TOPIC:

Hey guys. I am in the process of organizing the parts I want and need for my rebuild of my 82 kz1000. One of the things on my list is an oil cooler.

I have heard various opinions on whether or not the oil cooler actually works or not. Some argue that the cooler on the KZ doesn't really work because there is the same amount of pressure in both oil lines so no oil actually get circulated through the cooler.

Others say they have noticed a considerable difference in engine temps when installing a cooler, especially in stop and go traffic in hot weather.

I would like to hear what you all think or know from experience before I add this to the list of things for my bike. I had a Honda once with overheating issues and never want to deal with that again.

Thanks.

If in theory with the pressure supposedly equal, then no flow. the cooler would stay a low temp compared to the rest of the motor after warm up.
It sure works great on my 82 KZ1000 LTD, I've checked the temps with a Inferred gun. You can see the temp difference top to bottom, etc. If you ride in +80 degrees in the summer, than I would say it would be worth it. Z1 has some fittings for some models.

The 80's GPz's(the 750,I think, but it was on the 1100's) and worked good.

YES. MASSIVE difference to oil temps when measured any way you like, in some cases the oil ends up too cold taking a LONG time to warm to operating temps. Equal pressure both sides???What the? The pressure doesnt matter its all about flow and heat transfer. Oh, ane one other thing, there is some concern in regards to the oil draining back down to sump and leaving extended time for oil to reach top end if you leave your scoot to sit for extended periods.
Cheers,
Kt

There are two kinds of cooler setups: series and shunt. In series nearly all the oil goes externally through the cooler. The aftermarket shunt coolers sort of "tap off" a bit at the high pressure output point where the oil pressure sending unit plugs in. A part of the oil flows out and through the cooler and returns to the pan so cool oil mixes with hot oil down there.

Oil coolers definitely work. back in the days before synthetic oil, they were mandatory in super high performance or severe service applications to keep the oil from breaking down rapidly. Now that synthetics are available, I think they are not required.

If you really need an oil cooler, they can be a good investment. There are some negatives.

Even the versions with a thermostatic bypass cool the oil more than without a cooler. If you run in cold weather, it can take a long time (or never) to reach optimium oil temperature. If you start seeing milky white oil in the oil level window, your oil isn't getting hot enough to burn off the condensation. In cases like this, you can cover the front of the cooler to stop air passing through it.

If you have the oil fittings at the bottom of the cooler, the oil will gradually drain back into the cases. When you first fire up an engine that's been sitting for a while, it takes a fair few seconds before oil flows to the cooler and back to the engine.

Oil pressure can be reduced slightly as the pump has to push the oil much further.

Riding in central california summers where it routinely reaches 100-110 for days or weeks on end. Would this be a sound investment for my 79 650 and will the cooler from a larger bike even adapt to mine?

Ktm181 wrote: YES. MASSIVE difference to oil temps when measured any way you like, in some cases the oil ends up too cold taking a LONG time to warm to operating temps. Equal pressure both sides???What the? The pressure doesnt matter its all about flow and heat transfer. Oh, ane one other thing, there is some concern in regards to the oil draining back down to sump and leaving extended time for oil to reach top end if you leave your scoot to sit for extended periods.
Cheers,
Kt

Pressure certainly does matter. Nothing flows without a pressure differential.

Finally, a question i can answer with experience!

Yes, they will make a big difference, i don't know just how much on our oil cooled bikes but a friend who used to race a Fireblade (CBR1000RR) had probs with the oil heating up that much it was actually breaking down gradually & they were having probs with engine wear. They removed the race kit radiator & added an oil cooler instead (std radiator was refitted), the same as bountyhunter describes, the one that 'taps a bit off'. Their engine wear problems disappeared & sometimes they had to tape off some sections of the oil cooler to get proper operating temperature.

Back in the mid 80s I was coming across the Mojave desert at 117 degrees & 80 mph and the heat was flat pouring off the cooler on my 82 GPZ750. I wouldnt have been a bit surprised to see it melt down into a puddle of aluminum. My stock 80 KZ1000 doesnt appear to need one but my 78 with the 1105 puts out a ton of heat in the summer. I dont think a stocker needs one but a big bore motor might

::pokes head in the door...looks around...then quietly takes a seat in the corner to listen to the discussion::

Oh & im installing one on the ZX6R over the winter, its a Track only bike though