Why this vehicle matters
The Bonneville defined what a motorcycle should look like for two decades. Launched in 1959 after Johnny Allen set speed records at the Bonneville Salt Flats, the T120 became the template for the cafe racer movement. Steve McQueen rode one. Countless movies featured them. The parallel twin has a character that inline fours can't match — a mechanical heartbeat that resonates at every RPM. This is the motorcycle that British motorcycling's reputation was built on.
Patina notes
The Bonneville ages like fine whiskey. The paint develops depth. The chrome pits in interesting patterns. Oil leaks mark their territory (British bikes leak; accept it). Mine has decades of honest use showing. Over-restoration ruins these bikes — they should look like motorcycles that have been ridden, not museum pieces. The patina tells the story of every rider before you.
Ownership reality
Lucas electrics are the famous weak point — 'prince of darkness' jokes are earned. Points need regular attention. Oil leaks are constant companions. But the engine is mechanically simple and well-understood. A rebuilt Bonneville with modern electronic ignition and reliable electrics can be a genuine rider. The parts network is extensive. Just budget for the maintenance relationship you're signing up for.
The verdict
Buy if
You want to understand why British bikes created a cult. You're willing to maintain a relationship with your motorcycle. You appreciate mechanical character over clinical perfection.
Skip if
You need turn-key reliability. You're not comfortable with points ignition and carb tuning. Oil on your garage floor bothers you.
What to look for
- → Engine case cracks (look carefully around mounts)
- → Gearbox condition (2nd gear often weak)
- → Primary chain adjuster wear
- → Frame cracks at steering head
- → Wiring harness condition
- → Matching numbers documentation
Common problems
- ⚠ Lucas electrical failures (expected)
- ⚠ Oil leaks from everywhere
- ⚠ Primary chain stretch
- ⚠ Clutch adjustment constant
- ⚠ Points wear and timing drift
- ⚠ Vibration loosens everything
Parts & community
Parts sources
- Lowbrow Customs
- British Cycle Supply
- Triumph Only
- eBay UK (good source)
- Vintage Triumph Register members
Forums & communities
- TriumphRat.net
- BritBike Forum
- British Iron Forum
- Vintage Triumph Register
Sources
- Personal ownership · 2026-02-02
Specifications
| Engine | 649cc air-cooled parallel twin (OHV) |
| Power | 46 hp @ 6,500 rpm |
| Torque | 37 lb-ft @ 6,000 rpm |
| Transmission | 4-speed |
| Drivetrain | Chain |
| Weight | 410 lbs wet |
| Wheelbase | 55.5 inches |
| Production | Named after 1956 Bonneville Salt Flats speed record |
Notable Features
- • Parallel twin vibration character
- • Points ignition
- • Kickstart primary, optional electric
- • Available in unit or pre-unit construction
About Triumph
British sports car heritage spanning cars and motorcycles. Triumph built some of the most characterful machines to ever drip oil on a garage floor.
View all Triumph vehicles →Find one
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