Speaking of power, the headlines are dominated by changes to the cylinder head group and induction modifications. Featuring finger follower valve actuation most recently adopted by the Superbike world championship wining Ninja ZX10RR, this new direction facilitates a higher rev celling and more aggressive
camshaft timing whilst reducing overall valve train weight.
Boasting an increase in peak power of
approximately 2.4 kW (3.3 PS), and
performance focused on the high rpm
range, the stronger high rpm
performance is easily noticeable
from 10,000 min and gives riders a
special advantage on the straights.
Combined with a higher rev limit, it’s
now easier to tie corners together for
quicker lap times.
Additionally, a revised airbox
construction features a shorter (120 mm >
70 mm) tapered intake funnel, which
contributes to increased high rpm
performance. Another KX250 innovative
feature is the dual injectors a feature since
2012 utilising an injector downstream of the
throttle valve (where injectors are located on
standard FI systems). With that in mind, the
larger diameter (ø43 mm >> ø44 mm) throttle
body flows a greater volume of air, contributing
to increased high rpm performance, while
repositioning the intake duct allows an even straighter
approach for intake air. Finally, downdraft-style
intake routing increases the intake air’s approach
angle into the cylinder from 29.5º to 32.5º,
improving cylinder=filling efficiency and
contributing to increased engine power.