KAWASAKI Z400J

399cc Petrol Class 2

#4187 of 5426 overall #507 of 592 KAWASAKIs #2610 of 2787 other bikes

76.0%

first-time pass rate

12.8%

failed outright

29,111

median miles at test

533

MOT tests, 2005–2025

Pass rate over time

first-time pass rate by test year · 2006–2016

The Z400J's first-time pass rate has risen 8.0 points since 2006, 75.9% to 83.9%.

Pass rate by mileage

how the Z400J's first-time pass rate falls with the odometer · class average 84.9%

A low-mileage Z400J passes first time 64.4% of the time; by 50k that's 71.4%.

First-time pass rate by odometer reading at test, 10,000-mile bands for this model. Mileage is the strongest reliability signal. See the full curve.

What fails on a Z400J

failure defects by component group · advisories excluded

Component group	Defects	% of defects	vs all bikes
lighting and signalling	68	32.9	1.6×
steering and suspension	49	23.7	1.8×
brakes	37	17.9	1.1×
drive system	14	6.8	2.3×
tyres and wheels	11	5.3	0.9×
driving controls	7	3.4	4.8×
lamps and reflectors	6	2.9	0.4×
fuel and exhaust	6	2.9	1.2×
body and structure	5	2.4	2.0×
reg plates and vin	4	1.9	1.3×

Defects recorded against failed normal tests, 2005–2025, grouped by DVSA inspection section. One test can record multiple defects. "vs all bikes" is how often this model's tests record a defect in the group, as a multiple of the all-bike rate.

How rivals compare

same type, similar capacity, high test volume

On first-time pass rate the Z400J beats 0 of its 4 closest rivals (KAWASAKI ER5, SUZUKI GS500, SUZUKI AN400).

KAWASAKI ER5 77.4% pass · 53.1k tests SUZUKI GS500 76.4% pass · 44.9k tests SUZUKI AN400 86.2% pass · 27.1k tests SUZUKI DR-Z400S 80.4% pass · 26.8k tests

Rivals share this bike's type and sit within ±30% of its engine capacity, ≥ 5,000 tests. Card colour = better/worse first-time pass rate than the Z400J.

Pass rate by registration year

how each model-year cohort fares · registration year from first use date

Best year to buy used: 1980 (76.4% pass). Weakest: 1981 (72.1%).

First-time pass rate by the year each bike was first registered (cohorts with ≥ 50 tests). Older cohorts are survivors: the worst examples have already left the road, which tends to lift the earliest years.

KAWASAKI Z400J FAQ

answers computed from the data above · terms in the glossary

Is the KAWASAKI Z400J reliable?

The KAWASAKI Z400J is less reliable than average for its class: 76.0% of its 533 MOT tests (2005–2025) passed first time, against a class average of 84.9%. That ranks it #4187 of 5426 models.

What does a Z400J fail its MOT on most?

lighting and signalling — 33% of all defects recorded against failed Z400J tests.

What is the best year of Z400J to buy used?

By first-time pass rate, 1982-registered examples do best (76.4%) and 1981 worst (72.1%). Condition and history still trump the year.

How many miles will a Z400J last?

The median Z400J shows 29,111 miles at test, and examples around 50k miles still pass 71.4% of the time — mileage alone rarely kills one.