The KZ550GP is equipped with a large-size oil cooler, which is enough for a mini-bike, but when it comes to the extreme heat of the past few years, the current size of the oil cooler body is insufficient in capacity. So, we decided of installing an oil cooler kit for Zephyr 400 with the same series engine, but it was not so easy.
Here is a report on the realization of an idea to equip a large oil cooler.Let's try it.
Attractive large size oil cooler!
The challenge began with the installation of a Posh Faith oil cooler kit for the Zephyr, a 9-inch, 13-stage kit, which is almost the largest oil cooler for air-cooled multi-engine engines. I chose the smallest oil hose size (No. 4), so I installed an adapter to reduce the size from No. 6 to No. 4. The KZ550GP was equipped with a custom parts oil cooler for the Monkey. Among the first generation Kawasaki middle series, only the GP was equipped with a stock oil cooler. However, compared to the stock small cooler body, the cooler was nearly twice as large for the Monkey. The tuned engine required an even larger oil cooler.
Steering wheel offset is a problem
The first middle series to use a leading-axle bottom case. It features a small three-pronged offset for adjusting the amount of trail. This makes it physically impossible to install a large oil cooler, which is also a feature of the first-generation middle series.
Invent your own steering stopper!
With thin cardboard paper, scissors, and a circle cutter, I started making a pattern for the handle stopper. I tried to create a design that would be co-tightened with the brake line junction. After cutting out the approximate shape, I applied it to the front fork to check interference points and determine details such as bending points, etc. If you make one failed attempt, the second one will always succeed! Trying, again and again, will increase accuracy. Once the pattern is made, materials are prepared and the pattern is marked as a base. A 5mm aluminum sheet was cut out with a contour machine (band saw) according to its shape. Additional handle stopper to be co-tightened with the two M6 bolts that tighten the 2-way junction of the brake line.
Discreet black paint
The stopper brackets are cut from 5mm thick aluminum sheet according to the shape of the pattern, drilled and bent, sprayed with semigloss black heat-resistant paint, and then heat-dried in a Kerbeck CV Jr. This homemade paint finish also improves solvent resistance.
Sacrifices were made to make the dream come true!
The stay of the posh-faith oil cooler kit was tightened to the tightening seat of the stock oil cooler stay. The cooler itself is mounted on the lower stay only. The rubber damper works well without any wobble. When I turned the steering wheel after laying out the cooler body, the inner tube does not interfere with the cooler body and looked good.
POINT
Point 1 - Oil temperature is the key to engine condition in summer.
Point 2 - Knowing the proper oil temperature is also important.
Point 3 - Oil temperature can be monitored by installing an oil temperature gauge
The Kawasaki KZ550 has more torque overall and a wider range of gears with the inclusion of a bore-up kit, but before putting such a power upgrade into practice, we wanted to improve the engine cooling system. Compared to the stock KZ550GP, the KZ550GP is already equipped with an oil cooler that is almost twice as large as the OEM one, and the engine waist has been painted with gun-coat paint, which has definitely improved the cooling performance compared to the stock specification. However, recent summers have been extremely hot, perhaps due to global warming. Considering such an environment, we thought it would be better to further improve the cooling performance to enjoy the engine tuning plan later on.
I want to install a large oil cooler. However, for the first generation Kawasaki middle 4-cylinder series (such as the first generation middle series like Z400FX and KZ550GP), installing a large oil cooler is a big trick. The first generation series had a small offset of the three-way motors, so when the handlebars were turned all the way to the left and right, the inner tube and the frame were in close proximity! In other words, when a large oil cooler is installed, the cooler itself and the inner tube will come in contact with each other with a thud.
In order to get rid of such an obstacle, we decided to make a sacrifice and install a large oil cooler. This is the reason for the addition of a steering wheel stopper as reported here. This is the reason for the addition of a steering wheel stopper as reported here. Sacrifice refers to the steering wheel's turning angle. If the steering wheel angle is reduced, it may become troublesome when making a U-turn in town or when pushing the car around.
A bent steel plate was fixed firmly with duct tape in place of a stopper, and after imagining the decrease in steering angle, we confirmed that it was well within the tolerable range. Then, I decided to install a large oil cooler developed for Zephyr 400. Incidentally, for 4-stroke engines, warm-up operation is started by starting the engine from room temperature. To some extent, try to start riding when it is warmed up, wait for it to warm up further, and then turn the engine over comfortably. If you force the engine to run when the engine oil is not warm, you will damage each sliding part inside the engine. To avoid such a situation, it is convenient to have an oil temperature gauge that can monitor engine oil temperature.
Generally, the proper oil temperature is considered to be between 100°F and 125°F, but in summer traffic jams, the oil temperature often exceeds 130°F with ease. It is understandable that air-cooled engine models have a hard time in the summer. The running wind is very important.
