How do I *KNOW* if I'm overheating

[away_man]

1982 GS1100EZ

These bikes have a factory oil temp gauge. When I start the bike and let it warm for a bit, the temp gauge stays at the bottom. If I ride it for a bit, it slowly moves up. If I stop, it quits going up. Seems normal.

The problem is, if I ride for any real length of time (20 minutes?), the guage continues to go up, and stops a bit shy of the 320 mark at the top, regardless of city/highway/stop lights/etc. If I stop for a while (5 minutes), the indicator starts moving back down, as if it is reading the correct, WAY too hot, temp.

Rgierer has suggested that the guages and electronics on these old bikes tend to be notoriously faulty/inconsistent, and my oil temp guage is lying to me. I would love to believe that, but it just seems to be too consistent to be wrong.

I went for about an hour ride, so the temp was definitely up there (outside temp was around 55-60), then drained the oil to check the temp with a meat thermometer. Stuck it in the oil stream as it drained, and it immediately pegged. Unfortunately, it only goes to 190, so I don't know how hot the oil actually was (I may need to get a candy thermometer). I can say that the oil was about the consistency of water, and felt very hot through my unlined leather gloves.

Saw another post about the "sizzle test" - toss a little water on the hot engine and see if is vapors away (normal) or beads and pops off (very hot). I forgot to do this, because I was trying to get to my oil before it cooled, but is this any indication of actual oil/engine temp?

One other note- the bike runs just fine at any speed when the gauge is reading close to 320; other posts have indicated that the engine would/should be missing if it was really that hot.

Thoughts? Troubleshooting tips? I'm afraid that my two weeks of having a functional bike after the last problem is going to get cut short by needing to pull the oil pump. (I'm assuming a faulty oil pump is the only reason an air-cooled bike would overheat, although I guess it could be a clogged oil passageway somewhere?)

Thanks in advance for any help on this one...

[mark]

Seems to me if your oil pump wasn't working you would have toasted or frozen up your motor long ago.

The way to fry these motors is to let them idle without any air moving over them. Oil temp should go DOWN when your riding it normally, and UP if you just let it idle for a long time. Don't let it idle much longer than about 5 minutes without a fan on it.

Sounds to me too, like something is wrong with your gauge.

If you really overheat it badly, it will start pumping white smoke (oil).

[BadBillyB]

Poor oil circulation could cause the temps to be higher than normal in certain areas of the motor........Read this thread..BadBillyB...http://www.thegsresources.com/_forum...ighlight=gauge

[DaveDanger]

I think it's important to determine if your gauge and sending unit is accurate or not. I did a little research on the net and found no specific motorcycle temperature references but found lots of references to "This oil is good to 300 degrees" with a kind of normal range of 200 to 280 being standard. Every mention of a temperature higher than 300 was referenced to "viscosity breakdown".
I'm not sure on your model exactly where the oil temp sending unit is located, nor how difficult to remove, but I would do that, and connect it back up to the gauge wiring, and if possible, at least test it in boiling water (212 degrees) and see if it's accurate at that temp. Drop the sending unit in a small sauce pan and boil it with a propane torch or a hotplate.

[away_man]

Thanks for the help, guys! I am feeling better about the idea that the engine/oil isn't really running as hot as the gauge is indicating, but I'm just not going to feel comfortable about it until I know for sure.

After looking at the post Billy referenced, I'm thinking I'll pull my oil pan and have a look around. This bike was very well cared for by the PO, but with only about 20K on the clock, there's probably a good chance that strainer hasn't been looked at since it left the factory.

Dave, thanks for the gauge testing idea; it's such a simple test that I should have thought of it myself. Now if I can just figure out where the sending unit for the temp guage is....