1966 Triumph TR6SR
Engine: 649cc air-cooled OHV parallel twin, 71mm x 82mm bore and stroke, 8.5:1 compression ratio, 40hp
Top speed: 96mph (approx.)
Carburetion: Single Amal Monobloc 1-1/8in
Transmission: 4-speed, chain final drive
Electrics: 12v, Tri-Spark electronic ignition
Frame/wheelbase: Single downtube cradle frame/ 55.5in (1,410mm)
Suspension: Telescopic front fork w/hydraulic damping, swingarm rear
Brakes: 8in (203mm) drum front, 7in (178mm) drum rear
Tires: 3.25 x 19in front, 4 x 18in rear
Weight (dry): 365lb (166kg)
Seat height: 30.5in (775mm)
Fuel capacity: 3.5gal (13.3ltr)
Make no mistake: kids are impressionable.
When Tom TeRonde was 11 years old, his dad bought him a Honda CB160 to tear around the family property on the outskirts of Oostburg, Wisconsin, where they had a few horses and grew Christmas trees. His four sisters were into the horses, leaving Tom as the only one in the family curious about internal combustion engines.
“Boys would often come around to hang out with my sisters,” Tom says of his young family life. “And I clearly remember one day when three guys pulled up on two Triumphs and a BSA. That made quite an imprint on me. I hoped that one day I could get something like one of those Triumphs — it was the sight and the sound, and I thought it was a very cool way to get around.”
Better than the small-bore Honda, at least, but Tom had to wait until he was 19 before an opportunity to acquire a Triumph presented itself. In 1977, Tom had just finished his first year of school at the University of Wisconsin. He went to visit a high school friend who happened to be selling a 1966 Triumph TR6SR.
The sidestand lug was broken off the frame, so it could only be parked on its centerstand. The speedometer didn’t work, and there was no air filter. The distinctive Triumph badges and knee pads had been stripped off the tank, and it was painted white with stylized green flames.
“I could look past all of that,” Tom laughs, and adds, “He told me he wanted to sell it because he found it hard to start. I asked how much he wanted for it and the price was $300. I told him it was sold.”
Tom had been saving money doing roofing work and that’s how he paid for the Triumph. Apart from the Honda CB160, he’d never had or ridden a larger machine, but the Triumph, which he didn’t find to be a recalcitrant starter, soon became a constant companion. He’d ride it from his home near Oostburg to campus in Platteville, a distance of some 200 miles. That wasn’t a daily journey — only during semester breaks. When he finished his degree in radio and television broadcasting, a field he never did work in full time, he regularly used the Triumph for the next 20 years.
By the late 1990s, though, there was an accumulation of issues that forced Tom to park the Triumph. None of them separately would have been deal-breakers, but the clutch was slipping and one of the header pipes was loose at the exhaust spigot and he couldn’t get it tightened down.
“I thought enough with the minor annoyances, and started dismantling the motorcycle,” Tom reports. “But I’m no mechanic. I can get stuff apart, but getting it back together is another story. I realized soon I was in over my head.”
Cardboard boxes filled with parts and a bare frame were constant reminders to Tom of his “sweet, old motorbike.” He needed to find a mechanic, and through a friend of a friend, came up with an arrangement that saw him deliver the components to a backyard workshop. This didn’t turn out well. “After a year and a half of excuses, I showed up and think I got most of the parts back — it was hard to tell if anything was missing,” Tom says.
Triumph model development
Triumph’s TR6 was introduced in 1956 as a sporting machine aimed at the West Coast desert racers. Before delving too far into the TR6, however, let’s look back into the development of Triumph’s 650cc twin.
Prior to 1950, when Triumph released its 650cc 6T model, the manufacturer had only the 5T Speed Twin, developed by Edward Turner and introduced in 1937, and the T100 of 1939 as the largest bore machines in its range. Both were 500s. Immediately after World War II, dealers and customers alike were requesting that Triumph create a larger motorcycle, especially in North America where wide-open spaces and long, lonely roads taxed a 500cc machine. Turner didn’t immediately see the merits in boosting the engine capacity of his parallel twin engine, but he finally acquiesced.
On the inside cover of a circa-1950 Triumph brochure, copywriters wrote: “1950 will be notable as the year of the production of a new model to be known as the ‘THUNDERBIRD,’ a 650 c.c. (40 cu. in.) high-performance motorcycle suitable for solo or sidecar, which we are confident will be as popular as the now classic ‘SPEED TWIN.’ The new highways being engineered all over the world demand even greater performance and reliability, and the ‘THUNDERBIRD’ has been evolved to meet these modern requirements.”
