Adding an oil cooler on a kz650

Hey guys,
I'm adding an oil cooler on my 1980 kz650e ltd. I am putting the wiseco k700 big bore kit on and think it may be a good idea for insurance when it gets hot in the summer here. I have the deRale 180° thermostat and the oil pan, lines, and cooler from a ZR750 zephyr that I plan to install. The question that I have is, will the oil sump that I currently have be adequate to run oil through the cooler? I've seen some people are using the oil pan from the early 80's GPZ's. When I look at that oil pan I see the oil sump is bolted in from the bottom. The pan that I have, has the ports for oil cooler lines, but not the hole in the bottom for an outside bolt on sump. I've been reading in my 79' Clymer manual ( I know some people hate them) that you can use a .060" shim on the pressure relief valve to "upgrade" the pump for this kind of modification. Since this is a 79' manual the oil pans for the 80's GPZ's and 90's zephyr hadn't come out yet and I assume they were talking about the lockhart conversion kit. Has anyone else done this upgrade with the ZR750 oil pan?

Don't know much on the oil cooler and pan but I have the same Clymer manual and asked about adding the .060 shim to the relief valve like it says and all the guys that responded told me it sounded like a bad idea and to stay away ......... interested to see if anyone's did it or changed there mind since it was many a year ago.

Search for "ZR7 motor in a KZ750" it will lead to info on installing a ZR7 oil pump that will be a improvement for ya.... I have not done it but a few on here have and sounds really good.

I put a cooler on my '81 750 by installing an early GPz pan and a cooler off a 700. Everything was a straight bolt on other than I had to fab some cooler mounts which was easy. One problem with the later cooler is that it's larger and will block a mechanical tach if you happen to want to run one. In terms of the oil pump and relief valve, your bike comes with the same pump and relief valve as lots of other bikes that came stock with coolers so you should be okay. Only caveat is that the ZR7 cooler is quite large, and the ZR7 did have a different pump. You might want to consider using a smaller cooler just to be safe. The bike will run plenty cool.

Do you happen know the dimensions and capacity of the oil cooler you used? I was kind of surprised with how small I believed the one I have is. The one I have measures roughly 10.75 x 4.25 x 1.5. I'm unsure of the capacity. I know I'm going to need to get more oil line to put the thermostat on. Is there a certain diameter of hose that I have to have to maintain appropriate oil pressure?

This is slightly off of topic; when I went to take the cylinders off of my bike to have them bored there was a bunch of dirt that fell through the stud holes and some of it into my crankcase past the pistons. I'd really like to not have to split the case. I've heard that I have 3 different options to try to flush out the case. I've been told I can use diesel, kerosene, or filter some old oil and pour it through case to flush it out. In the event I use diesel or kerosene I was told to make sure that I get all of it out that I can and be sure everything is re-lubricated because it can wash the oil out of the crank bearings. Does anyone have any thoughts, ideas, or opinions on this?

I did the same thing so I rigged up a auto engine stand on the rear of the motor (with info on here) took the pan off and sprayed it out with wd-40, brake cleaner and a little gas the first time. I know bad idea on the gas and would stay away from that and start with your plan. By spraying it and flipping it over 4-5 times I got it really clean and hitting it good with 10/40 after and spinning it over with the plugs out after the build to build oil pressure I felt good with mine.

The lines that I'm using from the zr750 have a much longer length of metal tubing than hose. To attach my thermostat onto the lines I need to cut out a section of the metal lines and add more pressure hose. Does anyone know if the pressure that the lines are under is too great for hose clamps, or what I should use to make this kind of splice. I've been doing some research and just haven't been able to find what would work best for this application. You guys have been more than helpful. Thank you. I think my bike is going to end up with very similar specs to yours KZB2 650. I'm excited to see what kind of power I gain.

Do NOT trust hose clamps to hold. If a hose was to pop off while you are on the highway your engine will surely suffer and so will you when your rear tire drives through your own oil slick.
I used a zr550 oil cooler (same part number as the cooler used on the Zephyr 750 and the zr-7)
and oil lines with a zr-7 oil sump. I had to shorten the rubber section on the lines and had a company that specialized in making and repairing hydraulic hoses cut me some new shorter lengths of hose and crimp them to the metal lines. Tractor supply/part stores or shops that specialize in A/C lines could also help you out.

Many (and I MEAN many - see pic below) years ago I owned a 350cc BSA. Its oil was in a tank rather than an oil pan, and that oil was then pumped between the engine and the tank through hoses. Those hoses were held in place using hose clamps - until one night when the hose clamp on return hose let the hose come off the fitting. That engine seized up so tight that it could not be repaired for a reasonable sum of money. The lesson - don't trust hose clamps when it comes to the life of the engine. Ed

Hose clamps will work for low pressure applications, such as for a cooler on a roller bearing crank engine like the KZ900/1000. The 650/700/750 4-cylinder bikes use a plain bearing crank though and require a high pressure oiling system. No hose clamps in that application if you know what's good for you.

Regarding a thermostat, Kawasaki didn't use one on the KZ bikes that came stock with oil coolers . Adding one to a bike while good in theory may not be worth the effort.

Well hose clamps are definitely out then. If anyone knows of a high pressure application adapter that will work that would be helpful. I've sent an email to DeRale to fi d out if they offer a version of such a thing and am waiting to hear back.

About the thermostat, I had read several posts on here that said something to the effect of it being almost necessary to use one because the motor temperature wouldn't get warm enough to evaporate the water out of the case if it were constantly flowing through the cooler. Is this not the case?

If you live near a reasonably large city, there probably is a hydraulic hose company that will make whatever you want.