BIKERELIABILITY
MOT DATA · GREAT BRITAIN · 2005–2025
League table/ BSA/B25
Model report · 2005–2025

BSA B25

250cc Petrol Class 2
#1448 of 5426 overall #55 of 62 BSAs #881 of 2787 other bikes
88.5%
first-time pass rate
4.1%
failed outright
9,304
median miles at test
886
MOT tests, 2005–2025

Pass rate over time

first-time pass rate by test year · 2006–2017

The B25's first-time pass rate has fallen 4.3 points since 2006, 91.1% to 86.8%.

78%89%100%2006: 91.1% pass (79 tests)2007: 91.5% pass (71 tests)2008: 88.9% pass (63 tests)2009: 86.7% pass (60 tests)2010: 96.6% pass (59 tests)2011: 81.8% pass (66 tests)2012: 85.9% pass (71 tests)2013: 87.2% pass (78 tests)2014: 91.0% pass (78 tests)2015: 89.7% pass (78 tests)2016: 85.1% pass (67 tests)2017: 86.8% pass (68 tests)20062017

Pass rate by mileage

how the B25's first-time pass rate falls with the odometer · class average 84.9%

A low-mileage B25 passes first time 88.3% of the time; by 30k that's 90.6%.

86%89%92%0k: 88.3% pass (429 tests)10k: 86.7% pass (210 tests)20k: 91.2% pass (137 tests)30k: 90.6% pass (32 tests)0k20k30k

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 B25

failure defects by component group · advisories excluded
Component group Share of defects Defects % of defects vs all bikes
lighting and signalling
30 40.5 0.5×
steering and suspension
22 29.7 0.6×
brakes
8 10.8 0.2×
body and structure
3 4.1 0.7×
drive system
3 4.1 0.3×
fuel and exhaust
2 2.7 0.3×
tyres
2 2.7 0.2×
tyres and wheels
2 2.7 0.1×
driving controls
1 1.4 0.5×
structure and attachments
1 1.4 0.2×

Defects recorded against failed normal tests, 2005–2025, grouped by DVSA inspection section. One test can record multiple defects. "vs all bikes" is how often this model's tests record a defect in the group, as a multiple of the all-bike rate.

How rivals compare

same type, similar capacity, high test volume

On first-time pass rate the B25 beats 4 of its 4 closest rivals (YAMAHA YP250, YAMAHA WR250F, HONDA XR250).

YAMAHA YP250 82.5% pass · 12.4k tests YAMAHA WR250F 78.0% pass · 10.5k tests HONDA XR250 78.8% pass · 9,277 tests HONDA CBF250 84.9% pass · 7,536 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 B25.

Pass rate by registration year

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

Best year to buy used: 1970 (89.6% pass). Weakest: 1968 (87.9%).

87%89%90%1968: 87.9% pass (198 tests)1969: 88.5% pass (200 tests)1970: 89.6% pass (182 tests)1971: 89.2% pass (232 tests)196819701971

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.

BSA B25 FAQ

answers computed from the data above · terms in the glossary

Is the BSA B25 reliable?

The BSA B25 is more reliable than average for its class: 88.5% of its 886 MOT tests (2005–2025) passed first time, against a class average of 84.9%. That ranks it #1448 of 5426 models.

What does a B25 fail its MOT on most?

lighting and signalling — 41% of all defects recorded against failed B25 tests.

What is the best year of B25 to buy used?

By first-time pass rate, 1970-registered examples do best (89.6%) and 1968 worst (87.9%). Condition and history still trump the year.

How many miles will a B25 last?

The median B25 shows 9,304 miles at test, and examples around 30k miles still pass 90.6% of the time — mileage alone rarely kills one.