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Discussion Starter #1
Bass brought up a point in the "spark plug removal" thread i wanted to get you guys' opinion on, namely the Vulcan not being a high revving engine.

I think we're selling the Vulcan a little short on it's abilities. We buy V-Twins because we like Harley's low rpm rumble that big two cylinders provide. Kawasaki tries to accomodate us by giving us a nice V-Twin, but their technology leans toward higher-rpm engines. So, the first thing we all do is alter the exhaust so we can hear the nice low notes better, and change the gearing to slow down the rpm to keep the note low at speed. So...

1. I think this is a lot higher revving engine than we give it credit for and,
2. I think Kawasaki is not quite in the boat with the American mindset of a low-rpm, high-torque desire in their V-Twins.

Whaddya think?
 

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Without a tach I have no idea what the RPM's are even doing on this bike.:eek:
 

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I guess the low- or high-revving characteristics says little about the "credit" we should give to an engine, in my opinion. It just contributes to the character of the engine and the entire "spirit" of the bike overall.

Just consider this:

I quickly checked out the Peak Torque and Peak Power characteristics of our Vulcans compared to some other bikes that I (purely intuitively) considered high revving (namely the Ninja's). Here is what I found out:

MODEL / Peak Torque (rpm) / Peak Power (rpm)

VN900 / 3,500 / 5,700
ZX6R / 11,700 / 14,000
ZX10R / 8,700 / 12,500

See my point? Very revealing numbers, IMO. The torque and power output profiles of these engines are very different. I am sure we can probably find the actual curves plotted on a graph somewhere on the web. The Ninja's torque plot will be much steeper and peaks considerably higher (relative to its range) that the Vulcan's.

Indeed, these Ninja's are four-cylinders so not exactly comparable but I think that even strenghtens the argument as the general rule goes the more cylinders the lower the rpm.

What do you guys think?
 

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I guess the low- or high-revving characteristics says little about the "credit" we should give to an engine, in my opinion. It just contributes to the character of the engine and the entire "spirit" of the bike overall.

-----

Indeed, these Ninja's are four-cylinders so not exactly comparable but I think that even strenghtens the argument as the general rule goes the more cylinders the lower the rpm.

What do you guys think?
Didn't you mean, the more cyclinders, the higher the RPM?

A better comparison engine wise might be 900 Vulcan, and a similar sized twin such as the Triumph Bonneville/America series, IMHO. Redline is about 1000 RPM higher on my 865 CC Thruxton Twin, but it has the advantage of a lighter valve train since it is a double overhaed cam engine (no rocker arms), and the Vulcan is a single overhead cam design and requires rocker arms for valve activation.

The 900 really does a pretty darn good job RPM wise, just look at Harleys 883 Sporster!
 

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Didn't you mean, the more cyclinders, the higher the RPM?
Actually it seems to be the rule the way I wrote: higher revs for smaller engines.

You can see for yourself -- if you like say the Toyotas, look at the torque and power peak rpms of say the 1.8L 4-cylinder Corolla and the 5.7L V-8 Sequoia. Or take the Aveo and the Suburban... :D
 

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Discussion Starter #8 (Edited)
Well, it looks like didn't know what the %[email protected]# i was talking about.

I'd agree that comparing the twins to the four cyl. crotch rockets isn't really a fair comparison. I was looking more to Harley and, after researching a bit, found i didn't know squat. Although getting info on the Harley is a little difficult, here's what i found:

.......Tq lb/[email protected]@RPM
900: [email protected]@6000
883: [email protected]@6000
1200:[email protected]@5200

I fully expected the RPM parameters of the 900 to come in a fair amount higher than the Harleys. There i go thinking again. Dang.
I'm still dropping the gear ratio of my 900 this winter though. I don't like searching for 6th gear
 

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I'd be kind of surprised to find a stock 900 off the floor that would dyno at 53hp. When MC magazine used one for their long term ride, they got a whopping 43hp on the dyno. You could most likely get the 53 with pipes/intake/processor, but off the rack? I dunno about that.
 

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To Muddy the water more.

Here is a copy of the Kawasaki MSO on my bike,

50.9 HP and no RPM or torque data.



The difference between the magazines and Kawasaki is probably in large part due to rear wheel power (magazines) and crankshaft power (Kawasaki).

50.9, oh well, I still think it is an absolutely great bike.
 

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My friend rides an 883 and when i got my 900 custom he took it for a ride and could not believe the bike was firstly so smooth by comparison and quick and the fact that it handled so well.
At highway speeds he struggles to keep up with us and gets very frustrated
 

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The Kawasaki, or any manufacturer for that matter, report HP and Torque at the flywheel. The dyno the magazines do read it at the rear wheel. All the moving parts, trans, pulleys, belt drive, all rob HP from the motor, this is why there is a difference in the magazin and the manufacturers.
 

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Discussion Starter #13
The Kawasaki, or any manufacturer for that matter, report HP and Torque at the flywheel. The dyno the magazines do read it at the rear wheel. All the moving parts, trans, pulleys, belt drive, all rob HP from the motor, this is why there is a difference in the magazin and the manufacturers.
That's what i was finding when looking the stuff up. Big differences in what magazines and manufacturers were saying for just that reason. And published stock dyno charts were hard to find because most folks were doing the dyno after they added performance parts.

I'm with you, Shiloh, I love this bike regardless of the HP rating. I really think the 900 is the perfect all-around street bike.
 

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FYI, if you go to the S&S Cycle website it has a dyno for the stock 900. They compare it to a modified 900 with exhaust and their air filters. I can't remember the numbers, I posted them someplace here on one of the air filter threads I think.
 

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Discussion Starter #16
The rev limiter on the 900 is around 7200rpm. 70mph is about 4100rpms.
This is what i meant by the 900 being a "higher revving" engine. It's certainly no 4-cylinder crotch rocket, but i think the Harleys normally redline around 6000. My concern with our motor is that we may lug it too much.
 

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7200 eh?

I hit the rev limiter in 4th today going home. Gunned it kind of hard turning right before opposing traffic caught up to me. Surprised me a bit.
How did it surprise you? What happened that made you aware of the rev limiter kicking in?
 
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