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Great Chemistry – A GPz550 Revival

The old GPz550 sat for years. Getting it up and running would take time, effort, and the right stuff.

1983 Kawasaki GPZ550 parked right side

I always enjoy the arrival of each Canadian Biker magazine, for the many insightful articles, stories, fun facts and farkles.  To be fair to the magazine, riders and the reader, I am a motorcycle enthusiast who does minimal wrenching primarily due to my pathetic mechanical skills, and will leave the real work to the professionals in my area. This is doubly true if/when the road devil strikes and has me sitting on the side of the road searching the GPS or smartphone for the closest service.

In the January/February issue, Rich Burgess shared his experience that all too often puts a motorcycle to rest: the leaking fuel tank (“Tough love for a bad leak”). In this Tech & Tools article Rich identified Red-Kote tank sealer to resolve the leaking fuel tank on his custom cruiser. Rich obtained the stuff from the manufacturer via eBay. 

All good. However, what got my attention was that his purchase “was delayed a couple days at the border, but was eventually deemed legal to enter.” There may be another option available to those of us in the Great White North.

Context: I purchased a used 1983 Kawasaki GPz550 in 1987. It was my first street motorcycle. It had been tracked, and in the hands of its current owner, had its share of thrashings, bumps, bruises and one good wipeout that saw my beauty slide along the pavement tearing off the points cover, sending plastic bits to oblivion, snapping off a mirror, the tail light and a good bit of flesh from my right knee.  Yep, still hear and share the words: there are two types of motorcyclists, those that have crashed and those that will. Once all the healing was done, and repairs to the GPz complete, we were reunited and back on the road.  That is until a hiatus and for nearly 20 years when I was blessed with a family and “free time” was filled with many non-motorcycling adventures.  Beautiful years and great memories.  

Fast forward to the winter of 2007 when free time was less of a mystery, and thoughts about riding the GPz became a priority. Gasoline, that marvelous cocktail derived from dinosaur stuff that propels the marvel of the internal combustion engine and us into a motorcycle state of mind, can be destructive when ignored for so long. The amount of rust and gunk that accumulated inside the GPz gas tank, fuel lines and carbs was astonishing. What a mess!  

1983 Kawasaki GPZ550 engine refresh

What to do? Send my classic ride to the motorcycle graveyard? Nope, let’s get it back on the road. The inventory of things beyond the tank restoration included a barn find donor bike, new rubber, seat recovering, wheel bearings, rebuild of all things around the brakes, fork seals, and a transplant of the carbs and mono shock from the donor bike.  The task of finding the “right” gas tank sealer scratched at my synapse. I cannot comment from personal experience with other gas tank sealing products, but friends and the kind folks at area shops did have an opinion or few that led me to Caswell Canada.  Among the many restoration products Caswell makes available to the public, they have a two-part epoxy gas tank sealer. Not only is it available in Canada, it has a low odour factor, avoids cross border stuff, greenback/Loonie exchange rates and the easy to follow instructions made the process a breeze.  

The step-by-step instructions provided by Caswell, online and in the packaging, are almost a match to the ones given in the Burgess article. One added step that may or may not have added to the positive results included the use of Evapo-Rust converter that can be found at Canadian Tire.  

Once all the crud and gunk were decanted, petcock, tank float and other bits removed from the GPz550 gas tank, the requisite shake-rattle-and-roll of drywall screws, nuts and bolts, and acetone cocktail treatments were followed. The generous helpings of Evapo-Rust converter treatments made the inside of the tank look like clean metal. Progress!  

After a few overnight Evapo-Rust converter treatments, the magic liquid was coming out of the tank almost the same colour it went in. Before applying the Caswell two-part epoxy, I gave the tank one more acetone rinse followed by an “air-dry’ aided with an old hair dryer and cardboard tube inserted in the fuel filler hole on a warm setting for about 15 minutes. Any use of the acetone was done in a very well ventilated area.  

With the epoxy applied, I made sure all threaded holes were cleaned up. While the epoxy was curing, I test fit each bolt and the petcock to ensure they turned freely and were not permanently bonded to the tank sealer.  Next was to allow the epoxy to cure for several days, and from there a rattle can paint job, reassembly and the re-introduction of the tank and fittings to the GPz. Ready to roll!

The results have held for almost 10 years, and I am proud to own a 34-year-old motorcycle with a non-leaking tank that gets on the road with each season. There are times when I feel like a circus bear on the diminutive GPz550, but getting on the throttle to redline feels as good now as it did in 1987.  

1983 Kawasaki GPZ550 parked left side

Thanks to the inventors of Caswell Gas Tank Sealer (, Evapo-Rust ( ), motorcycle friends/enthusiasts and Canadian Biker magazine, a classic motorcycle lives on. The 1983 GPz550 is as good as, or perhaps better than new. Special appreciation goes to Rob, the proprietor of Bytown Motorcycle Repair in Ottawa, for doing the wrenching. Now what to do with all those left over parts?

By Greg Leemans Canadian Biker Issue #329


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