Harley-Davidson XL 883 N Iron 20 vs Triumph Thunderbird

The Harley-Davidson XL 883 N Iron 20 passes its MOT first time more often than the Triumph Thunderbird: 90.3% vs 87.8%, a 2.5-point lead.

MOT reliability, side by side

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

Metric	Harley-Davidson XL 883 N Iron 20	Triumph Thunderbird
First-time pass rate	90.3%	87.8%
Outright fail rate	3.0%	6.2%
Median miles at test	3,340	13,106
MOT tests analysed	536	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 XL 883 N IRON 20 90.3% pass · 536 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.