thump. The engine can run for for 60 or 90 seconds easily on the residual oil in the bearings. Engine "oil pressure" just delivers the oil to the bearings, it doesn't make the bearing work so as long as oil gets delivered in a reasonable amount of time the engine is fine. When hot, the (much) thinner oil does evacuate from the bearings much quicker so ready oil pressure is much more important but on cold starts the bearing retains so much residual (thicker) oil that it is protected for quite awhile.

 

[jestal]

Ok, someone needs to explain this to me. If the engine is cold..and is not burning all the fuel..does it make any diffrence if the bike is in gear and movimg or if it is in neutral and sitting in the driveway?Seems to me that in either circumstance there will be unburned fuel and for that matter, if you crack throttle to increase the amount of fuel even more (as in riding away), you would also have a higher percentage of unburnt fuel.

More fuel (from riding) = more heat. More heat = quicker warm-up time. Quicker warm-up time is good, no?

To answer this thoroughly you have to understand that fuel will only ignite and burn if the fuel atomizes and creates a burnable mixture. If you look at the distilllation curve of gasoline you can see that less and less percentage of it will atomize (or evaporate) the colder the fuel gets. So....the fuel injection system must put in a greater quantity of fuel to get enough to atomize to support combustion when the engine is cold. The engine is actually running at similar air/fuel ratios as when it is hot IF you only consider the amount of fuel that is atomizing. But, in very cold ambients, it is often necessary to put in 4 or 5 times the normal amount of liquid fuel just to get enough to vaporize to support the combustion for starting. Even with fuel injection, the fuel is sprayed into the port but most of it will condense to liquid and only a fraction of it will vaporize. Fuel can only burn it if is vaporized. Period. The rest of the liguid fuel just goes thru the combustion chamber and gets past the rings and/or blown out the exhaust and wasted.

This phenomenon is true of carbureted, throttle body injected, port fuel injection, etc. They all need about the same amount of "extra" fuel by volume to cold start and all of them put about the same amount of raw fuel into the crankcase and out the exhaust. I have personally run many tests comparing the cold start air/fuel ratios for different systems and they are very close to being the same.

Having laid this basis for the discussion there are two ways to obtain vaporization of the fuel. Heat and mechanical motion or turbulence in the port. Much more of the fuel will atomize at higher temps so less and less "extra" fuel is required as the engine warms up. When hot, virtually all of the fuel vaporizes or atomizes for combustion. When very cold (using -40 as the extreme) only about 5 % of the fuel vaporizes initially at startup due to the cold temp. If you could somehow mechanically mix the fuel by turbulence in the port more of the fuel will vaporize when cold and support combustion. There is very little mechanical mixing or turbulence at idle due to the low air flow thru the ports. Adding just a little load...i.e...upping the air flow by opening the throttle....gets a fair amount of mechanical mixing of the fuel/air going on thus increasing the amount of fuel that atomizes and decreasing the amount of "extra" fuel required. If you want "data" on this take your carbed hot rod out in the cold with a cold engine and the choke wired open and stab the throttle. Likely it will balk and gag on the transition but, once the engine RPM does start to come up, it will run fine and pull like crazy. There is no more fuel being added and the temp is not changing in the manifold or port that much in that short time but the extra air flow effects mechanical mixing that causes the atomization meeded even at those cold temps.

Point being, that, if you start and idle the engine will require much more "extra" fuel due to the poor atomization when cold and at idle with not much mechanical turbulence due to low air flow. It will run richer for longer to sustain idle. If you open the throttle and establish some air flow the "extra" liguid fuel requirement is actually reduced due to the large gain in turbulence to mechanically aid in fuel atomization.

If you look at fuel economy over the entire operating cycle then you are getting infinitely poor economy any time you are at idle as the engine is using fuel and not moving the vehicle at all. Start it and ride gently and you are at least getting some distance out of the fuel being added and actually reducing the amount of "extra" fuel being put into the cold engine. Minor effect if the ride is long but significant in winter short trips. Fuel injection systems are much more accurate at delivering the correct (and minimal) amount of fuel required for any ambient start and operation so the driveablility will always be fine. Not like a carb system that often required some warmup to prevent poor driveability when cold.

Start it and ride it. Best use of the fuel you are burning. Least amount of "extra" fuel required due to added mechanical mixture motion for best atomization and quickest warmup.

 

[FJRSTAR]

One bar warm up is all I ever do most of the time. Sometimes not even that.

You're tougher than me :huh: When it's as cold as it is here I tend to hit five or six bars to warm up! :lol: Or, about one every three miles

:jester:

You Joker...you funny.

 

[markjenn]

Start it and ride it. Best use of the fuel you are burning. Least amount of "extra" fuel required due to added mechanical mixture motion for best atomization and quickest warmup.

Great writeup (as always). The overall rule of thumb is that you should only warm up your engine at idle long enough so that it will smoothly take load and allow you to drive away. Certainly if you're starting an engine at 20-below, this requirement probably means a minute or three of warmup, but honestly, how many of us ever ride even below freezing? I'd venture to guess that less than 0.5% of all MC rides start out in freezing temps or lower. In the fairly moderate temps most of us ride in and with the mult-vis oil we all use, there is almost never any necessity for any warmup idle time whatsoever.