Triumph’s parallel-twin 650cc engine featured a three-piece crankshaft with a central flywheel turning on roller bearings at each end inside a cast aluminum crankcase. Alloy H-section connecting rods with plain, or Babbitt-style, bearings had an 82mm stroke and cast-iron barrels had a 71mm bore, providing an overall capacity of 649cc with a 7:1 compression ratio.
Geared camshafts, taking their cue from an idler gear turning on a pinion gear affixed to the right-hand side of the crank, rode high in the horizontally split crankcase, inlet cam to the rear and exhaust cam to the front.
The air-cooled 649cc twin puts out about 40 horsepower, plenty for a bike weighing just 365 pounds dry.
A cast iron cylinder head had valves enclosed by cast alloy rocker boxes with an overhead oil feed taken off the scavenge side of the lubrication system, as oil was returned from the dry-sump crankcase to the external oil tank. The inlet cam drove a plunger-type oil pump. Ignition was by magneto, located just behind the cylinders, while electrical current was produced by a dynamo mounted in front of the engine.
A right-side foot shift lever stirred the gears in the separate 4-speed transmission and a 5-plate clutch lived under a highly polished primary cover on the left side of the engine. Power was transmitted from the engine to the transmission by chain through a ramp-and-spring cush drive sprocket to the clutch. All of these components were placed in a rigid-style frame with a hydraulic fork up front.
Triumph’s Thunderbird proved to be a successful motorcycle, and in 1954 the company took the concept a step further and introduced the T110 with a revised cast-iron cylinder head, higher-compression pistons with a ratio of 8.5:1 and a larger Amal carburetor. Also new was the swingarm frame and at that time, the T110 was Triumph’s fastest 650cc production motorcycle.
The Trophy models
The TR5 Trophy debuted in 1949. Based on the Speed Twin and its 500cc engine, the Trophy had a high-level exhaust and the all-alloy, square-barrel top end from Triumph’s WWII generator engine, and in 1951 the model was equipped with revised close-fin alloy cylinders and head.
Then, in 1956, Triumph offered the 650cc TR6 Trophy, an offroader equipped with the larger single-carb 649cc engine of the T110 Tiger but updated with an aluminum head and 8:1 pistons. The Trophy was in essence a street scrambler that could be ridden to work during the week and then, come the weekend, on the dirt thanks to a quickly detachable Lucas headlight, high-level exhaust and moisture-proof magneto.
The TR6, like the 6T before it, sold well in the U.S., and the model was spun into three derivatives: the TR6A, with freer-flowing low-level exhaust pipes and a tachometer; the TR6B, with a mid-level 2-into-1 exhaust setup and no tachometer; and the TR6C with the exhaust system of the T110 and no tachometer. By 1958, the TR6’s alloy cylinder head was slightly altered and, according to author Ian Falloon in his book The Complete Book of Classic and Modern Triumph Motorcycles: 1937-Today, was available only as the TR6A road-going model and the TR6B “scrambler” machine.
Triumph’s big news for 1959 was the introduction of the sporting twin-carb T120 Bonneville. The TR6 Trophy would then after be known as the single-carb machine, but apart from the number of carburetors, the two models were similar in specification.
By 1963, the year Triumph moved from separate transmission/engine construction for its 650cc machines to full unit construction, the TR6 was offered as the TR6SS (siamese, low-level exhaust), TR6SR (separate low-level headers and mufflers) and the TR6SC (with separate high-rise headers and mufflers). All TR6 motorcycles used the new-for-1963 single-downtube frame, which offered increased rigidity compared to the duplex-frame of 1960 to 1962.
The engine cylinder head increased from eight mounting studs to nine to address an issue with combustion chambers which occasionally cracked. The rocker boxes sprouted fins around their bases and the inspection caps shrank in size. A 2-row primary chain was included, the magneto dropped, and coil and points ignition took on the job of making sparks.
The last year for the TR6SR designation was 1966 — the year of Tom’s machine. After that, the “S” was dropped and in the years following it was the TR6, TR6R and TR6C.
