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.
Pass rate by mileage
A low-mileage D14/4 passes first time 92.1% of the time; by 30k that's 85.7%.
First-time pass rate by odometer reading at test, 10,000-mile bands for this model. Mileage is the strongest reliability signal. See the full curve.
What fails on a D14/4
| Component group | Share of defects | Defects | % of defects |
|---|---|---|---|
| lighting and signalling |
|
7 | 35 |
| tyres and wheels |
|
5 | 25 |
| brakes |
|
4 | 20 |
| steering and suspension |
|
3 | 15 |
| Items Not Tested |
|
1 | 5 |
Defects recorded against failed normal tests, 2005–2025, grouped by DVSA inspection section. One test can record multiple defects.
How rivals compare
On first-time pass rate the D14/4 beats 0 of its 1 closest rivals (BSA BANTAM).
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 D14/4.
Compare with any bike
More BSA models
Pass rate by registration year
Best year to buy used: 1968 (86.1% pass). Weakest: 1968 (86.1%).
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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Free to embed on your site, blog or forum — a live Bsa D14/4 reliability card that stays up to date and links back here. More on the free API page.