YAMAHA RD400

398cc Petrol Class 2

#1400 of 5426 overall #56 of 409 YAMAHAs #854 of 2787 other bikes

88.6%

first-time pass rate

5.6%

failed outright

19,686

median miles at test

3,477

MOT tests, 2005–2025

Pass rate over time

first-time pass rate by test year · 2006–2023

The RD400's first-time pass rate has risen 7.7 points since 2006, 86.1% to 93.8%.

Pass rate by mileage

how the RD400's first-time pass rate falls with the odometer · class average 84.9%

A low-mileage RD400 passes first time 89.3% of the time; by 50k that's 97.2%.

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 RD400

failure defects by component group · advisories excluded

Component group	Defects	% of defects	vs all bikes
lighting and signalling	169	36.4	0.7×
brakes	122	26.3	0.6×
steering and suspension	61	13.1	0.5×
tyres and wheels	44	9.5	0.5×
body and structure	14	3	0.5×
lamps and reflectors	13	2.8	0.2×
drive system	13	2.8	0.5×
fuel and exhaust	12	2.6	0.4×
reg plates and vin	9	1.9	0.5×
suspension	7	1.5	0.2×

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 RD400 beats 4 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 RD400.

Pass rate by registration year

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

Best year to buy used: 1975 (94.2% pass). Weakest: 1977 (87.3%).

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.

YAMAHA RD400 FAQ

answers computed from the data above · terms in the glossary

Is the YAMAHA RD400 reliable?

The YAMAHA RD400 is more reliable than average for its class: 88.6% of its 3,477 MOT tests (2005–2025) passed first time, against a class average of 84.9%. That ranks it #1400 of 5426 models.

What does a RD400 fail its MOT on most?

lighting and signalling — 36% of all defects recorded against failed RD400 tests.

What is the best year of RD400 to buy used?

By first-time pass rate, 1975-registered examples do best (94.2%) and 1981 worst (87.3%). Condition and history still trump the year.

How many miles will a RD400 last?

The median RD400 shows 19,686 miles at test, and examples around 50k miles still pass 97.2% of the time — mileage alone rarely kills one.