Ideling an engine too long without use of fan

[mattcfish]

So, can anyone quantify what too hot is? If I put a temp gauge on the heads what is the max temp before damage occurs? I have an oil temp gauge in my pan (cooler than heads I'm sure). Sometimes during very hard riding it can get into the 265 F range.
Normal riding (for me) is around 190 to 205 F. Is oil pressure more important than temp?

[Airhead Wrangler]

Originally Posted by mattcfish

Is oil pressure more important than temp?

The two go hand in hand. As oil gets hotter, it loses viscosity. As it loses viscosity oil is able to flow more easily through tight spaces and puts less back pressure on your oil pump, resulting in a loss of oil pressure. It's ALLLLLLLLL related.

[mattcfish]

Originally Posted by Airhead Wrangler

The two go hand in hand. As oil gets hotter, it loses viscosity. As it loses viscosity oil is able to flow more easily through tight spaces and puts less back pressure on your oil pump, resulting in a loss of oil pressure. It's ALLLLLLLLL related.

Obviously, let me clarify, a good oil pump will produce more pressure than a warn out one when hot. 50 lbs of pressure at 300F has to be better than 10Lbs at 300F or 10Lbs at 180F for that matter....right?
At some point the oil is just too hot no matter what pressure it's at. I just want to know how hot that is?
Or is it that the expansion of some internal parts will become so great that no amount of lubrication will prevent seisure?

[motu]

I would expect an Airhead to be far better than a normal aircooled bike for extended idling. Those cyls sticking out there with vertical fins, hot air rises and all that stuff. On a normal bike with vertical engine and the a tank above the engine and horizontal fins there could be problems - but I've given normal bikes a hard time in that department with no problems. I'd be complaining to the manufacturer if my airhead overheated more than some cheap nasty bike.

[Airhead Wrangler]

Originally Posted by mattcfish

Obviously, let me clarify, a good oil pump will produce more pressure than a warn out one when hot. 50 lbs of pressure at 300F has to be better than 10Lbs at 300F or 10Lbs at 180F for that matter....right?
At some point the oil is just too hot no matter what pressure it's at. I just want to know how hot that is?
Or is it that the expansion of some internal parts will become so great that no amount of lubrication will prevent seisure?

Your most critical bearings, mains and big ends, depend on an oil film to prevent metal on metal contact. As your oil gets hotter and loses viscosity it loses it's ability to resist the pressure of a rod being forced into a crank journal by combustion pressure. At what exact temperature this occurs depends on your oil formulation and how much load the engine is under. I won't even venture a guess because I have no idea. No amount of oil pressure will prevent this if the oil is not viscous enough.

[disston]

It has been suggested to me that idling for extended periods of time is not good for the engine because the engine does not rid it self of excess heat that well if standing still. Excess heat is bad for engines in general. Maybe the Airhead engine can do this better than some other engine designs but it is still not recommended as a regular diet. I think it prudent to try and not idle the engine for extended periods of time.

About the only time I might want to have the engine idling for a longer period of time is when balancing the carbs. I am able to balance the carbs with out idling longer than a couple of minutes. If I need more time than this I take the bike out and ride some, then adjust some, then ride some.

I have been stuck in traffic a few times and the bike did seem to be over heated. I rode on the apron or the break down lane to the next exit. The bike was fine after words but it ran funny while it was over heated.

The advice about not over heating the engine is not original to me. I have heard this advice from people with much more experience than I have. I have always considered this good advice.

The box fan may be helpful to some riders sometimes. I don't have one.

[Big Bamboo]

One more thought; at idle, the oil pump is pushing the least amount of oil through the engine, with the oil at max temperature and it's lowest lubricity. Can't be a good thing...

[Prutser]

The only thing I noticed is that some airheads had problems with valve seats comming out of the heads when they got to hot.
A lot of those times the heads have been overhauled to use unleaded fuel.They just didn't do a good job.
It did happen even more when they were used for a sidecar.
On events in the netherlands where sidecars were used to take handicapped people for a ride out, and the bikes were driving slow for a long time it was a common airhead failure.

My solo bike's have had hours of idling on muddy forest tracks,trying to get through in serious heat.

Had no heat problems with more than 400.000km....

Just my experience.

