1981 Suzuki TS125: A sympathetic restoration.
Mechanical assessment, preservation and careful restoration of an original two-stroke trail bike.
Bought in February 2026, this 1981 Suzuki TS125 was a remarkably complete and original motorcycle with around 3,000 miles, its original toolkit and even a spare fuse still present. Where the CG125 became an exercise in reinterpretation, the TS has become an exercise in restraint: learning what to preserve, what to restore and what should be left alone.
Starting Point
The TS125 arrived as a rare kind of project: aged, but largely unspoilt. Its originality was not something to be stripped away in pursuit of a new idea; it was the reason the motorcycle deserved careful attention in the first place.
The work in context
This project has made me more deliberate in how I approach restoration. The work is less about imposing a design direction and more about listening to the motorcycle: measuring wear, diagnosing faults and making the smallest necessary intervention.
It has also strengthened the habits I developed through the CG125 and through workshop experience: work methodically, use the right measuring equipment, consult the manual, and do not substitute confidence for evidence.
Fuel and ignition
The original carburettor was ultrasonically cleaned and rebuilt with fresh service components. I decided on buyuing a fresh OEM needle as the original showed significant wear marks / scoring.
As with the CG125, the carburettor work has been a reminder that the small, methodical jobs are often what make a motorcycle satisfying to own. A clean and correctly assembled fuel system does not announce itself, but it determines how the machine starts, responds and behaves on the road.
The spark plug cap was replaced with an NGK equivalent, as the original was crumbling. With each change I was getting the bike back to a mechanical baseline before truly assessing its condition.
Rebuilding the rear-end
The rear of the motorcycle was fully refurbished as one considered assembly.
The swingarm, brake components and side stand were Cerakoted, then rebuilt with a new swingarm bearing and fresh sprockets. This was not simply cosmetic work; it was an opportunity to restore the function and finish of parts that receive constant use and exposure.
Working through the assembly made the relationship between the chassis, drivetrain and braking system much clearer. The goal was to leave it cleaner, more dependable and mechanically sound without making it feel over-restored.
Assessing the engine, restoring the mechanical baseline
Before committing to a rebuild, I wanted a clear picture of the engine’s condition.
Ignition timing was set using a dial gauge and cigarette paper. I also made bungs for a crankcase leak-down test, pressurising the two-stroke crankcase to 5 psi to check the integrity of the seals and joints.
The piston-to-cylinder clearance was then measured using an outside micrometer and dial bore gauge. The result placed it only 0.01 mm from the service limit: close enough that a proper rebore and top-end rebuild became the right decision rather than a speculative one.
The process reinforced the importance of measurement. The answer was not to replace parts because they looked old, but to understand whether they had reached the end of their useful life.
The top end rebuild
The cylinder is now being rebored and the top end rebuilt with a fresh piston, rings, small-end bearing and circlips.
This stage is still in progress, but it represents the central mechanical purpose of the restoration: returning the engine to a sound, known condition while retaining as much of the original motorcycle as possible.
Current form
The TS125 remains an evolving restoration. It is not being rushed towards a finish line, because the value of the project lies as much in the process as the result.
It has become a practical study in two-stroke diagnosis, precision measurement and sympathetic preservation. More than that, it is teaching me that quality sometimes means doing less: keeping what is good, repairing what is necessary and allowing the history of the machine to remain visible. Although saying that, come wintertime I'm sure I will get the urge to do a full nut and bolt restoration.
