Sixth Generation
The sixth generation VFR (for the first time marketed only as the "Interceptor" in the USA) was introduced in 2002. For the first time it featured dual underseat exhausts, an optional anti-lock braking system (ABS) in addition to the DCBS, and optional hard luggage. It featured chain-driven cams rather than the traditional VFR gear-driven cams, and was the first motorcycle to have Honda's VTEC valve-actuation technology. The implementation of VTEC was seen as a bid by Honda to meet tightening noise and emissions standards in Japan and abroad while improving the peak horsepower of the engine. Similar to the automotive version of VTEC-E the simplified motorcycle version of VTEC employs only two of the four valves per cylinder when operating at lower engine speeds. All four valves per cylinder were engaged above 6,800 rpm. This is initiated by an electronically actuated oil spool valve, which send oil pressure to the lifter actuators, which then move the engagement pins into place above the valve stem, allowing the remaining two valves to open. This design allows for variable valve timing as well, since the cam lobe profiles could be made different. It is speculated that the duration of valve lift and overlap on the below and above 6,800 RPM valves differ. After some criticism of the abruptness of power transition, Honda lowered the VTEC activation rpm threshold to 6,400 rpm in 2006. The VTEC disengages two cylinder valves when the engine speed drops again below 6,100 rpm. For 2009, there were no significant changes to the VFR800.
Read more about this topic: Honda VFR800
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