BIKERELIABILITY Reg check
League table/ AJS/JSM 125
Model report · 2005–2025

AJS JSM 125

124cc Petrol Class 1
54.9%
first-time pass rate
35.4%
failed outright
9,376
median miles at test
164
MOT tests, 2005–2025
-18.0pp
vs expected · age & mileage

The pass rate is the MOT first-time pass: a roadworthiness check of the items an MOT covers (brakes, lights, tyres, steering, structure, emissions), not a full mechanical inspection of engine or gearbox internals. It is a reliability signal, not a complete measure of mechanical reliability. What this measures.

“vs expected” adjusts for age, mileage and test class, so a cherished classic and a hard-used commuter are compared fairly. How this works.

What fails on a JSM 125

failure defects by component group · advisories excluded
Component group Share of defects Defects % of defects
lighting and signalling
74 29.4
brakes
69 27.4
steering and suspension
52 20.6
lamps and reflectors
16 6.3
drive system
16 6.3
fuel and exhaust
8 3.2
tyres and wheels
7 2.8
body and structure
5 2
structure and attachments
3 1.2
driving controls
2 0.8

Defects recorded against failed normal tests, 2005–2025, grouped by DVSA inspection section. One test can record multiple defects.

How rivals compare

same type, similar capacity, high test volume

On first-time pass rate the JSM 125 beats 0 of its 4 closest rivals (YAMAHA YBR 125, HONDA CG125, HONDA CBF125).

Rivals share this bike's type and sit within ±30% of its engine capacity, ≥ 5,000 tests. Card colour = better/worse first-time pass rate than the JSM 125.

Compare with any bike

rival not listed above? pick any model to see it head-to-head with the JSM 125

Pass rate by registration year

how each model-year cohort fares · registration year from first use date

Best year to buy used: 2010 (56.9% pass). Weakest: 2010 (56.9%).

First-time pass rate by the year each bike was first registered (cohorts with ≥ 50 tests). Older cohorts are survivors: the worst examples have already left the road, which tends to lift the earliest years.

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