[Airhead Wrangler]

Who just completed a massive rebuild on their bike because their idiot brother in law used it recharge a battery on a ride-on mower or something stupid like that and left it idling for an hour? I can't remember whos bike it was, but I remember there being a LOT of damage.

[Prutser]

Originally Posted by Airhead Wrangler

Who just completed a massive rebuild on their bike because their idiot brother in law used it recharge a battery on a ride-on mower or something stupid like that and left it idling for an hour? I can't remember whos bike it was, but I remember there being a LOT of damage.

That is out here somewhere. I have seen some damage out there too.

Once a guy came up to me that had a R1200C that stopped idling after 5 min.(so he said)
But when he brought the bike all the paint was falling from the engine, inlet rubbers had melted the oil in the engine was burned. After I checked the bike the wires from the hall sensor were melted, that was the first thing that stopped the engine.........

At least we don't have much paint that will fall off

[Airhead Wrangler]

Originally Posted by Prutser

That is out here somewhere. I have seen some damage out there too.

Once a guy came up to me that had a R1200C that stopped idling after 5 min.(so he said)
But when he brought the bike all the paint was falling from the engine, inlet rubbers had melted the oil in the engine was burned. After I checked the bike the wires from the hall sensor were melted, that was the first thing that stopped the engine.........

At least we don't have much paint that will fall off

He got lucky. I've heard several stories of oilheads catching on fire from idling too long.

Here's the overheated GS thread:
http://advrider.com/forums/showthread.php?t=645324

[DaveBall]

I think the problem is that a lot of people do not know how long is too long. We have to get real here. There are a lot of things to consider before saying that an airhead cannot sit at idle for a few minutes. And we have to use some common sense. Sure, sitting at idle is going to allow the engine to build up heat. That is expected. Does that mean that we have to turn the engine off at every stop light? No. These engines were designed to be ridden in normal every day traffic. That includes sitting at idle for short periods of time.

Yes, the reason for the engine failure is due to overheating and the oil not being able to lubricate properly. So to help eleviate that problem, make sure you do proper maintenance. Change that oil and filter on a regular basis. And use a top quality oil that is rated for the application. If you have to commute thru heavy traffic with stop and go situations, change the oil more often. Maybe install an oil cooler. Or if all that will not work for you, commute on a different bike.

There are lots of us who have gotten well over 200,000 miles out of our engines without major rebuilds or breakdowns. And we ride the bikes as they were originally intended. Don't over load them and do proper maintenance. And learn to use the upper end of the tachometer. Get those revs up and let the oil circulate.

[cycleman2]

Having owned both oilheads and airheads the manufacture advises to not let them idle for more than 10 minutes. That sounds like a good idea to me.

I always use a fan if I'm adjusting carbs, sync etc as 10 minutes can go by fast if you are preoccupied. If I'm stopped in a long line of traffic, like a railroad crossing, where you know you are going to be there for awhile I will shut the engine off, same as if I'm at a border crossing with long lines of traffic. Traffic lights and other similar type situations I let the engine idle.

Now if you want to talk heat the oil temp on my Softail has hit 270 F, 2 up in the mountains, lots of stop & go construction, 90 +F air temp. I run synthetic oil but that's too hot in my mind so I put an oil cooler on the engine shortly after that.

A certain amount of common sense has to be used when idling an air cooled motorcycle.

[jackd]

Originally Posted by Airhead Wrangler

Who just completed a massive rebuild on their bike because their idiot brother in law used it recharge a battery on a ride-on mower or something stupid like that and left it idling for an hour? I can't remember whos bike it was, but I remember there being a LOT of damage.

That would be 'Jimbee' up here in Vancouver. He had quite the mess on his hands. The saddest part was that he went to the trouble of re-buiding the engine, with much encouragement from the forum members. Eventually he was having problems with the cylinder hold down studs pulling out of the block which led to further repairs. I was wondering if somehow the block had lost its strength where the studs thread in. I'm hoping that it came to a satisfactory resolution at the end.

[crazydrummerdude]

Originally Posted by limeymike

I too have found it almost amusing that airhead riders don't think they can idle these engines for more than a few minutes without assistance from fans.

...

These things are not fragile, they can handle idling just fine.

Try idling up a mountain waiting in line to enter Yosemite during construction of the main road, on a beautiful weekend.

I'd say that was excessive idling, and definitely the hottest my bike has ever run.