2019 KTM 125 Duke 19 0.1L Petrol · LL68 YMU

The defining mechanical concern for this 2019 KTM 125 Duke is the cluster of four major defects recorded at the most recent MOT on 2 July 2025, which resulted in a failure. The rear brake was found to be excessively binding, the drive chain was worn beyond service limits, the rear sprocket was excessively loose, and a rear reflector was missing. The prior three tests (2022, 2023, and 2024) all returned clean passes with no advisories or failures recorded, so there is a clear and abrupt deterioration between January 2024 and July 2025. The combination of brake, chain, and sprocket issues is mechanically coherent: a binding rear caliper or stuck piston can lead to overheating, premature pad and disc wear, and excessive drag that loads the drivetrain, while prolonged neglect of chain adjustment and lubrication accelerates both chain stretch and sprocket wear. The missing reflector is a minor compliance issue in isolation but, together with the drivetrain and brake items, suggests the machine was not presented for test in a roadworthy state and raises questions about routine maintenance in the period leading up to the 2025 test. With 5,866 miles recorded over approximately seven years, this Duke is being used at a very low rate of around 838 miles per year, a figure consistent with short seasonal riding, occasional weekend use, or significant periods of standing. The MOT cadence is annual from 2022 to 2025, indicating the machine has been kept on the road throughout that window rather than being declared SORN for extended periods, but the low annual mileage means much of its life is spent static. Mechanically, this is relevant on a 125 Duke because standing allows moisture to condense inside the fuel tank, carburettor (if not deleted for later models), and exhaust, accelerates corrosion on the chain and exposed fasteners, dries out rubber components such as fork seals, swingarm pivot bushes, and brake caliper pistons, and leads to brake disc corrosion and pad bonding to the caliper. The binding rear brake and loose rear sprocket recorded in 2025 are exactly the type of deterioration one would expect to see where a light-use machine has been left standing between short rides, particularly over winter months when road salt is prevalent. A prospective buyer should focus inspection effort on the exact subsystems flagged in the 2025 failure. The rear brake should be checked by spinning the wheel with the machine on a stand to confirm it rotates freely with no roughness, and the caliper should be inspected for seized pistons, perished guide pins, and cracked or perished dust seals. The disc should be examined for a pronounced lip, blueing from heat, or heavy surface corrosion, and the rear master cylinder and brake hose checked for hardened rubber or weeping fluid. On the test ride, any rear brake drag should be felt as resistance to free rolling, pulling to one side under braking, or a hot rear caliper immediately after a short stop. The drive chain and sprockets should be inspected with the chain tensioned correctly; look for tight spots where the chain binds rather than flexing smoothly, visibly stretched links that sit partway off the rear sprocket, and hooked or pointed sprocket teeth. The chain adjusters should be checked for equal markings on both sides, indicating the rear wheel is in alignment, and the chain guard and slider examined for wear. Beyond the flagged items, the 2025 failure warrants a broader check of areas commonly affected on low-mileage KTM Dukes. The front brake and its caliper should be given the same level of scrutiny as the rear, as seized front caliper pistons are a known issue on lightly used machines. The fork stanchions should be inspected under the dust seals for any pitting, corrosion rings, or oil staining, and the fork action checked for smoothness with the front brake applied over a series of compressions. The throttle body and idle quality should be assessed, as low mileage combined with fuel containing ethanol can lead to varnish deposits and rough running when the machine eventually returns to regular use. The tyres should be examined for age-related sidewall cracking as well as tread depth, given that a seven-year-old motorcycle on original or near-original rubber may have hardened compound and perished sidewalls even if the tread appears legal. Finally, electrical items, indicators, headlight, horn, and number plate light should all be confirmed operational, as the missing reflector on the 2025 test may indicate other minor compliance items have been overlooked, and the machine should be ridden far enough to bring it fully up to operating temperature so that any binding brakes, transmission neutrals, or fuelling issues can be felt before any commitment is made.