Jawa 350/639 vs Kawasaki ZXR400

The Jawa 350/639 passes its MOT first time more often than the Kawasaki ZXR400: 85.2% vs 73.1%, a 12.1-point lead.

MOT reliability, side by side

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

Metric	Jawa 350/639	Kawasaki ZXR400
First-time pass rate	85.2%	73.1%
Outright fail rate	7.8%	18.9%
Vs comparable bikes (age & mileage adjusted)	0.0 pts	-9.9 pts
Engine size	344cc	398cc
Rank among all models	#2445 of 5428	#4490 of 5428
Median miles at test	11,178	23,651
MOT tests analysed	769	14,200
Most common failure	lighting and signalling	lighting and signalling

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	Jawa 350/639	Kawasaki ZXR400
Lights & signalling	4.2%	9.1%
Steering & suspension	2.7%	7.9%
Brakes	2.1%	7.9%
Tyres & wheels	1.6%	4.0%
Structure & body	1.0%	2.2%
Fuel & exhaust	0.4%	2.4%
Drive system	0.3%	1.9%

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	Jawa 350/639	Kawasaki ZXR400
2009	81.8%	70.1%
2010	91.2%	68.5%
2011	72.9%	71.2%
2012	87.8%	69.5%
2013	85.7%	68.6%
2014	83.3%	70.6%
2015	86.5%	75.5%
2021	94.1%	81.2%

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	Jawa 350/639	Kawasaki ZXR400
0k-10k miles	86.4%	87.1%
10k-20k miles	83.1%	77.4%
20k-30k miles	88.4%	69.9%
30k-40k miles	84.4%	67.8%

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

Jawa 350/639 vs Kawasaki ZXR400 FAQ

answers computed from the data above · terms in the glossary

Which is more reliable, the Jawa 350/639 or the Kawasaki ZXR400?

The Jawa 350/639 passes its MOT first time more often than the Kawasaki ZXR400: 85.2% vs 73.1%, a 12.1-point lead. Adjusted for age, mileage and test class, the Jawa 350/639 still comes out ahead: 0.0 points vs comparable bikes for the Jawa 350/639, -9.9 for the Kawasaki ZXR400. An MOT checks roadworthiness items, not engine or gearbox internals.

What does the Jawa 350/639 fail its MOT on most?

Lights & signalling: 4.2% of Jawa 350/639 MOT tests failed on it, then steering & suspension (2.7%).

What does the Kawasaki ZXR400 fail its MOT on most?

Lights & signalling: 9.1% of Kawasaki ZXR400 MOT tests failed on it, then steering & suspension (7.9%).

Which holds up better at high mileage, the Jawa 350/639 or the Kawasaki ZXR400?

At 30k-40k miles the Jawa 350/639 passes first time more often: 84.4% for the Jawa 350/639 vs 67.8% for the Kawasaki ZXR400.

JAWA 350/639 85.2% pass · 769 tests KAWASAKI ZXR400 73.1% pass · 14.2k tests

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