Bsa B31 vs Yamaha RD350

The Bsa B31 passes its MOT first time more often than the Yamaha RD350: 92.0% vs 86.3%, a 5.7-point lead.

MOT reliability, side by side

first-time pass rate, outright fail rate and tests analysed · 2005–2025

Metric	Bsa B31	Yamaha RD350
First-time pass rate	92.0%	86.3%
Outright fail rate	3.1%	6.6%
Vs comparable bikes (age & mileage adjusted)	+12.2 pts	+2.4 pts
Engine size	350cc	347cc
Rank among all models	#470 of 5428	#2120 of 5428
Median miles at test	15,803	23,256
MOT tests analysed	3,429	19,574
Most common failure	lighting and signalling	lighting and signalling

First-time outcomes on normal tests, 2005–2025. "Most common failure" is the component group with the most recorded defects on failed tests. Read pass rates against test counts: a smaller sample is noisier. Source: DVSA anonymised MOT results.

"Vs comparable bikes" is the first-time pass rate minus the rate expected for each bike's own mix of age, mileage and test class, in percentage points: positive means better than comparable bikes. How this works.

What fails, side by side

share of each bike's MOT tests that failed on the component · lower is better

Component	Bsa B31	Yamaha RD350
Lights & signalling	1.3%	3.2%
Brakes	1.3%	2.7%
Steering & suspension	1.1%	2.5%
Tyres & wheels	0.6%	0.9%
Drive system	0.3%	0.5%
Fuel & exhaust	0.2%	0.4%
Structure & body	0.1%	0.4%

A test that fails on two components counts once in each. Component links go to the bikes most likely to fail on it.

Pass rate by test year

first-time MOT pass rate in each calendar year both bikes were tested

Test year	Bsa B31	Yamaha RD350
2009	92.4%	80.6%
2010	91.9%	81.9%
2011	89.8%	82.2%
2012	92.6%	84.7%
2013	83.1%	85.8%
2014	87.5%	86.6%
2015	100.0%	85.3%
2016	87.5%	88.8%

Each year mixes bikes of different ages, so a fleet that is getting older tends to slip.

Pass rate by mileage

first-time MOT pass rate by miles on the clock at test

Mileage	Bsa B31	Yamaha RD350
0k-10k miles	91.6%	88.9%
10k-20k miles	92.8%	87.5%
20k-30k miles	92.0%	85.5%
30k-40k miles	91.9%	85.3%
40k-50k miles	90.3%	83.7%
50k-60k miles	93.0%	83.0%

Bands with fewer than 30 tests for either bike are left out.

Bsa B31 vs Yamaha RD350 FAQ

answers computed from the data above · terms in the glossary

Which is more reliable, the Bsa B31 or the Yamaha RD350?

The Bsa B31 passes its MOT first time more often than the Yamaha RD350: 92.0% vs 86.3%, a 5.7-point lead. Adjusted for age, mileage and test class, the Bsa B31 still comes out ahead: +12.2 points vs comparable bikes for the Bsa B31, +2.4 for the Yamaha RD350. An MOT checks roadworthiness items, not engine or gearbox internals.

What does the Bsa B31 fail its MOT on most?

Lights & signalling: 1.3% of Bsa B31 MOT tests failed on it, then brakes (1.3%).

What does the Yamaha RD350 fail its MOT on most?

Lights & signalling: 3.2% of Yamaha RD350 MOT tests failed on it, then brakes (2.7%).

Which holds up better at high mileage, the Bsa B31 or the Yamaha RD350?

At 50k-60k miles the Bsa B31 passes first time more often: 93.0% for the Bsa B31 vs 83.0% for the Yamaha RD350.

BSA B31 92.0% pass · 3,429 tests YAMAHA RD350 86.3% pass · 19.6k tests

See each bike's full report (trend, mileage curve, failure breakdown and rivals) on its own page.