1968 Yamaha YR2C
Engine: 348cc air-cooled 2-stroke piston-port parallel twin, 61mm x 59.6mm bore and stroke, 7.5:1 compression ratio, 36hp @ 7,500rpm
Top speed: 96mph (period test)
Carburetion: Two Mikuni 28mm
Transmission: 5-speed, chain final drive
Electrics: 12v, coil and breaker points ignition
Frame/wheelbase: Dual downtube steel cradle/53.2in (1,351mm)
Suspension: Telescopic forks front, dual shocks w/adjustable preload rear
Brakes: 7.2in (183mm) TLS drum front, 7.2in (183mm) SLS drum rear
Tires: 3 x 18in front, 3.5 x 18in rear
Weight (w/half-tank fuel): 361lb (164kg)
Seat height: 32in (813mm)
Fuel capacity/MPG: 3.8gal (14.4ltr)/NA
Price then/now: $840/$1,200-$3,000
Collectors and restorers of old vehicles are always on the lookout for that elusive “barn find.” We dream of finding an old bike tucked away in a forgotten shed or barn, just waiting for us to come along to awaken it from its years of slumber. It’s as if it was our destiny to cross paths with these long-lost machines.
For my son, Craig, and I, the dream was not quite the perfect barn find but more of a “field find.” Craig knew that a friend’s grandfather was in possession of a couple of old bikes. All we knew about them was that one was a Norton; the make of the other bike was unknown. The bikes weren’t for sale, as the grandfather was going to restore them someday. It’s a story full of good intentions, one that we’ve all heard before.
We bided our time, and then the day came when the grandfather had to move and the bikes had to be dealt with. I got a call from Craig after he’d gone to look at them: “One’s a Norton and the other is an old Yamaha. They’ve been sitting outside in the open since the Seventies.” Forty or so years. That’s a long time for any bike to be sitting outside.
We agreed on a price, and my son’s friend said he would deliver them both to us. I didn’t know what to expect. At this point I was excited at the thought of restoring a Norton Commando, if we were lucky, and as for the Yamaha, I wasn’t too interested at the time.
A few evenings later, my son and his friend backed the truck into our driveway with our new-found treasures on board. It was dark and difficult to see at first, but as the truck got closer to the light from the open garage I was a bit shocked to see what had arrived. Yes, one was indeed a Norton, but not a Commando; it was a 2-cylinder 400 Electra. The other one was a Yamaha I had never seen before. Now I was interested. I was also shocked to see that both bikes were in horrendous condition — they were worse than I had imagined. Importantly, they were mostly complete, so we knew they could be brought back to life.
Over the next few days we began working on both of the bikes, but as the months passed our attention focused mainly on the Yamaha. We discovered we had come in possession of a numbers-matching 1968 Yamaha YR2C.
In February 1967 Yamaha released their first 350cc 2-stroke twin, the YR1 Grand Prix, then in 1968 it released the YR2 and YR2C, following up with the final versions, the YR3 and YR3C, in 1969. Yamaha advertised the C versions as their scrambler. The road bikes were called the Grand Prix, a name that would certainly catch the interest of many a teenager at the time.
All models came with a double-loop frame with a braced single-tube spine. Chrome fenders and chain guard were the norm throughout the series as well as the spoked 3 x 18-inch front wheel and 3.5 x 18-inch rear wheel. The road bikes came supplied with a ribbed front tire and treaded rear, while the scramblers wore what older riders will remember as “trials universals.”
The differences between the versions were primarily cosmetic. The road bikes had shrouded telescopic forks up front and shrouded rear shocks supporting a rather lengthy swing arm. The scramblers wore rubber gaiters to protect the chrome sliders and open spring shocks adjustable for preload in the rear, all standard fare for manufacturers of the time. Exhaust pipes differed in that the road versions curved downward and stretched to about the rear tire while the scramblers had high pipes with chrome heatshields and a small diameter stinger-type end pipe. The high pipes, though very gracious looking, make the bike very wide, and people a little short in stature will find they make the bike a little uncomfortable.
For 1969 the YR3 mufflers were changed from a slash-type end to a pea-shooter style for the final version. Other differences included taller, braced handlebars and a sump guard for the offroad-type C.
Bringing about 360 pounds of motorcycle to a halt were full width, 7.2-inch diameter drum brakes, with a twin-leading-shoe setup in the front and a single in the rear. Twelve-volt electrics were the norm, with sparks being produced from a twin set of points and dual coils under the tank. Providing the “oomph” to propel these machines along the road is a 2-cylinder, piston-port 2-stroke engine putting out a claimed 36 horsepower at 7,500rpm. Twin 28mm Mikunis supplied the fuel and 2-stroke oil was injected by Yamaha’s Autolube system through four nylon tubes to the base of the cylinders.
The 2-stroke oil is held in a huge 3.4-quart oil tank situated under the seat behind the airbox. Interestingly, the oil tank has a window in the side to monitor the oil level as well as a leather dipstick with embossed graduations to also measure oil level. A similar dipstick is found inside the fuel tank, mounted on a small bracket in the tank under the filler cap.
Bore and stroke remained the same for the entire production at 61mm x 59.6mm and a compression ratio of 7.5:1, according to all the sales brochures. According to Cycle World the ratio changed from 7.5:1 for the YR1 to 6.9:1 for the YR2.
