Most adjustments and maintenance procedures for the TK-26 carbs can be found in the Factory Service Manual, or other service manuals for the KZ550 motorcycles. This page will only expand on some of the details, make corrections, or give some miscellaneous information not covered in the manual.

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Fuel Level

The service fuel height for the TK-26 carbs are specified two ways. One is in mm of fuel height in a clear tube. This is where a clear tube is attached to the drain port of the carb and the carb is allowed to fill up. The tube is placed next to the carb when the carb is level so the level in the tube shows the level in the bowl. The bottom of the meniscus should be about 7mm below the bowl mating surface.

The other way to set the fuel height is less accurate, but more convenient, especially if the carbs are already taken apart. That method specifies the height of the float above the bowl mating surface when the carbs are upside down. The height is measured when the tongue of the float frame just barely contacts the tip of the fuel valve needle. The height specified is 27mm. It has been found experimentally that 28mm seems to work better nowadays. Perhaps ethanol is lighter than gasoline. That could explain the difference.

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A Quick Note on the Dreaded Air Box

The airbox on the 82/83 Gpz550 is a 3-piece unit. The left side of the bike has a large, obvious air filter attached to the airbox. However, the right side also has a small triangular air filter, which is not so obvious. This should be inspected and replaced as necessary.

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Maintenance and Tools

Here are some tools that might come in handy for working on the Tk26 carbs.

First up are some tools for syncing the carbs on the bike. The sync screws and locknuts (8mm) are a long reach when on the bike, but some cheap home-modified tools can make it easy. First you need a couple specific screwdrivers. One is a multi-driver usually available at home centers. This Buck Bros., orange-handled screwdriver is useful because the main steel tube has a hex shape at each end, which is probably nominally 5/16", but fits the 8mm locknut of the sync screws nicely. They don't need to be very tight, as a matter of fact they will strip out the aluminum linkage if care is not taken. (See the repair done near the end of this page.)

To use the driver, the detent ball and spring must be removed. There may also be some sort of plug near the spring and ball in the middle of the hex tube. The hex tube has a narrow section in the middle that must be opened up for the screwdriver to fit through. A 1/4" drill bit, inserted through the hex tube the long way, works well to drill out the center section of the tube. Be careful to drill with little pressure as the drill bit may get entangled with the spring and or ball bearing. It is probably best to drill a little bit from each end of the tube. Drilling the tube can be tricky so use a vise grip or something to hold the tube rather than bare hands. After drilling, the spring and ball can be pushed out.

Then an appropriate, long skinny screwdriver can be used through the center of the hex tube. To ensure a decent grip on the hex tube, a large nut was heated red hot and pressed onto the tube. Finger tightness on the large nut is all that is needed to lock the sync screws.

Make sure the screwdriver you select fully seats into the sync screw as seen below.

The hex tube slides over the nut while the screwdriver is engaged with the screw. This makes syncing much simpler.

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Here is a set of tiny bottle brushes that proved very useful for cleaning out the bleed pipes and jet galleries.
It is from American Science and Surplus, so they should be readily available online.

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Sync Linkage Repair

One problem that may arise on the TK26/27 carbs is a stripped throttle-sync linkage. The sync screw is M5 x .5 , which is fine thread. The screw threads into an aluminum linkage, which can get stripped out if too much torque is used on the lock nut. One solution is to use a 1.5mm to 2mm steel, threaded backing plate. By threading the plate, and inserting the plate directly under the aluminum, the sync operation will funtion exactly like it originally did. This will require a special tap as it is not a common size. McMaster Carr does carry them. It is important that the plate is wide enough so it won't spin under the linkage, but it must not protrude very far from the side nearest the carb holder, as it may interfere when the throttle is opened. It must also be thin enough to allow enough movement for syncing in either direction, but thick enough not strip out easily.

Click on the images below to get a closer view.