Moto Guzzi 850 T4 vs Yamaha FZS600

The Moto Guzzi 850 T4 passes its MOT first time more often than the Yamaha FZS600: 86.2% vs 82.6%, a 3.6-point lead.

MOT reliability, side by side

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

Metric	Moto Guzzi 850 T4	Yamaha FZS600
First-time pass rate	86.2%	82.6%
Outright fail rate	7.2%	10.6%
Vs comparable bikes (age & mileage adjusted)	+2.8 pts	-0.8 pts
Engine size	844cc	599cc
Rank among all models	#2148 of 5428	#3052 of 5428
Median miles at test	50,366	21,612
MOT tests analysed	487	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.

"Vs comparable bikes" is the first-time pass rate minus the rate expected for each bike's own mix of age, mileage and test class, in percentage points: positive means better than comparable bikes. How this works.

Pass rate by test year

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

Test year	Moto Guzzi 850 T4	Yamaha FZS600
2008	83.3%	83.4%
2009	82.4%	81.2%
2010	76.5%	82.0%
2011	84.8%	81.1%
2012	85.7%	80.2%
2014	87.1%	81.2%
2016	93.5%	82.2%
2017	87.5%	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	Moto Guzzi 850 T4	Yamaha FZS600
0k-10k miles	86.5%	89.6%
10k-20k miles	88.9%	85.5%
20k-30k miles	94.2%	81.4%
40k-50k miles	92.0%	76.8%
50k-60k miles	78.3%	74.7%

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

MOTO GUZZI 850 T4 86.2% pass · 487 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.