Real Rides: Karl’s GT550

Dailies -

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01-600

The first such story in a new regular series, let’s take an in-depth look at a honest-to-god, real motorcycle ridden by a real reader. Karl is a 43-year old software engineer, avid car collector and longtime rider based in San Diego. This is the air-cooled, two-stroke, three-cylinder 1973 Suzuki GT550K he restored himself.

The Builder

Karl returned to riding after an 8 year break through the purchase of a brand new Triumph Daytona 675 jn 2008. After 18 months of riding, he wanted another bike, a “counterpoint to the 675,” as he said, and something that would slow him down a little, yet something that would still have a lot of soul. After a couple days of searching eBay and Craigslist for older Bonnevilles, Nortons, BSAs, Karl discovered that older Japanese bikes like Honda CBs and Suzuki GTs were much cheaper to buy and easier to come up with parts for. Eventually, Karl settled on this 1973 Suzuki GT550K he purchased for $700.

The Bike

The Suzuki GT550 series was introduced in the year of 1972 as a “grand touring” motorcycle. It’s an air-cooled, two-stroke, three-cylinder, 543cc machine that produces 48.5 horsepower and had some interesting technical specs at the time. The GT550 has an ram air system, an automatic mixing system for oil and gas and a unique exhaust system. The ram air system kept the engine from overheating by keeping the cylinder head cooler since two-strokes begin to lose power quickly if they overheat. The automatic mixing system removed the need of having to pre-mix oil and gas in order to prevent people from mixing too much oil in the gasoline. The exhaust system on the GT550 was unique for the time because the exhaust header was divided into two and exited into two separate mufflers. The GT550 was known as a good handling bike with smooth acceleration but was lacking in speed and style.

The Build

The condition of the bike was appalling when Karl bought it. No working brakes, the crank seals were finished, the chain rusted to bits with rotting tires. After going over the bike and seeing what needed to be done to get her just up and running again, Karl slowly to begin the enormous task ahead of him, the process rebuilding took over a year. According to Karl, most of that year was tearing the bike down to its nuts and bolts and replacing the old parts with new ones if there were available and old ones if they weren’t. He purchased a soda blaster, that made cleaning up the bike much easier. Karl opted to replace some of the parts with parts from another year to make the bike more pleasing to the eye.

He replaced the side covers with the ’75 GT550 version, which required him to weld in new tabs to hold them, a ’75 ram air cover and a chrome chain cover. He used eBay to purchase most of the parts. There was a sizable dent in the tank, which he repaired by sanding down the tank and filling up the dent with some Gold Standard Tank Sealer. He had to send the motor off to be complete rebuilt, with a new 120 crank, seals and ball bearings, doing the resealing and cleaning of the engine himself. He muddled his way through wielding crack in the aluminum case top and succeeded. He rebuilt the wheels with nickel plated spokes and had to rebuild them again two years later after they rusted apart, replacing those wheels with a pair of gold Sun rims. He ended removing the old ignition and replacing it with electronic ignition to keep the timing in check so the two-stroke could function properly.

Karl left the seat for last, having never built a seat himself, it took some research. He ended up carving a seat out of wood and making a mold out of fiberglass, putty and steel. After building the seat, he added a checkered racing stripe down the center of the tank and the seat. Not bad for his first time!

Several hundred miles after completing the build, he blew a hole in his center cylinder due to missing a partially blocked pilot jet. He bought a used cylinder from eBay, tore down the engine, cleaned out all the slag and got her up and running once again.

The Result

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“Power band is less pronounced on this 2 stroke than the H2s or RDs, but it definitely still comes on song at high revs,” describes Karl. “But what’s best about the ride is you can’t mistake it for a modern standard either as a rider, nor as an observer.”

Want to see your bike on HFL? Email info@RideApart.com with a few pics and words and, if we like it, we’ll contact you about creating a story.

  • http://www.facebook.com/davidabl.blankenhorn Davidabl Blankenhorn

    “Karl discovered that older Japanese bikes like Honda CBs and Suzuki GTs were much cheaper to buy and easier to come up with parts for (than Bonnevilles, Nortons, BSAs)” Really? I’d like to know if parts are really readily available for the more obscure Japanese bikes like Karl’s GT.. Obviously you can get repop parts for CB’s or Yamaha XS650′s about as easily as for old brit bikes but for GT’s??

    • http://www.facebook.com/people/Scott-Sweeney/501437288 Scott Sweeney

      True it’s no CB but I think that goes to show you just how much harder to get and pricey classic euro bikes and parts are.

    • Scott Jameson

      E-bay & the internet revolutionized vintage motorcycle ownership.
      BMW is reliable brand to source vintage parts.

    • karlInSanDiego

      I was surprised too. Some are Suzuki parts still being sold through the dealer networks, a mix of nos and ancient old stock . Not many repro parts at all for GTs, but lots of decent used equip from low mileage bikes (mine had only ~12k). Search GT550 on Ebay, but be sure to filter past Kawi parts of same name. Exhaust is the hens teeth of this bike, as they’re all rotten, so many go with custom spannies. Stockers were expansion chambers though it’s not easy to tell. I won a second set of these elaborate stock pipes (actually 3 into 4) for $1 on ebay with free shipping! Mostly as rotted as my first set.

      • nick2ny

        Doesn’t NOS mean AOS?

  • http://twitter.com/Mr_Paynter Bryan Paynter

    You have to love straight-forward honest motorcycles.

    • Ben Wipperman

      Much as I hate being told what to do – you’re right. I love it and have no say in the matter. Damn.

  • Scott Jameson

    Good piece, Daniel, thank-you.
    “Want to see your bike on HFL? Email info@RideApart.com with a few pics and words and, if we like it, we’ll contact you about creating a story.”
    Looking forward to this…

  • karlInSanDiego

    Thanks for the writeup, Daniel. A few minor corrections: The pipes are 3 into 4 (center pipe siameses into two) which Suzuki did on all their 3 cyl bikes for visual balance. Tank sealer actually went into the rusty tank, bondo on the outside. I built the motor (2 strokes are dead simple) but sent that 120 crank out to be split, resealed and rebearinged, and reassembled. It’s the one good job to leave to a specialist (Bill Bune) with these bikes, because they sourced and machined (pinned) some hard to find bearings, and are experienced at pressing the crank back into its unkeyed 120 degree positions. At first they balked asking me to send them all the parts, but eventually, they came through and sent back an awesome crank/rod assembly.

    • http://www.facebook.com/daniel.joshua.silverman Daniel Silverman

      Glad you liked it, Karl!

  • Eddie Smith

    Great looking bike, better than new. The old two strokes were classy, lightweight and quick enough to get the job done. 3 cylinders, 4 pipes, what a brilliant idea…

  • Kr Tong

    I just made an F4i out of two crashed F4i’s I pulled off craigslist. Hardly even threadworthy on the local forums, but considering I spent $900 in total including tools and towing, and it took me four nights to make it run, I think I made out like a bandit.

    • http://twitter.com/Mr_Paynter Bryan Paynter

      I really, really want to see a thread of this.

  • http://www.facebook.com/mattcmason13 Matt Mason

    Great Story! I look forward to the rest of the series!