Oil cooler suggestions?

[Nessism]

Even though I've spent a lot of time and money fabricating oil cooler hardware, I tend to agree with Tkent; under normal conditions a GS engine does not need the cooler. Problem is, not everyone runs their bikes in a "normal" fashion. The cooler will be useful when the temperature is HOT outside - 90+ F. Overly hot oil will thin out more than desired thus you will get more engine wear than ideal. Engine wear like this is not going to be readily apparent - it will take extended usage for the wear to manifest itself in symptoms like loss of compression and burning oil.

Just about every air cooled road bike made since the mid 1980's had an oil cooler installed from the factory - including many GS bikes. None of these bikes have thermostats as far as I know. The key is to use a fairly small cooler where they can take the edge off the heat but not overcool the oil if you run around in cold weather all the time, or take lots of short trips. Check the size of the factory GS coolers used on the 550/750/1100, or the Honda Nighthawk sized coolers. Hard to go wrong copying the factory.

[Dan Ruddock]

If you look at the 8 valve and the 16 valve heads side by side there is a lot more space between the ports for airflow threw the 8 valve head for much better cooling. When Porsche was racing there 917 in the 70's reporters asked why they did not go to a 4 valve head like thier competitors did, there response was more room for cooling fins. A over heated head will overheat the oil. Yes VW and Porsche always put oil coolers on thier cars but the demands on cooling in a car is far greater than a motorcycle because of the added weight. Dan

[Jim Hansen]

Oil Temp.

I once read somewhere a claim that the Suzuki GS series and the BMW airheads tended to overheat their oil . So I installed an oil temp. gauge on my 1982 GS1100G with the sensor located at the oil pan drain plug.

My first discovery was that the oil usually runs overly COLD. Even when riding in moderate temperatures, ~70 degrees F., the gauge would not even move off the base 120 degree peg for at least 20 minutes. During my 32-mile ride to work, the oil temp. would very slowly move up to a max. of about 180 degrees after 30 minutes of riding at 45-70 mph. It seemed that there was no problem at all regarding excessive oil temp.

Then I took a ride up Hwy 5 in California, air temp. about 100 degrees, cruising at a steady 70 mph. As usual, the oil temp. slowly rose to 180 degrees after 20-30 minutes. Then I noticed that the oil temp. continued to slowly increase, to 200, then to 220 degrees F. I expected that the oil temp. would level off, but it continued its very slow increase. After riding for 2 hours it had slowly risen to 270 degrees, and was still rising!

From what I have read about oil, 270-degree oil should not cause an immediate engine "failure" (piston seizure, etc.), but I think that this high oil temp. could cause increased engine wear and is probably bad for the gaskets and seals. The oil viscosity gets pretty low (thin) at 270 degrees and the longevity of the oil is greatly reduced (I was using Castrol 20/50 weight, non-synthetic oil).

The oil temp. was still rising when I decided to stop at a rest stop and let the engine cool off for a little while, so I don't know how high the oil temp. would ultimately have gone. I think that an oil cooler is a good idea if you ride for sustained periods of time, at moderate-to-high speeds in warm weather.

[dirtyfingers]

A local bike guru tells me that an oil cooler may be hooked up at the oil filter cover. He showed me a 16 valve filter cover and cooler, and told me that one could be easily fashioned for an 8v motor. This seems the way to go, would make a nice clean install. I also learned that later 1000's and 1100's had ports for an oil cooler already there, just blocked off.

[srsupertrap]

Yes you can add a thermostatically controlled bypass valve between the engine and the cooler. below the set temp it bypasses the cooler taking the cooler out of circuit.
my old Kerker engine oil cooler was like that.

+1: Or find a used Lockhart BP-180 thermostat which as the name implies opens @ 180 degrees.

The oil temp. was still rising when I decided to stop at a rest stop and let the engine cool off for a little while, so I don't know how high the oil temp. would ultimately have gone. I think that an oil cooler is a good idea if you ride for sustained periods of time, at moderate-to-high speeds in warm weather.

I have got the same set up as does Renobruce which includes the VDO temp gage with a Lockart 700 oil cooler (larger of the two). I have noticied the highest oil temperatures actually occur when slogging through stop n go commuting traffic. When you stop to let your bike "cool off", turn on the key again and check the oil temperature. You will notice the temperature will actually increase or spike over the temperature when you were riding . . .

[renobruce]

A local bike guru tells me that an oil cooler may be hooked up at the oil filter cover. He showed me a 16 valve filter cover and cooler, and told me that one could be easily fashioned for an 8v motor. This seems the way to go, would make a nice clean install. I also learned that later 1000's and 1100's had ports for an oil cooler already there, just blocked off.

Not entirely true. You can't use the 16V cover on an 8 valve. The 8 valve cover is round and mounts with 3 bolts; the 16 valve cover has 5 bolts. The only way to hook up the lines to the filter cover on an 8 valve is to fabricate a pick-up tube that will take the oil from the supply port in the case behind the filter and make a port on the 8 valve cover. Then use the existing port (where the bolt is on the 8 valve cover) to return the oil. TomMLC did this on his GS1000.