Cylinder porting was changed starting with the YR2, going from three to five ports, a move Yamaha claimed increased scavenging, gave a wider power band, and improved cylinder head cooling.
A multiplate wet clutch handles the power input, transferring it through a 5-speed gearbox having the normal one down, four up configuration through the left side foot pedal. Mention should be made of the clutch design on these bikes, in that it’s not what would be regarded as normal today. Instead of using a long rod through the transmission, pushing on a release at the outer end of the clutch assembly allowing the clutch springs to expand and release the plates, the YR’s release mechanism spins on the outside of the clutch and pushes a circular plate that pushes the plates back in toward the engine. Yamaha didn’t stick with the idea.
Despite its horrible condition, we decided that because it was fairly complete and relatively rare, our 1968 YR2C was worth saving. However, a complete strip-down brought more bad news and thoughts of abandonment: The crankshaft had water damage and needed to be completely rebuilt. The cylinders would have to be bored out to a third and maximum over-size as rust had caused deep pitting in the sleeves; and the generator was very corroded and it looked doubtful it could be saved. Even so, we persevered, doing most of the work ourselves and leaving the most important parts to the experts.
We acquired new-old-stock bearings (NOS), connecting rods and pistons, and sent them off to LA Sleeve Co. in Santa Fe Springs, California, who did a great job rebuilding the crankshaft and boring the cylinders. Third over-size pistons with transfer ports proved difficult to find, so we bought solid pistons and cut the ports in the pistons to match the originals. That’s when we learned how hard pistons are! It took a few hours with drills and files — mixed with a lot of patience — to get the ports the size and shape we needed.
Another surprise for us was the kickstarter. When the bike arrived the kickstarter just dangled. It would engage (though the engine was seized) but wouldn’t return to its normal position. We figured it was probably just a broken spring. Upon stripping the engine down we found the spring to look like new, but when we split the cases we discovered a small steel wedge that was snapped in two. Further examination showed that this wedge resided on a small platform cast into the case and that through much kickstarting the wedge had broken, thus exposing the alloy and allowing it to be chipped away. The wedge, though not the best of designs, is a critical component that limits the rotation of the kickstarter mechanism. Without it functioning properly the kickstarter lever just flops around, displaying the typical symptoms of a broken return spring. The only way to fix the problem is to split the cases. A bit of aluminum welding from an aircraft certified welder and a small bit of machining to flatten the mount had everything back to normal. We thought it would be difficult to obtain a new wedge, but it turns out they are easy to find on the internet from vintage suppliers.
The frame was powder coated semi-gloss black, the spokes were plated and a new rim sourced for the front. We refurbished all we could, polishing and painting as we went. NOS seals and bearings were installed throughout the entire engine and frame, all of them sourced from vendors found after lengthy searches of the internet.
The generator, which was in an awful state, surprisingly worked after giving it a good and delicate cleaning. Hagon shocks were fitted to the rear, and we installed new cables and tires. The rubber knee pads are a bit difficult to find and we ended up having to buy a complete tank with rubbers from eBay just to get one pad to go with the only good one we had. The other was hard and inflexible from exposure to the elements. The seat has also been a bit of a problem to find and currently the bike has one from a YR1. The YR1 seat leaves a bit of a gap between the rear of the tank and the front of the seat, so we’ll keep searching for the correct one.
For the paint, we found a sample of the original blue that hadn’t been exposed to the weather under one of the components. We had it matched by an automotive paint supplier, who provided us with the paint in aerosols, along with an aerosol version of a two-pack clear coat.
Craig did all the final paintwork, making sure the primer coat was well prepared and taking his time spraying the final coats. The bolt-on side panels for the gas tank were painted gloss white. The heat shields and headlight trim should be chrome plated, but for now they are painted black to keep costs down. The final result is certainly far from a concours bike, but it is what I’ve heard judges call an “honest bike.” It’s not perfect, but it is back on the road and it has been given another chance. We’re happy with it.
Press down the choke lever on the inter-connected carbs, reach over to the elongated key in the headlight and give the right side kickstarter a couple of prods and that old 2-stroke melody burbles into life. Care must be taken to first make sure the rear footpeg is folded away or your foot will strike it as you kick the engine over. There’s quite a bit of blue haze until the bike warms up, but then it’s fairly minimal. It takes a strong hand to pull in the clutch, but snicking the gearbox into first is effortless, as well as is changing up through the gears. Under 4,000rpm there’s not much going on, but as the revs start to rise the acceleration becomes quite brisk and there’s that intoxicating 2-stroke howl from the exhaust that makes you want more.
We find that the bike does indeed handle quite well. It doesn’t take a lot of effort to tip it into corners, and it feels quite light and nimble switching from left to right. The brakes are quite good, too, but you have to remind yourself that you’re riding 48-year-old technology.
Since putting a few miles on the bike a couple of problems have surfaced. The carbs have an odd bubbling problem and the clutch actuation seems heavier than it should be, but these are things we are working to solve. Overall, we’re very pleased with the results. Saving these old bikes from the scrap pile always brings us huge satisfaction. Now where did we leave off on the Norton? MC
The latest classic motorcycle events and tours.LEARN MORE