Ajs DD vs Yamaha YBR 125

The Yamaha YBR 125 passes its MOT first time more often than the Ajs DD: 71.0% vs 68.4%, a 2.6-point lead.

MOT reliability, side by side

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

Metric	Ajs DD	Yamaha YBR 125
First-time pass rate	68.4%	71.0%
Outright fail rate	20.5%	17.1%
Vs comparable bikes (age & mileage adjusted)	-9.3 pts	-1.1 pts
Engine size	125cc	124cc
Rank among all models	#4831 of 5428	#4664 of 5428
Median miles at test	3,780	10,652
MOT tests analysed	1,798	124,897
Most common failure	lamps and reflectors	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	Ajs DD	Yamaha YBR 125
Lights & signalling	13.4%	8.5%
Steering & suspension	7.4%	6.5%
Brakes	6.2%	5.9%
Structure & body	6.3%	3.8%
Tyres & wheels	3.9%	4.4%
Drive system	1.2%	2.9%
Fuel & exhaust	0.4%	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	Ajs DD	Yamaha YBR 125
2018	67.8%	72.0%
2019	68.4%	71.8%
2020	69.5%	73.4%
2021	65.4%	71.6%
2022	69.1%	71.3%
2023	64.6%	71.1%
2024	73.1%	70.9%
2025	69.1%	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	Ajs DD	Yamaha YBR 125
0k-10k miles	68.6%	76.8%
10k-20k miles	62.0%	67.4%

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

Ajs DD vs Yamaha YBR 125 FAQ

answers computed from the data above · terms in the glossary

Which is more reliable, the Ajs DD or the Yamaha YBR 125?

The Yamaha YBR 125 passes its MOT first time more often than the Ajs DD: 71.0% vs 68.4%, a 2.6-point lead. Adjusted for age, mileage and test class, the Yamaha YBR 125 still comes out ahead: -9.3 points vs comparable bikes for the Ajs DD, -1.1 for the Yamaha YBR 125. An MOT checks roadworthiness items, not engine or gearbox internals.

What does the Ajs DD fail its MOT on most?

Lights & signalling: 13.4% of Ajs DD MOT tests failed on it, then steering & suspension (7.4%).

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%).

AJS DD 68.4% pass · 1,798 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.