For 1966, the TR6SR had a 3-1/2-gallon slimline gas tank with new “eyebrow” Triumph badges and a parcel rack screwed to the tank top. Instead of a 6-volt electric system, the voltage had been increased to 12 and was regulated by Zener diode with a finned heat sink mounted to the front fork, immediately below the headlight. In 1966, the TR6SR was available in Pacific Blue and Alaskan White and the twin saddle featured a gray top and white ribbing. The fenders were painted white, accented by a blue strip lined with a gold pinstripe. The single-carb TR6 continued until 1973, when it was dropped from the Triumph range.
Going back together
Tom’s 1966 TR6SR was not a stock motorcycle when he had it. He remembers it with a taller handlebar and custom paint job, and he wasn’t fussy about it going back together to original specification — he just wanted to ride it. That’s when his nephew, Ben Burr, suggested Tom visit with Brady Ingelse of Retrospeed in Belgium, Wisconsin.
“For a brief while, Ben worked at Brady’s shop,” Tom says. “I went to visit Retrospeed and realized this is where the bike needed to be. As a roofer, I’ve always been a fan of bartering for labor,” he continues. “Brady’s house needed a new roof. I put a roof on his porch and dropped off what remained of my Triumph at Retrospeed.”
Brady picks up the story. “The project came in with multiple gas tanks and raw steel fenders and the frame had been painted,” he says, and adds, “Tom wasn’t concerned about the bike being original, so we had quite a bit of freedom.”
The entire time Tom owned the bike it never had a kickstand, as the mounting tab had long ago broken away. That was one of Tom’s only three requests — he wanted a sidestand. As Brady explains, that’s not as simple as it sounds. “You need the weight of the engine, the forks and shocks have to be mounted and the motorcycle has to be together and on wheels before you can determine the correct lean angle.”
As pieces of the Triumph were restored, the TR6 slowly took shape as it was loosely assembled to ascertain the lean angle.
As delivered, the top end of the engine had been removed from what looked to be an unmolested bottom end. Regardless, the engine came apart and it was determined that early on in the bike’s life there had been some aluminum repair to the cases. The cams were shot, the cylinder bores needed attention and the valve guides were cracked, however the crank journals looked good after a polish and the connecting rods, with new shell bearings, were returned to service. From the bottom to the top, Retrospeed went completely through the engine, correcting all that ailed it.
Of all the gas tanks Tom dropped off, Brady found none of them had the mounting points for a parcel rack — and Tom wanted that rack, the second of his requests. Brady purchased a 3-1/2-gallon tank with the threaded bungs to secure the chrome grid and proceeded to clean up the dents. He also lined it with a Red-Kote tank sealing kit.
The forks got new stanchions, and the lowers were powder coated black. Out back, Hagon shocks went between the rear subframe and the swingarm. Stainless-steel spokes from Buchanan’s Spoke & Rim were used to lace the silver powder coated hub in the front and the black powder coated hub out back into new chrome rims. Duro tires went on, front and rear, and the brake shoes were renewed. All control cables were made by Retrospeed. The last of Tom’s three requests were the tall, almost mini-ape-hanger handlebars that his bike had while he’d ridden it.
A replacement sidestand and tab were sourced from Mitch Klempf of Klempf’s British Parts. With the lean angle ascertained, the C-bracket of the tab was hammered around the perimeter of the lower frame tube before being welded in place.
From that point forward, the TR6SR came together rather quickly with fresh Pacific Blue and Alaskan White paint applied to the gas tank and fenders by Bill Krzyzanek of Kaliber Collision Repair in Port Washington, Wisconsin. To finish off the paint work, Allen Beck of Beck Lines in Ozaukee County pulled the gold pinstripes. An aftermarket seat was sourced, a new Amal Monobloc carburetor was mounted to the intake manifold and a replacement EMGO exhaust system was installed. For reliability, a Tri-Spark solid state ignition system was added.
Tom stopped into Retrospeed once in a while to see the progress, but he let Brady take his time with the project. Through all the years since 1977 when he bought the Triumph, Tom never owned another motorcycle. He rode it for close to 20 years, and it had been apart for close to 20 years. So, more than 40 years later, as of this writing in June 2019, Tom has been reunited with his Triumph.
He says, “Now that it has been restored to showroom condition, it is a bit surreal. For sure this is the same bike I used to have, but now with better than original electrics, new tires, new everything — it’s just amazing and a joyous experience to ride.”
Holding up his end of the bargain, Tom will replace the remainder of the roof on Brady’s house. And, perhaps recalling the lads who once pulled up to court his sisters, Tom concludes, “A big British bike this old has a style and a feel that is one of a kind. I’m so grateful for getting to have that experience all over again. Life is good.” MC