I refrained from commenting directly on the engine layout because I have no direct personal experience with an I4’s power delivery – and personal experience was what was asked for.
I’ve ridden parallel twins between 250 and 800cc producing power from 15hp up to 75hp. I’ve ridden a small V-twin, and a small V4. All are known for decent torque spread and lack of peak (btw- if you ever want to try “instant power” ride a BMW 800 twin – as long as you are moving it has smooth-acceleration-to-extra-legal-speeds-grunt that just isn’t imaginable on the Ninja 250 or other bike that needs to wind up).
As I’ve mentioned before, the tach on a ZX-6R is very telling. It has a with “low rev” zone extending below 5000rpm, a green “stay here” rev zone extending all the way up to the red line. That is an engine that should not be under revved.
Looking at dyno charts, everything I’ve ridden basically has a flat torque curve. You get to a minimum rev, and then it just makes the same torque from there to almost readline. The bike accelerates the same as you move up the revs, the push still feels the same. The I4, even a so called “detuned” one like the FZ6 has a rising torque curve. Flat for a bit, then you start to enter the enter the power band and it increases dramatically. The faster you go, the faster you accelerate.
In a super sport 600, that torque curve is quiet late. I’ve been told by some riders that their bikes have to be spinning as much 5000rpm just to move off the line (slipping the clutch). Otherwise the lack of torque stalls the bike. My personal guess is that the bikes could handle a lower rev than their riders say… but only a guess
Road oriented 600s (and early 90s or older SS), have more torque lower down at the cost of peak power. This means the engine doesn’t have as a high a minimum rev. But until you start to enter that powerband, the bike is making way less power than a twin does.
According to the reviews I’ve read, the Yamaha is pretty much the worst for this. Its engine is the least “detuned”, so you need to “rev the nuts off of it” to pull away from stops, making it a poor city bike compared to the others in its class.
Again, this is a personal preference thing. Some guys love revving their bikes every change they get. Some guys want a bike that “just works”. But I expect a bike that “just works” is going to be much easier to learn on.
I’d be interested in input from Ben and Fotobits, as they both have experience with both I4s and twins.
@ briderdt :
“I can’t imagine doing those maneuvers on my SV”
At my ERC I had to do all those manuevers again on my ZZR-250, it wasn’t bad. I did bascially as well as the more experienced guys on GS500s, old BMWs, and the like.
A few really experienced guys did ’em on SS 600s nicely. Three experienced girls did it on 800 pound Electra Glides!!!
But the guys who looked the best? Three brand new riders doing it on their CBR125s.
Learning on a little bike definitely has advantages.
“The two seconds between ‘Oh S**!’ and the crash isn’t a lot of practice time.”