Harley-Davidson Iron 883 XL N 13 vs Triumph Thunderbird

The Triumph Thunderbird passes its MOT first time more often than the Harley-Davidson Iron 883 XL N 13 — 87.8% vs 86.9%, a 0.9-point lead.

MOT reliability, side by side

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

Metric	Harley-Davidson Iron 883 XL N 13	Triumph Thunderbird
First-time pass rate	86.9%	87.8%
Outright fail rate	6.4%	6.2%
Median miles at test	6,700	13,106
MOT tests analysed	1,644	56,312
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.

HARLEY-DAVIDSON IRON 883 XL N 13 86.9% pass · 1,644 tests TRIUMPH THUNDERBIRD 87.8% pass · 56.3k tests

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