Oil cooler (mounting of)

Aus das GS 500 Wiki: www.GS-500.info

Author: Goose, Translation: Herby

Here I explain how to mount an oil cooler to the GS.
Egli Tom is the one who mounted it and drives it this way in his racing series.

Some friends and I are working on a slightly different version that works according to the same principle. Measures and complete conversion kits are respectively available not earlier than after the publication of this complete customisation instruction. So, please refrain from asking questions like: "When are you finished?”
Basically, what is built in here is an oil cooler that cools the main stream of the GS, so the whole oil is pumped through the cooler, not only a part.

The following parts were used.

• 1 x Oil cooler
• 1 x Fastening-plate for oil filter cartridge
• 1 x Oil filter
• 1 x Hose kit
• 1 x original oil filter box plate
• 1 x Kit of compression couplings for the hoses
• 1 x Tube for feeding the oil back into the main oil duct.
• Several o-Rings

To understand what the oil circuit of the GS looks like in the oil filter box, have a look at the following picture.

The oil filter box is fed through the upper opening by the pressure generated by the oil pump. In the middle of the opening usually sits the oil filter. This is the runback duct into the main oil sump of the engine. As a result the principle of the oil flow is as follows:
Picture the engine as being closed and sealed by a cap. Thus the oil is pumped into the box, the only way out being the filter cartridge that covers the opening in the middle, and so the oil flows back into the engine after the filtering through this opening and lubricates it.

It is here, where the oil flow is tapped.

We’ll have a closer look at the cap of the oil filter box.

We drill two holes into the cap, one of them exactly in the middle. The positions of the holes in the cap are given, so it’s really simple. The holes are then to be milled to finished size to obtain a sealing surface for a bolt flange.

The middle one is the runback duct for the oil, and the lower one is the drain outlet out of the box into the oil cooler.

Behind the middle bolt flange is hidden a tube that leads right to the opening in the middle, and is of course sealed with rubber rings.
The whole looks something like this.

Now that the base plate is ready, we turn to the oil cleaning.

As consequently oil filter cartridges now can’t be used anymore, we need an external mounting plate to install a car oil filter cartridge for cleaning the oil.

This mounting plate could look like this, for example.

It works like the oil filter of the GS, with the only difference that it was inserted in sheet metal.

What’s still missing is the oil cooler. I won’t go into details here as concerns dimensions, the number of ribs and the size of the oil cooler, as these parameters greatly depend on the specific case.

Here for example Suzuki’s solution for the oil cooler of the F series.

A thermostat casing would be of advantage that first allows oilflow through the cooler only when reaching the operating temperature and second controls it during the ride.

Picture the set-up like this:

Now the focus is on how the oil shall flow. In a cold engine it looks like this.

The oil flows from the oil filter box of the engine through the hose into the external oil filter box where it is filtered. Then it flows on to the thermostat where it is immediately redirected into the engine until reaching the operating temperature.

Once the engine has reached its operating temperature, the oil is directed from the thermostat into the oil cooler where it is cooled, and from here back to the thermostat. Then it is conducted into the engine, where it immediately flows through the hose behind the cap into the main oil sump and lubricates the crankshaft.

That’s it for the theory.

As concerns the practice, but first and foremost the visual appearance, this solution is applicable to covered motorcycles as there the built-on components are not visible.

With naked motorcycles the hiding is a bit more difficult, one has to come up with an idea or live with everything being in sight.

A solution we devised could look like this.

Instead of the original one a self-made cap is built in that holds the oil filter and also serves as connection with the oil cooler.

Unfortunately, so far this idea only exists as a draft, but we are working on its realisation.