Two-Stroke Triple Tracker from Moore’s Competition Cycles…
During the 1970s, the Suzuki GT series of three-cylinder two-stroke street bikes never earned quite the same widow-making reputation as the infamously fast and lethal Kawasaki triples…mainly because the Suzukis were designed as more well-rounded machines.
“Back in 1972 Suzuki had a new idea: Take the latest in superbike technology. Scale it down here, beef it up there, and you’d have a pleasant combination of touring, sport, and commuting, all for an attractive price.” –Cycle World, 1976
The GT380 was designed for the hotly contested 300-400cc market. It featured the Ram Air system Suzuki had developed for its road racers, a six-speed transmission, and a front disc brake on all but the earliest models. The 371cc engine was rated at 38 horsepower and 28 lb-ft of torque, with porting, timing, and compression geared toward longevity and smooth power delivery rather than peak horsepower.
Enter our friend Jesse Moore of Moore’s Competition Cycles, a self-proclaimed flat track addict who grew up racing motocross and hanging out in the workshop of his father, an engine-builder who works on 60s Grand Prix cars. Back in 2019, Jesse found his way to flat track through DirtQuake and hasn’t looked back.
When it came time to build a flat tracker for his dad to race in the UK’s DTRA (Dirt Track Riders Association) rounds, they picked up a GT380 donor…not realizing quite how trashed it was:
“When the frame came back from the blasters, it was clear just how nasty it was…the welding had been done by the back of a pigeon, and the whole bike just looked wrong when we assembled it.”
While many builders might have abandoned the project at that point, the Moores doubled down. They decided to put their fabrication prowess to good use, building their own frame out of T45 tubing. Says Jesse:
“It would be based off of a good friend’s ‘Shell Thuet’ flat track frame, which I measured and drew, and then modified slightly to house the big Suzuki engine.”
The geometry, wheelbase, and center of gravity are now much better suited to the track, while the engine has been rebuilt with X7 pistons, labyrinth seals, and a Zeeltronic programmable ignition. The oil pump was ditched to run premix, the generator eliminated in favor of a total-loss system, and the Moore boys built the exhaust out of 100 separate sections.
Chris Pugh (@shed_days) handled the paint, so this smoker looks as good as it goes, and the Moores have been very happy with the bike both on and off the track:
“It’s fast, it handles beautifully, and it’s really cool to see how people react to something we really just made for a bit of a laugh. We are producing our frames, pipes, and other components now to sell, and I like to think that this is a bit of a showcase of what we can do.”
Below, Jesse Moore (@jessemoore72) gives us the full story on this triple-cylinder two-stroke tracker.
Suzuki GT380 Tracker: In the Builder’s Words…
We wanted to build a three-cylinder two-stroke flat tracker so that we had something different that would sound good and turn heads, and also give Dad something to ride at the DTRA rounds here in the UK. We set about trying to find a donor bike, but Kawasaki triples have all shot up in value in the last few years, and finding one was going to be impossible with our initial budget, so Dad found a Suzuki GT380 — and a really nasty one at that!
We laced up a set of 19 x 2.5″ rims onto the Suzuki hubs, mounted some Maxxis flat track tyres, found a decent set of forks and yokes, and sent the frame off for blasting to see what we were working with, starting to balance it all together. When the frame came back from the blasters, it was clear just how nasty it was…the welding had been done by the back of a pigeon, and the whole bike just looked wrong when we assembled it. It just looked like a 70s street bike with big fat tyres on it.
After thinking about it for a bit, we decided to make a frame. It would be based off of a good friend’s “Shell Thuet” flat track frame, which I measured and drew, and then modified slightly to house the big Suzuki engine.
By building our own frame, we managed to solve a lot of our initial problems, for example:
The headstock is now set at the correct angle to get it to turn in, but it’s also four inches higher than it was on the stock frame, effectively dropping the engine four inches and of course the centre of gravity.
The wheelbase is short, allowing far better traction out of the bends, and more agility into the turns.
The seat height is low, keeping you closer to the ground and making the bike feel really planted.
The frame is really light; it’s made of thin-wall t45 tubing, and with the swingarm it weighs just 8 kilograms, some 15 kilos less than the stock frame.
We also tipped the engine forward, again to get the centre of gravity lower, but also to lift the sprocket and allow us to raise the swingarm pivot point, putting some angle into the swingarm and again improving hook up. This bike really drives out of the corner, not what you’d expect from a three-cylinder two-stroke!
The engine is pretty standard really. We used Suzuki X7 pistons to give a little more inlet duration, moved the crank bearings, and used labyrinth seals to seal between the crankcase sections, and redrilled the oil ways to allow us to throw the oil pump assembly in the bin and run premix.
It also uses a fully mappable Zeeltronic ignition system. Using the ignition system meant we could run it total loss, so didn’t need to use the generator in the engine, so that was another heavy lump we got to throw away. We went ahead and cut the side cover down too, as it no longer needed to be so wide, a little flat aluminium cover would do, and that would help narrow the already very wide engine — it saved a bit more weight too
The same treatment was given to the whole engine; anything that we didn’t need was cut down or removed. Other than that, it’s standard. We’ve got a few plans to improve it: I think we will raise the cylinder at the base gasket and correct the squish by decking the top of the cylinder, that will improve the port timing and get it to go a little better, although it sings at 11,000 rpm already, so maybe it’ll do for now.
The pipes were our next challenge; there are over 100 pieces in them and they were designed, rolled, routed, and welded by us to suit the bike and what we wanted from it.
They’ve really woken up the bike and they really sound great, and let’s face it, that’s the main thing with a three-cylinder smoker.
Our mate Chris Pugh (@shed_days) painted it for us in classic Suzuki colours. We gave him free rein to do it how he thought it should be, and I think you’ll agree, he did a really nice job.
The bike has gone down really well everywhere we’ve taken it. It’s fast, it handles beautifully, and it’s really cool to see how people react to something we really just made for a bit of a laugh.
We are producing our frames, pipes, and other components now to sell, and I like to think that this is a bit of a showcase of what we can do. We can design and build anything you like within reason, and I think this bike shows that.