TOPIC:

Has anyone installed smaller oil coolers than what came on the KZ750 + models?

I'm wanting to install something that fits more neatly than the factory oil cooler. So mainly something narrower.
I've cut my shortlist down to two - Yamaha XS750/850 or a Kawasaki KX450 (or possibly even one of the eBay specials...).

1976-1981 Yamaha XS750


2011 Kawasaki KX450


NEW eBay special



All these will even fit in between the front frame section (ahead of the motor and above the exhaust), making for a super neat install.

Any major concerns or red flags as to why these wouldn't work? (Fittings will obviously be made to match the GPZ750 oil pan)

I installed an oil cooler from an 82 Gpz750 onto my 810. Welded tabs to the frame and used tbe Gpz oilpan. It bolted right up and looks OEM.

baldy110 wrote: I installed an oil cooler from an 82 Gpz750 onto my 810. Welded tabs to the frame and used tbe Gpz oilpan. It bolted right up and looks OEM.

That's really neat! Definitely something I explored too, as you can get the whole setup at a reasonable price now too.

The look and positioning that I'm looking for is something more like this...



I'm just wondering if anyone has ant experience or knowledge on the coolers that fit in that space (that I listed) - whether I'm missing anything in this not being a viable option.

I also installed a stock GPz/L model cooler on my bike. It was a straight bolt on other than the cooler mounting. For that I drilled through the reinforcement plate at the head tube and used the stock rubber mounts . If your bike is using a mechanical tach you have to watch how tall the cooler is due to cable routing.

So you want the cooler more for looks than function. I consider the Gpz cooler pretty small. Any smaller and it wouldn't cool the oil much.

baldy110 wrote: So you want the cooler more for looks than function. I consider the Gpz cooler pretty small. Any smaller and it wouldn't cool the oil much.

Well this is the question I'm posing. Are these smaller coolers lacking function?
Seeing as Yamaha from the factory installed the first one I showed, on a 750cc and 850cc bike of the same era as ours, I'd suspect it has some level of suitable cooling?
And the other one from the Kawasaki is a newer design from only 9 years ago, so how efficient are they compared to the 40 year old design installed on KZs? Maybe smaller still provides a similar level of cooling from a smaller cooler?

That KX450 cooler looks to be built to survive crashing. Doesn't look very efficient due to lack of cooling fin area and thick wall between where oil flows and the fins.

Those are more heat sinks than coolers. There hasn't been much change in cooler design in the last 40 years.

I realised I never followed up on this in terms of what I decided.

I ended up sourcing a 1980 Yamaha XS850 oil cooler, which fit the dimension I was looking for almost perfectly.

End result is a neat and tidy oil cooler that, paired to a custom mount, sits comfortably above the exhaust, while remaining tucked away almost flush with the frame. Once I finish test-fitting all my parts, I'll clean and paint it so it's even more inconspicuous.


Front on, it's got a reasonable surface area, very close to what the GPZ cooler is, just in squarer proportions that I think are much neater for the bike.




Sits pretty flush. I originally wanted it to sit in that triangle in the frame, but it just wasn't to be. This feels pretty clean though.


Custom mount as can be seen from the back. Sits with plenty of room around it for airflow and soft-mounted for any frame twist.

I used one off a ducati monster. Fit perfectly and looks better than others.
Photos not working right now

Are you sure the downpipes(headers) are ging to fit under the cooler?I use a GPZ 550 UT oil cooler.

Yeah, it was all positioned with the top-end and exhaust fitted.
Initial plan was to have the plumbing sit at the bottom of the oil cooler for an even neater look, but that would have fouled on the headers, hence the 180 fittings on top instead.