GS750E Overheat?

[82Suzie]

I just got my 82 GS750E back from the shop a few days ago, they performed a valve job, clutch adjustment and carb sync.
It's been sitting in the garage since then, but today I took it out for a short trip and rode it at around 75mph for a total of 7 miles.
I've always watched the temp gauge since the bike has been back on the road and it never got past 215 degrees. Around mile 7 I noticed both turn signal indicator lights on at the same time, no blinking, just solid on. I looked at the temp gauge and the needle was at the 320 degrees level. I slowed down and continued to ride it home a couple of miles. The temp lowered and the turn signal indicators turned off.

Any idea of what happened?
Could the temp actually have got the high?



Rick

[posplayr]

If you have an electrcial problem it could have affected your indicated sensor reading. Have you gone through your charging system? Quick test ring a bell? I wouldn't assume you actually ran that hot unless you can confirm the electrical is in good shape. Given the blinkers I would suggest that is not the case.

[Rob S.]

What was the outside temp?

[82Suzie]

Only 72 outside.
There was no change in how the engine ran, I don't think I would have noticed anything if I hadn't a temp gauge.
The temp gauge has always been slow to rise, I had just assumed the engine took a while to warm up, this seemed sudden.

[Rob S.]

...The temp gauge has always been slow to rise, I had just assumed the engine took a while to warm up, this seemed sudden.

My oil temp gauge has always been slow to rise, even before I installed a cooler. I have to ride it quite a few miles before the needle moves at all.

[dorkburger]

If I recall from your build thread, didn't you have some bad wiring/connectors?

[82Suzie]

After having been out of town for a couple of weeks I got back into this project. I checked the wiring harness and didn't find any issues. I pulled the chrome cover over the oil temp sensor and added insulation. Yesterday I took the Suzie out for a 100 mile ride. The weather temp was perfect at 79-84 degrees, blue skies and a small breeze. I rode four about 20 miles or so, first thru the city and 40 mph and then on to the freeway 65-75 mph. The oil temp gauge showed a slow increase in temperature but at some point it hit 320 again. I decided to keep riding as I didn't notice a difference in how the engine operated. After 60 miles I stopped for gas and after starting the engine, the temp gauge registered somewhere around 260. So I began to distrust it. I took the freeway back at a steady 70mph, the gauge displayed 320 the entire way back.

Could the sensor need to be replaced or is that normal operating temperature?


Rick

[dorkburger]

The only time my old 1100e ever hit 320 was in ridiculous traffic in ridiculous heat. its been a long time, but I seem to recall that it ran on the lower end to maybe the middle of the scale.

[posplayr]

Could the sensor need to be replaced or is that normal operating temperature?


Rick

If it is correct, 320 degF is way too high. @210-220 is much more comfortable with 270-280 degF max in the summer. This is especially true for a small displacement 16V like at 750. With a Series R/R and small oil cooler a 1166 high compression engine stays within these ranges and the size and cooling areas are nearly equivalent.

You are either suffering from an electrical problem or low oil pressure causing heating problems. My 1981 GS750EX did not have a temperature gauge but it did have an idiot light and as best I could tell it ran very cool no matter how bad I flogged it.

Do you have a factory manual? It tells how to test yoru meter and sensor. And a handlebar volt meter will give you an indication about your electrical system.

Failing doing any of that you could probably find a psychiatrist for the bike. Maybe he would have a volt meter.

[82Suzie]

I tested the oil temp gauge and it checked out AOK. I went and tightened it down to the sensor real tight.
I'm hoping it was just too loose. I'll ride her again Tuesday.

[82Suzie]

Ran it at 70-75 mph for 10 miles and the temp gauge hit 320 again.
I talked it over with a MC mechanic I know well and I suspect a defective OT sensor.
I bought a used one and will install it over the weekend, and test ride again.

[82Suzie]

Issue resolved.
I studied the wiring diagram and went over everything and found a wiring coupling located in the headlight shell that while it appeared fastened, really wasn't.
Pressed both sides until I heard a click and the problem was solved.
Took Suzie out for attest ride and enjoyed myself. Temp gauge slowly rose to 210 and stayed there.

[andy10889]

Glad you got it fixed. The small stuff always takes the longest to get sorted.

[T8erbug]

Nothing like reading a resolution. Almost makes me feel like I accomplished something of my own Glad you got it figured out