Do's and Dont's of Air-Cooled

mjunk1 · #1 06-26-2008, 07:42 AM

I read a post the other day that said most people don't know how to treat/work on an air cooled engine.&nbsp\\; It occurred to me that I really don't know if there are any special rules or guidelines.&nbsp\\; Last night while riding in 90 deg temps it made me wonder if there are special considerations for traffic jams.&nbsp\\; Do you ride it until your knees start to bake and then stop and let it cool down?&nbsp\\; So, for those of you with a wealth of experience, what are the do's and dont's of the air-cooled Evo?

js124 · #2 06-26-2008, 08:06 AM

If your engine gets hot enough to make your oil pressure drop to 0 you need to stop and let it cool .

t150vej · #3 06-26-2008, 08:37 AM

Well, lots of people these days don't actually ride anyway - trailer to a rally and cook down the top end by styling and profiling and going nowhere. I guess that's why they trailer everywhere. but...
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Low speed jet and idle screw setting have a lot to do with it and of course the ambient temperature and and length of delay are major factors. When you feel it&nbsp\\;idleing rough, spark knocking on gentle take off and your oil pressure is low enough to make the light flicker at idle, then it's time to either get some open road or get parked asap and give it at least 15 minutes to cool (or longer) if you have to be in the same traffic jam. Some states (cannot rememeber which ones) recognize the danger to air-cooled engines and will actually legally allow a motorcycle or air-cooled cars to run the shoulder in a traffic jam. Of course that's a dangerous thing because of road debris and vengefull car drivers running you into the guard rail.
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Also, remember the oil is not circulating as rapidly at low speed, therefore not helping to cool the bearings etc. Running high speed it circulates quickly and oil temps may read 190 and when you drop off into a town with moderate hold-ups for lights etc., your oil temp will actually fall because it's sitting in the tank longer&nbsp\\;and cooling there.
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Yep, mostly a feel thing, knowing your machine and responding to what it's behavior is telling you........

mjunk1 · #4 06-26-2008, 12:58 PM

So the signals of issues are the oil pressure dropping and the engine struggling to get out of idle?&nbsp\\; I don't have an oil temp guage, but the oil pressure guage seems pretty accurate. Ususally it has stayed above 10psi even at idle.&nbsp\\; The engine makes more noise than I am used to anyway, so it is a little hard to tell - right now - what is a problem and what is just the sweet melody of the engine!

mp · #5 06-26-2008, 01:55 PM

An Evo takes a lot longer to get hot than a Twin Cam.&nbsp\\; Just don't sit in traffic jams with the engine idling.&nbsp\\; Turn it off if you have to, or turn off and find another route.

Dr.Hess · #6 06-26-2008, 02:15 PM

Sitting idling a long time will raise the head temps.&nbsp\\; I've observed this on the fuel injected Sportster while I was tuning the fuel maps and data logging.&nbsp\\; If you're working on it in the garage, a box fan blowing on the motor will drop the temp down to normal riding temps.
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Oil coolers are one of those "I Believe" things.&nbsp\\; I have one on both bikes.

dog155 · #7 06-27-2008, 02:56 PM

Can say this for sure Shovelheads will not tolerate long idle periods in high heat.Stands to reason Evo's and TwinCams would not be far behind.If they get to hot and white smoke starts puffing out the exhaust,you have&nbsp\\;idled too long,the next thing is sieze up.

t150vej · #8 06-27-2008, 03:37 PM

I agree, Dog.
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Basically the same engine except the Evos are aluminum cylinders and the jugs and heads all bolt with the same stud. Evo jugs&nbsp\\;will cool quicker than a Shovel/Pan/Knuckle, but&nbsp\\;they all&nbsp\\;suffer the same damage when overheated.

mjunk1 · #9 06-27-2008, 10:17 PM

That's what I was basically worried about.&nbsp\\; You know your screwed if you get too hot and it always means lots of money.&nbsp\\; I suppose it doesn't happen immediately or anything, so the tips and signs posted before are helpful for those times this summer I might find myself in a construction zone or something.

quigley · #10 06-28-2008, 01:51 AM

Get a oil cooler and then get this...

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