Engine architecture
125 single → 321 twin
The MT-03 (2016+) introduced a properly modern A2-targeted twin-cylinder engine. The 1996 SR125 and 2006 YBR125 were carbed singles aimed at CBT learners. The MT-03 is fundamentally a different category of bike — A2 sport-naked, not commuter.
Power gain
+30 to +32bhp
12bhp SR125 → 42bhp MT-03. More than triple the power. The MT-03 sits right at the A2 power limit (47bhp absolute max, 42bhp typical) — designed to be A2-friendly out of the box without restrictors.
Why this lineage shifted
A2 licence rules
European A2 licence (introduced 2013) capped power at 47bhp / 35kW. This created a market for bikes designed specifically for the A2 limit — fast enough to feel like proper bikes, not just commuters. The MT-03, Duke 390, Ninja 400 all came out of this regulatory shift.
Real cost change
+£2.7k
SR125 was £1,800 in 1996 (£3,600 today). MT-03 is £5,800 for 2026 — 75% more in real terms. But the MT-03 is also a fundamentally bigger bike — twin cylinder, double the power, twin-disc front, ABS, TFT. Hard to compare directly. The closest 2026 equivalent to the SR125 in spirit would be the Yamaha MT-125 at £5,150.
Weight comparison
+58kg
110kg dry SR125 → 168kg wet MT-03. The MT-03 is 53% heavier. Different bike, different mission — but worth noting that A2 bikes have grown significantly in mass over the years. ABS hardware, twin discs, larger fuel tank, longer chassis all contribute.
Yamaha A2 strategy
MT-03 + MT-07 ladder
Yamaha A2 bike strategy is the MT-03 (entry A2) and MT-07 (the de-restricted A licence bike for many riders). The MT-07 makes 73bhp standard but can be restricted to 47bhp for A2. Many A2 riders buy the MT-07 already restricted, then de-restrict it when they upgrade. The MT-03 stays as the genuine entry-level option.
Cheapest way in
£800
A clean YBR125 from 2006-2014. The CBT bike everyone learned on. Indestructible, simple, 80mpg, dirt cheap to run. Still legal for L-plate riders today. Probably the cheapest way to get a Yamaha into your garage. Different bike to the MT-03 but the spiritual entry point.
