Data as of: DVSA MOT results to 2025
Ajs 18S vs Kawasaki ZX-6R
The Ajs 18S passes its MOT first time more often than the Kawasaki ZX-6R: 92.8% vs 78.1%, a 14.7-point lead.
MOT reliability, side by side
| Metric | Ajs 18S | Kawasaki ZX-6R |
|---|---|---|
| First-time pass rate | 92.8% | 78.1% |
| Outright fail rate | 3.0% | 14.0% |
| Engine size | 500cc | 599cc |
| Rank among all models | #330 of 5428 | #3895 of 5428 |
| Median miles at test | 14,829 | 19,446 |
| MOT tests analysed | 598 | 173,956 |
| 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.
What fails, side by side
| Component | Ajs 18S | Kawasaki ZX-6R |
|---|---|---|
| Lights & signalling | 1.8% | 6.1% |
| Steering & suspension | 1.2% | 4.6% |
| Brakes | 0.5% | 5.2% |
| Tyres & wheels | 0% | 3.6% |
| Structure & body | 0.2% | 1.2% |
| Drive system | 0.2% | 1.0% |
| Fuel & exhaust | 0.2% | 0.8% |
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
| Test year | Ajs 18S | Kawasaki ZX-6R |
|---|---|---|
| 2006 | 95.6% | 82.8% |
| 2007 | 97.5% | 81.0% |
| 2008 | 95.8% | 78.4% |
| 2009 | 88.2% | 76.6% |
| 2010 | 88.6% | 76.3% |
| 2011 | 89.6% | 76.6% |
| 2012 | 93.3% | 75.4% |
Each year mixes bikes of different ages, so a fleet that is getting older tends to slip.
Pass rate by mileage
| Mileage | Ajs 18S | Kawasaki ZX-6R |
|---|---|---|
| 0k-10k miles | 93.2% | 86.1% |
| 10k-20k miles | 97.2% | 80.6% |
| 20k-30k miles | 90.5% | 75.4% |
| 30k-40k miles | 88.6% | 71.8% |
| 40k-50k miles | 92.6% | 69.5% |
| 50k-60k miles | 84.4% | 69.0% |
Bands with fewer than 30 tests for either bike are left out.
Ajs 18S vs Kawasaki ZX-6R FAQ
Which is more reliable, the Ajs 18S or the Kawasaki ZX-6R?
The Ajs 18S passes its MOT first time more often than the Kawasaki ZX-6R: 92.8% vs 78.1%, a 14.7-point lead. An MOT checks roadworthiness items, not engine or gearbox internals.
What does the Ajs 18S fail its MOT on most?
Lights & signalling: 1.8% of Ajs 18S MOT tests failed on it, then steering & suspension (1.2%).
What does the Kawasaki ZX-6R fail its MOT on most?
Lights & signalling: 6.1% of Kawasaki ZX-6R MOT tests failed on it, then brakes (5.2%).
Which holds up better at high mileage, the Ajs 18S or the Kawasaki ZX-6R?
At 50k-60k miles the Ajs 18S passes first time more often: 84.4% for the Ajs 18S vs 69.0% for the Kawasaki ZX-6R.
See each bike's full report (trend, mileage curve, failure breakdown and rivals) on its own page.