TOPIC:

As Kawboy (I believe) suggested recently, Kawasaki would have designed the OEM fan for optimal performance. If a 5 or six bladed fan would have performed better it stands to reason that's what they would have produced. Frankly, I don't see how a different fan blade could move any more appreciable volume of air. The 4 blade OEM moves a tremendous volume of air!
With respect to Muzzy - If their "1300" fan was made for our machines there would be no need to "bush" the hub as it's been noted.
Kawasaki had their challenges right rom the get-go in that the frame restricts the size of the fan assembly. I'd guess that 2/3 or more of the rad. area is outside of the fan pull-area. The four corners of the rad must rely on static air to cool and this cooling is dependent on how fast your moving. We all know what happens when we're in slow traffic!

There's more to fans then simply cutting out the shape. Getting the pitch identical on all the blades is just one obstacle. And what pitch angle? Too little - less air. Too much and the electric motor will be working harder which would effectively slow it, draw more current and move no more greater volume of air. Getting the entire assembly balanced is critical to preserve the electric motor bushings/bearings. A model airplane propeller balancer could deal with the balancing potentially but the complexity comes in determining where to remove material to facilitate the balancing. Do you remove material from the blade-end, leading edge or trailing edge? I have some experience with this in mind and trying to balance a 5/6 bladed home-made fan would be truly frustrating and likely unsuccessful in the end. Another equally difficult issue would be the hub. Getting the hub perfectly centered and aligned axially and radially would be daunting, at best. There are countless inexpensive electric heaters sold with 5/6 blades with the correct diameter. The problem is the hub bore diameter and the hub off-set which must be identical to the OEM fan to ensure the blades clear the rad and the electric motor. The odds of finding one that just "slips-on"out-weigh the practical effort in searching and if one existed it seems reasonable that it would have been noted here or elsewhere.
A manual switch for the fan has and remains to be the best option for simplicity and effectiveness. An additional option which works to a noticeable degree (no pun intended) is to wrap the collector only (DG or similar 6 into one) with a header wrap from the front of the collector all the way back past the oil pan to the first bend. I've just done this and it works. I double wrapped with a 2" high quality wrap. Note: I did this with the header/collector on the bike and it took several attempts to get the over-laps and coverage correct. It now takes considerably longer for the oil-temp to rise and keeps the oil 5-10 degrees (measured) cooler. This doesn't prevent the engine coolant from getting up in temp but it cools off quicker when the speed is back up to move the static-air through the rad. and under the oil pan Given the surface area of the collector, it's proximity to the oil pan and the tremendous heat it puts off - one can appreciate how the header cooks the oil through the oil-pan.

I've given this topic lots of thought over the years and my personal assessment is to Leave The Fan As Is, install a manual fan-switch, wrap the collector, ensure the cooling system is clean and "burped" and run the correct mixture of coolant.

I tend to agree with Scotch's assessment and would add that a bottle of Redline Water Wetter has worked wonders on various bikes including my 300 RWHP ZX12R which no longer overheated in traffic after adding it to my coolant. The fan switch helped greatly, but the WW sealed the deal. Cheap and simple.

www.amazon.com/Red-Line-80204-Water-Wetter/dp/B000CPI5ZK

A friend of mine who operates the 1300 with a sidecar has installed a fan that blwos the hot air out of the carburettor area out to the side. With a manual switch of course.

He says it works well.

Other I know have installed small sheets on the frontside under the fule tank which "improve" the flow of air under the tank.

I am glad I do not have any issues, this seems to be a tricky one.


regards,

Holger

Just for fun I took a ZRX1200 rad fan and shroud and retrofitted it to the fan shroud on my B2. It was a bit of work but I'm happy with the end result. The whole retrofit I decided to do just because I could not because I thought it was necessary. Check out the post #7951 for the beginning of the Fan mod.

www.kz1300.com/index.php/forum/bike-proj...a-1980-kz13?start=12

My very first post here. I am familiar with the so-called "Muzzy fan". It isn't special at all, it IS a fan available here for low dollar from appliance repair facilities, better hardware stores and over the internet, eBay. They are fans from all sorts of appliances, used to cool things like compressors in refrigerators, freezers, all sorts of things. All Muzzy did was find one with more blades, angled close to the stocker, that fit the shroud, made a home made mount, and gent to town with them. He mostly sold them not for the KZ1300, but for other liquid cooled Kawasaki, Yamaha and other bikes. I found one decades ago for my KZ1300, they help when the rest of the cooling system is done up correctly, and the engine tuned right.

That is indeed true, I use the exact same fans in my job as a refrigeration engineer, they are available for a couple of quid (or bucks ). I have mentioned this in the past And I agree, they are unnecessary if you keep your cooling system serviced correctly.