MZ 125SM vs Yamaha YBR 125

The Yamaha YBR 125 passes its MOT first time more often than the MZ 125SM: 71.0% vs 65.5%, a 5.5-point lead.

MOT reliability, side by side

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

Metric	MZ 125SM	Yamaha YBR 125
First-time pass rate	65.5%	71.0%
Outright fail rate	24.3%	17.1%
Vs comparable bikes (age & mileage adjusted)	-5.1 pts	-1.1 pts
Engine size	124cc	124cc
Rank among all models	#4992 of 5428	#4664 of 5428
Median miles at test	17,087	10,652
MOT tests analysed	692	124,897
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.

What fails, side by side

share of each bike's MOT tests that failed on the component · lower is better

Component	MZ 125SM	Yamaha YBR 125
Lights & signalling	15.6%	8.5%
Brakes	10.4%	5.9%
Steering & suspension	7.5%	6.5%
Tyres & wheels	5.6%	4.4%
Drive system	4.8%	2.9%
Structure & body	1.7%	3.8%
Fuel & exhaust	0.6%	0.6%

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

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

Test year	MZ 125SM	Yamaha YBR 125
2008	67.6%	71.1%
2009	64.1%	70.7%
2010	61.3%	71.4%
2011	63.0%	69.1%
2012	72.9%	69.1%
2013	71.1%	69.5%
2014	51.1%	70.0%
2015	55.9%	71.2%

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	MZ 125SM	Yamaha YBR 125
0k-10k miles	63.9%	76.8%
10k-20k miles	65.1%	67.4%
20k-30k miles	63.6%	63.8%
30k-40k miles	75.0%	62.2%
40k-50k miles	73.0%	63.4%

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

MZ 125SM vs Yamaha YBR 125 FAQ

answers computed from the data above · terms in the glossary

Which is more reliable, the MZ 125SM or the Yamaha YBR 125?

The Yamaha YBR 125 passes its MOT first time more often than the MZ 125SM: 71.0% vs 65.5%, a 5.5-point lead. Adjusted for age, mileage and test class, the Yamaha YBR 125 still comes out ahead: -5.1 points vs comparable bikes for the MZ 125SM, -1.1 for the Yamaha YBR 125. An MOT checks roadworthiness items, not engine or gearbox internals.

What does the MZ 125SM fail its MOT on most?

Lights & signalling: 15.6% of MZ 125SM MOT tests failed on it, then brakes (10.4%).

What does the Yamaha YBR 125 fail its MOT on most?

Lights & signalling: 8.5% of Yamaha YBR 125 MOT tests failed on it, then steering & suspension (6.5%).

Which holds up better at high mileage, the MZ 125SM or the Yamaha YBR 125?

At 40k-50k miles the MZ 125SM passes first time more often: 73.0% for the MZ 125SM vs 63.4% for the Yamaha YBR 125.

MZ 125SM 65.5% pass · 692 tests YAMAHA YBR 125 71.0% pass · 125k tests

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