Walk past an Exciter in Hanoi and the badge says VVA. It stands for Variable Valve Actuation - Yamaha’s system that changes how the engine breathes depending on revs. Here is what it does, based on what Yamaha Vietnam actually publishes (retrieved 23 September 2026).
What variable valve timing is
An engine’s valves open and close to let fuel-air in and exhaust out. When to open them is a compromise: settings that help low-rpm torque hurt high-rpm power, and vice versa. A variable valve system changes the timing (or lift) as revs rise, so the engine behaves like two engines - a flexible economy motor at low revs and a power motor at high revs.
What the Exciter’s page actually says
Yamaha Vietnam lists the Exciter 155 VVA engine as: 155 cc, four-stroke, single cylinder, four-valve, SOHC, liquid-cooled, VVA and EFI - producing 13.2 kW (17.9 PS) at 9,500 rpm and 14.4 Nm at 8,000 rpm, with a claimed 2.07 L/100 km.
Read those numbers together: a high-strung 9,500 rpm power peak usually means a weak bottom end, and a claimed 2.07 L/100 km is remarkably frugal for 13.2 kW. That combination is the practical evidence of VVA - the engine can be tuned for top-end power without sacrificing low-rev flexibility and economy the way a fixed-valve engine would.
Why it matters to a Vietnamese rider
In city traffic you spend your day between idle and 5,000 rpm. On the weekend ride you use the top of the rev range. VVA is why the Exciter can be both the commuting semi-racer and the fuel-sipping daily bike - it is also why the Exciter tops our verified fastest-under-155 ranking while holding the best economy claim of the three manual sport bikes.
What VVA is not
It is not a turbo, not a bigger engine, and not a substitute for gearing: the six-speed gearbox and Assist and Slipper clutch do work VVA cannot. Yamaha publishes VVA only on the Exciter in this verified range - do not expect it on smaller bikes’ pages.
Seeing it for yourself
The Exciter 155 VVA is not one of our price-published rental models - contact us to confirm current availability. Insurance is not included in rentals - customers arrange their own.