Bsa M20 vs Suzuki GSF600

The Bsa M20 passes its MOT first time more often than the Suzuki GSF600: 91.4% vs 77.3%, a 14.1-point lead.

MOT reliability, side by side

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

Metric	Bsa M20	Suzuki GSF600
First-time pass rate	91.4%	77.3%
Outright fail rate	2.5%	14.2%
Engine size	500cc	599cc
Rank among all models	#588 of 5428	#4013 of 5428
Median miles at test	7,746	21,080
MOT tests analysed	1,295	143,023
Most common failure	lighting and signalling	brakes

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.

What fails, side by side

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

Component	Bsa M20	Suzuki GSF600
Lights & signalling	1.1%	6.7%
Brakes	1.1%	6.1%
Steering & suspension	0.9%	3.6%
Tyres & wheels	0.4%	3.3%
Fuel & exhaust	0.4%	1.2%
Structure & body	0.1%	1.5%
Drive system	0%	1.4%

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 M20	Suzuki GSF600
2008	90.2%	78.4%
2009	87.3%	75.8%
2010	92.1%	75.8%
2011	91.8%	76.1%
2012	84.8%	75.9%
2013	91.9%	74.7%
2014	88.6%	75.0%
2015	94.4%	75.5%

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 M20	Suzuki GSF600
0k-10k miles	90.9%	86.8%
10k-20k miles	94.1%	80.1%
20k-30k miles	92.8%	75.2%
30k-40k miles	80.9%	71.3%
40k-50k miles	92.8%	69.4%

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

Bsa M20 vs Suzuki GSF600 FAQ

answers computed from the data above · terms in the glossary

Which is more reliable, the Bsa M20 or the Suzuki GSF600?

The Bsa M20 passes its MOT first time more often than the Suzuki GSF600: 91.4% vs 77.3%, a 14.1-point lead. An MOT checks roadworthiness items, not engine or gearbox internals.

What does the Bsa M20 fail its MOT on most?

Lights & signalling: 1.1% of Bsa M20 MOT tests failed on it, then brakes (1.1%).

What does the Suzuki GSF600 fail its MOT on most?

Lights & signalling: 6.7% of Suzuki GSF600 MOT tests failed on it, then brakes (6.1%).

Which holds up better at high mileage, the Bsa M20 or the Suzuki GSF600?

At 40k-50k miles the Bsa M20 passes first time more often: 92.8% for the Bsa M20 vs 69.4% for the Suzuki GSF600.

BSA M20 91.4% pass · 1,295 tests SUZUKI GSF600 77.3% pass · 143k tests

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