Norton Mercury vs Yamaha FZS600

The Norton Mercury passes its MOT first time more often than the Yamaha FZS600: 89.2% vs 82.6%, a 6.6-point lead.

MOT reliability, side by side

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

Metric	Norton Mercury	Yamaha FZS600
First-time pass rate	89.2%	82.6%
Outright fail rate	3.4%	10.6%
Engine size	650cc	599cc
Rank among all models	#1212 of 5428	#3052 of 5428
Median miles at test	11,345	21,612
MOT tests analysed	204	136,558
Most common failure	tyres and wheels	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 mileage

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

Mileage	Norton Mercury	Yamaha FZS600
0k-10k miles	90.1%	89.6%
10k-20k miles	92.9%	85.5%

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

NORTON MERCURY 89.2% pass · 204 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.