Any extra idling while you do whatever (coffee, walkaround, gloves, earplugs, helmet, jacket, electric gear plug-ins, etc.) is just wasting gas and is NOT doing your engine any good, although if you keep it under a minute or two, it probably isn't doing much harm either.

Unnecessary warmup idling is worse on an air-cooled vs. a water-cooled bike as they aren't able to circulate the initial heat as effectively so the top-end gets overheated very quickly while the rest of the motor remains cold adding extra thermal stress. This is the reason BMW includes this prominent warning in their R-bike OM:

"WARNING: Your engine should not be allowed to warm up with motorcycle standing still - risk of overheating! Ride away IMMEDIATELY after starting the engine. To avoid overheating the air-cooled engine and possible damage as a result, avoid even short warm-up periods at a standstill."

There have been documented cases of people starting their BMW R-bikes on fast-idle and going in the house for fifteen minutes to return to find their bike on fire.

- Mark

 

[Zorlac]

WOW,

I'm not a one percenter, I'm a half a percenter. :blink:

Thanks for you insight Jestal.

I just wonder why it never dawned on me to start it in first to avoid the high idle clunk.

 

[dhalen32]

How about this for you non-believers in driving off right away? In addition to the engine warming up while riding gently during the first few minutes after a cold start you are also more gently warming wheel bearings, final drive, etc. If the engine/transmission are the only components that are nice and warm but not all of the other moving parts then you might be causing some premature wear in these other cold systems.

Dave

 

[colin]

If the FJR was your livelyhood (which I doubt), what's a couple of minutes and some gas going to cost to let it warm up gradually?

Well, as Kevin Cameron explained it several years ago in Cycle World you are actually doing more harm than good. The excess fuel that is not burnt off in a cold engine is actually corrosive to the cylinders. I would guess that this corrosive effect is not really doing any real damage, but his point was that warming an engine was more damaging than not.

don't suppose you have a link to that? I guess I just don't get it.... Though I've not really looked around too much on it.... ?

cheers,

-colin

 

[CDN_FJR]

I'm going to run against the grain on this one. I let my bike get fairly close to normal temperature before I run anywhere near the normal load and shift points. I guess it's my background in aviation and engineering that gives me a guilty conscience from doing so.
That being said, the aircraft I fly now has very specific limitations for temperature applications, especially when cold soaked.

If the FJR was your livelyhood (which I doubt), what's a couple of minutes and some gas going to cost to let it warm up gradually?

I understand what you mean... I think this comes from flying air cooled planes like Cessnas... I think the main reason for a full warm up (and run up) is to ensure you have full power available for the take off run. You don't want a cold carburated engine sputtering and coughing down the runway (for obvious reasons). Saying that, I ride about 30sec after starting my bike... I just don't load it until it gets warm.

Richard

 

[FJRMGM]

This is the reason BMW includes this prominent warning in their R-bike OM:

"WARNING: Your engine should not be allowed to warm up with motorcycle standing still - risk of overheating! Ride away IMMEDIATELY after starting the engine. To avoid overheating the air-cooled engine and possible damage as a result, avoid even short warm-up periods at a standstill."

There have been documented cases of people starting their BMW R-bikes on fast-idle and going in the house for fifteen minutes to return to find their bike on fire.

Friend at work rides a 2000 air-head BMW and he gets on the bike, cranks the motor over with it in gear and that bike literally does not turn over two rpms before he lets out the clutch and takes off!!

He heard about the above and rides off IMMEDIATELY after starting.

 

[Checkswrecks]

Don't know about Beemers, but do know airplane engines well and the reasons are different for those. They are air-cooled and designed to have specific tolerances for cruise that don't exist when cold. They need to warm for the tolerances to be where they should be for operation. Probably the best example is the threaded area between the steel sleeve of the piston barrel and the aluminum cylinder head. Another is that the valve push-rods take a lot longer to warm than the cylinders do, so the rocker gaps can get to be extremely large (impact loads on the cam lobes, rockers, and valve stems. A lot of airplane engines also sit for long periods between use and the oil film can break, especially along the tops of the cylinders. In the absolute extremes of Alaska and northern Canada, it can get cold enough for the metal to actually become brittle and those guys break valve springs. (Yet another reason I don't want to live there!)

I remember the Cameron article and it's not actually the fuel itself that causes the corrosion, it's that the mixture is rich and dirty at cold idle. This leads to higher production rates for by-products that will mix with humidity. Mixing the hydrogen and sulfur from the rich exhaust gas with H20 results in increased acid (H2SO4) that the oil picks up. This has more to do with how often you change oil and how long you let your oil warm to evaporate/burn off some of the contaminates - but little to do with riding away on a cold engine.

Bob

 

[charismaticmegafauna]

<snip>"WARNING: Your engine should not be allowed to warm up with motorcycle standing still - risk of overheating! ....To avoid overheating the air-cooled engine and possible damage ....."There have been documented cases of people starting their BMW R-bikes on fast-idle and going in the house for fifteen minutes to return to find their bike on fire.

Sheesh..., add to that: rear-ends failing and turns signals that need two hands to operate --

talk about your 'endearing little quirks'....!!