Ajs Model 31 vs Suzuki GSF600

The Ajs Model 31 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	Ajs Model 31	Suzuki GSF600
First-time pass rate	91.4%	77.3%
Outright fail rate	1.6%	14.2%
Engine size	650cc	599cc
Rank among all models	#588 of 5428	#4013 of 5428
Median miles at test	23,465	21,080
MOT tests analysed	314	143,023
Most common failure	steering and suspension	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.

Pass rate by test year

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

Test year	Ajs Model 31	Suzuki GSF600
2006	90.3%	81.8%
2007	83.9%	80.0%
2008	90.0%	78.4%
2009	93.9%	75.8%
2010	87.5%	75.8%

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	Ajs Model 31	Suzuki GSF600
0k-10k miles	90.8%	86.8%
10k-20k miles	92.7%	80.1%
20k-30k miles	92.1%	75.2%
30k-40k miles	92.3%	71.3%
40k-50k miles	92.6%	69.4%

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

AJS MODEL 31 91.4% pass · 314 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.