BSA D1

125cc Petrol Class 1

#1748 of 5426 overall #58 of 62 BSAs #13 of 734 commuter bikes

87.5%

first-time pass rate

5.4%

failed outright

11,600

median miles at test

391

MOT tests, 2005–2025

Pass rate over time

first-time pass rate by test year · 2006–2012

The D1's first-time pass rate has fallen 2.8 points since 2006, 87.0% to 84.2%.

Pass rate by mileage

how the D1's first-time pass rate falls with the odometer · class average 73.4%

A low-mileage D1 passes first time 92.3% of the time; by 30k that's 84.8%.

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 D1

failure defects by component group · advisories excluded

Component group	Defects	% of defects
lighting and signalling	36	48.6
steering and suspension	13	17.6
tyres and wheels	8	10.8
brakes	8	10.8
drive system	3	4.1
driving controls	2	2.7
suspension	2	2.7
fuel and exhaust	2	2.7

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 D1 beats 4 of its 4 closest rivals (YAMAHA YBR 125, HONDA CG125, HONDA CBF125).

YAMAHA YBR 125 71.0% pass · 125k tests HONDA CG125 72.2% pass · 89.3k tests HONDA CBF125 73.3% pass · 84.4k tests GILERA RUNNER 70.8% pass · 69.9k tests

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 D1.

Pass rate by registration year

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

Best year to buy used: 1952 (85.5% pass). Weakest: 1952 (85.5%).

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.