Royal Enfield Bullet Efi E4 vs Yamaha FZS600

The Royal Enfield Bullet Efi E4 passes its MOT first time more often than the Yamaha FZS600: 89.6% vs 82.6%, a 7.0-point lead.

MOT reliability, side by side

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

Metric	Royal Enfield Bullet Efi E4	Yamaha FZS600
First-time pass rate	89.6%	82.6%
Outright fail rate	4.8%	10.6%
Vs comparable bikes (age & mileage adjusted)	-0.1 pts	-0.8 pts
Engine size	499cc	599cc
Rank among all models	#1077 of 5428	#3052 of 5428
Median miles at test	4,013	21,612
MOT tests analysed	897	136,558
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	Royal Enfield Bullet Efi E4	Yamaha FZS600
Brakes	1.4%	4.5%
Lights & signalling	2.1%	3.4%
Tyres & wheels	1.0%	2.9%
Steering & suspension	0.4%	2.7%
Structure & body	0.9%	1.1%
Fuel & exhaust	0%	1.1%
Drive system	0%	0.9%

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	Royal Enfield Bullet Efi E4	Yamaha FZS600
2020	96.3%	83.6%
2021	84.6%	82.8%
2022	89.5%	83.6%
2023	90.2%	84.2%
2024	85.7%	83.3%
2025	93.3%	84.0%

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	Royal Enfield Bullet Efi E4	Yamaha FZS600
0k-10k miles	90.2%	89.6%
10k-20k miles	82.9%	85.5%

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

Royal Enfield Bullet Efi E4 vs Yamaha FZS600 FAQ

answers computed from the data above · terms in the glossary

Which is more reliable, the Royal Enfield Bullet Efi E4 or the Yamaha FZS600?

The Royal Enfield Bullet Efi E4 passes its MOT first time more often than the Yamaha FZS600: 89.6% vs 82.6%, a 7.0-point lead. Adjusted for age, mileage and test class the two are level (-0.1 vs -0.8 points against comparable bikes), so the raw gap is mostly down to how old and how used each fleet is. An MOT checks roadworthiness items, not engine or gearbox internals.

What does the Royal Enfield Bullet Efi E4 fail its MOT on most?

Lights & signalling: 2.1% of Royal Enfield Bullet Efi E4 MOT tests failed on it, then brakes (1.4%).

What does the Yamaha FZS600 fail its MOT on most?

Brakes: 4.5% of Yamaha FZS600 MOT tests failed on it, then lights & signalling (3.4%).

ROYAL ENFIELD BULLET EFI E4 89.6% pass · 897 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.