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Kawasaki Brings Variable Valve Timing to the Mainstream with the Concours 14
By Alex Edge

When I last discussed variable valve timing and lift technology, I was writing about the future of sportbike engine development (see http://www.zxforums.com/forums/showthread.php?t=321). It came as something of a surprise, then, when I heard the rumors that the first application of TRUE variable valve timing in a mass-produced motorcycle would be a sport-tourer - specifically, Kawasaki's 2007 Concours 14.

It does make sense, however. For all its terrific top-end rush, the 1352cc inline four found in the 2006 ZX-14 does respond somewhat sluggishly in the lower rpm range, a problem that will only be exacerbated by the greater weight of the new Concours. For those of you who have been reading up on the ZX-14, you know that the soft low-end power can be remedied by removing the restrictive butterflies in the intake tract, but it is likely that this change would also increase the emissions below 7,000rpm (above which the butterflies are fully open).

For Kawasaki's engineers, using a variable valve timing system is a much more elegant solution. We don't know yet what form of variable timing will be used, but rumors suggest that rather than a two-valve/four-valve switchover (like Honda's Interceptor), it will be a true variable valve timing system. This will allow the Concours 14 to effectively use a smaller camshaft at lower RPM, which will boost low-end power and torque, while at the same time offering improved fuel economy and lower emissions.

I find it unlikely that the Concours motor will use a multiple-profile system (like Honda's VTEC automobiles), which would give a pronounced step in the power output at the change-over point. This could be a safety issue in such a powerful machine, as the jump in power might cause the rear wheel to break traction at an inopportune time. Instead, I suspect the Concours will feature a variable timing system that can advance or retard one or both of the camshafts by means of some sort of motor on the end of the cam. This would allow the cams to have less overlap at low RPM, which, as I said, will increase power and torque while reducing emissions and increasing fuel economy. At higher RPM, the cams can offer more overlap to sustain a healthy power curve.

Of course, it's much more complicated than that - most automobiles that use such systems also take into account throttle position and engine load (in addition to RPM) in selecting camshaft timing, which means the ECU can optimize for mileage under light-throttle, highway cruising conditions, and also optimize for power at heavy throttle openings.

As I said in my article about camshaft design, variable valve timing carries a host of benefits for any powerful motorcycle which is intended to be used over a broad RPM range (i.e. a STREETbike). The Concours 14 should show that it's usefulness extends beyond sportbikes to motorcycles of any type, and it's only a matter of time before other manufacturers follow in Kawasaki's footsteps.

Source: Motorcycle Daily
 

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Beansbaxter:

On the C-14, perhaps the VVT will eliminate the need for secondary butterfly valves like the ZX14 has. I don't think anyone will know till the bike becomes available and the specs are released. A few of the ZX14 riders who removed their secondary butterfly valves without adding a PC to compensate for the change in air/fuel ratio got a "surprise" when their bikes started running hot because of the lean mixture. Others added Rovinski's TRE. I think people did these mods because they were "upset" Kawi moderated the low end power delivery to help the rider maintain control of what is a very powerful engine.

Personally I think the C-14's VVT is going to be continuously variable and not like the VFR were two valves out of the four valve head are normally actuated up to a certain RPM and the other two are actuated above that RPM. This should allow for controlled power delivery but have lots of torque on the low end, plus allow the bike to really come on in power delivery once the rev's are up. By looking at pics of the right hand side of the engine, I'd guess the VVT system is going to use pressurized engine oil. The flow of oil will be controlled by an electric solenoid which will be controlled by the ECU.

As we all like to "tinker" with our bikes, I'm sure there are some who will "tinker" with the VVT, intake, and the exhaust system. First on alot of people's list will be the large fugly muffler! I am inline to receive the first C-14 at the local dealer. I plan on leaving the bike stock with no changes, including the large "fugly" muffler.
 

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The GTR1400/concours14(coughcough) has dual throttle shafts with tps on each shaft which would indicate that there are primary and secondary throttle blades.
The rumor is that the intake cam is driven by a chain form the crank. The exhaust cam is driven by a chain form the intake cam. The sprocket on the intake cam has an advancer built into it which will advance/retard the exhaust cam timing. How that is controlled is open to discussion but it appears that on the right hand side of the cylinder head there is an actuator that is mot likely driven by the ecm. At this point this is all conjecture, time will tell how close we are guessing.
 

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According to an article in MCN (uk) the GTR1400 will have a similar system to BMW's Vanos system as used in their cars. It is intake only but is a continuously variable system, not a step system.

As for the name, GTR1400, 1400GTR, Concours14, Concours1400, ZG1400, or even Doris are all fine by me so long as it fits me and makes me grin.
 

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Hello First post on this forum and i hope to make some meaningful contributions in the time to come.\

The GTR is high on my list, we (my girlfriend is the passenger) make at least 2 2week ( > 6.000 km) euro trips per year on our VFR VTEC and the one thing i do hope is that Big K will be able to keep down the maintenance cost.

VTEC on the viffer can be a real killer for the dealer. I've seen several 24K service jobs that take more than 8 hours!!!! for an experienced mechanic.

So i cant wait to hear the maintenance intervals and epected costs!
 

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True but i ride about 40.000km a year on my motorcycle (most with my girlfriend on the back) You could say we're kind of fanatic. so every eurocent counts with 6.000 km intervals.

I must admit i cheat every now and then because when on trips this would mean i should visit the dealer twice in one month for maintenance.

My oils haven't got time to degrade:lol
 
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