Ajs JS 125-E vs Yamaha YBR 125

The Yamaha YBR 125 passes its MOT first time more often than the Ajs JS 125-E: 71.0% vs 63.2%, a 7.8-point lead.

MOT reliability, side by side

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

Metric	Ajs JS 125-E	Yamaha YBR 125
First-time pass rate	63.2%	71.0%
Outright fail rate	24.6%	17.1%
Vs comparable bikes (age & mileage adjusted)	-8.0 pts	-1.1 pts
Engine size	124cc	124cc
Rank among all models	#5099 of 5428	#4664 of 5428
Median miles at test	12,612	10,652
MOT tests analysed	699	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	Ajs JS 125-E	Yamaha YBR 125
Lights & signalling	14.2%	8.5%
Steering & suspension	8.4%	6.5%
Brakes	8.9%	5.9%
Drive system	8.0%	2.9%
Tyres & wheels	6.3%	4.4%
Structure & body	3.7%	3.8%
Fuel & exhaust	0.7%	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 JS 125-E	Yamaha YBR 125
2011	55.6%	69.1%
2012	64.2%	69.1%
2013	60.0%	69.5%
2014	67.0%	70.0%
2015	59.7%	71.2%
2016	68.6%	71.3%
2017	63.5%	70.7%

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 JS 125-E	Yamaha YBR 125
0k-10k miles	71.4%	76.8%
10k-20k miles	50.9%	67.4%
20k-30k miles	62.9%	63.8%
30k-40k miles	70.5%	62.2%

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

Ajs JS 125-E vs Yamaha YBR 125 FAQ

answers computed from the data above · terms in the glossary

Which is more reliable, the Ajs JS 125-E or the Yamaha YBR 125?

The Yamaha YBR 125 passes its MOT first time more often than the Ajs JS 125-E: 71.0% vs 63.2%, a 7.8-point lead. Adjusted for age, mileage and test class, the Yamaha YBR 125 still comes out ahead: -8.0 points vs comparable bikes for the Ajs JS 125-E, -1.1 for the Yamaha YBR 125. An MOT checks roadworthiness items, not engine or gearbox internals.

What does the Ajs JS 125-E fail its MOT on most?

Lights & signalling: 14.2% of Ajs JS 125-E MOT tests failed on it, then brakes (8.9%).

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 Ajs JS 125-E or the Yamaha YBR 125?

At 30k-40k miles the Ajs JS 125-E passes first time more often: 70.5% for the Ajs JS 125-E vs 62.2% for the Yamaha YBR 125.

AJS JS 125-E 63.2% pass · 699 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.