Ajs Model 18 vs Yamaha FZS600

The Ajs Model 18 passes its MOT first time more often than the Yamaha FZS600: 94.8% vs 82.6%, a 12.2-point lead.

MOT reliability, side by side

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

Metric	Ajs Model 18	Yamaha FZS600
First-time pass rate	94.8%	82.6%
Outright fail rate	0.4%	10.6%
Engine size	500cc	599cc
Rank among all models	#93 of 5428	#3052 of 5428
Median miles at test	7,529	21,612
MOT tests analysed	267	136,558
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.

Pass rate by test year

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

Test year	Ajs Model 18	Yamaha FZS600
2006	97.1%	86.0%
2007	100.0%	84.1%
2008	91.2%	83.4%
2009	97.1%	81.2%
2010	90.9%	82.0%

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 18	Yamaha FZS600
0k-10k miles	96.4%	89.6%
20k-30k miles	93.9%	81.4%

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

AJS MODEL 18 94.8% pass · 267 tests YAMAHA FZS600 82.6% pass · 137k tests

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