Revving - What Influences Speed?

[Zealot]

Read a thread on the forums about R6 cam swapping, and I have to say it's an interesting read to hear about the increased pull in the higher end of the rev range. I've noticed that most supersports pull harder and faster than the FZ6 by a fair margin - and I've been wondering what the technicalities behind this are. Honestly, I'd sooner buy an R6 engine and try to swap it out - but it's interesting nonetheless.

As far as I can tell, the gearing is likely different in which supersports have gear ratios that would allow for faster acceleration. I would have thought that different gearing like our 1st and 2nd being 2.8 and 1.9 respectively could have been something more like 3 and 2.2, and so on and so forth - but apparently the 03 R6 has identical ratios from what I'm reading. Why is it that they're revving higher to maintain the same speed as our bike? Camshaft profile? I know I can cruise at 100kmh and 5K RPM, whereas if I'm correct an R6 would be at closer to 6K to match the speed. How does a camshaft profile influence this, exactly?

I know their engines are setup with more higher end than ours, and once you hit the powerband the RPMs fly up drastically - which with differed fueling and ignition timing would likely go up even faster. That is of course changed by the higher up redline which if I had to guess would also equate to the powerband moving slightly upwards in the range and being that much better.

Any sort of insider knowledge on this type of stuff would be appreciated. I'd love to learn more about this kind of stuff, and you guys seem to know a hell of a lot about it.

 

[FinalImpact]

What holds the Fizzer back is ignition timing. In 1st, 2nd and a lesser degree 3rd, the ignition timing keeps the nose on the ground. It has a far greater influence on Zoom Zoom than the cams.
However, couple it all together and the R wins...
Exhaust, cam timing, fueling, and ignition timing make it what it is...

With the exhaust improved, ignition advanced, and a proper fuel map, the bike is very lively and incredibly smooth! Its transformed!

 

[Motogiro]

To answer one of your questions, the cam profile has nothing to do with RPM to speed ratio The RPM to speed relationship is the transmission gearing and sprockets. Camshaft profile will have to do with lift and duration that actuate the valve. Valve designs will include the springs that returns the valve to it's seated position as well as valve mass and size that helps change mass inertia of the valve allowing it to change or move through it's positions at a faster pace per the cam profile. When these designs allow faster transitions which eliminate float the power band of the engine can be increased at higher RPM. This as mentioned previously will include ignition timing, fueling and exhaust design changes Keep in mind that the ratings of the engine should be matched with other specific designs of the bike to make that power band feasible in the overall design. The FZ6 power may in fact may be a better design in what is sacrificed at the possible upper end RPM poweband for better torque characteristics related to the bike's total design package.

These designs are complex and pretty fascinating!:rockon:

 

[TownsendsFJR1300]

Slightly off off topic but related.

Someone did try to put an R6 engine in an FZ(I don't know if he ever finished it) but it was EXTREMELY INVOLVED. It'd be easier to get an R6 and raise the bars, etc (make it more comfy).

Now, a very easy way to wake up the bike is simply a sprocket change. A smaller front, larger rear, sprocket(s).

Of course if you did a bunch of highway riding, the RPM's will be higher.

You'd be shifting sooner, faster but would indeed make a very noticeable difference..


And just to add, the R6 likes the higher RPM's, which for a road bike, your NOT going to be running 12k most of the time but way below that.

With the stock gearing on the FZ capable of roughly 60 MPH in first, 2nd gear short of 100 MPH, you still have 4 gears left! IMO, simply changing the gearing is a simple, cheap and easy way to REALLY WAKE up the bike..

 

[Zealot]

I see now. Thanks for all the info guys - that makes a lot more sense!

Not really looking for a genuine supersport, but I was curious about the things that separated this bike from one!