Horsepower is what lets you maintain a higher speed, but it is low end torque figures that figure in on how you accelerate off the line. How the bike performs overall, then you factor in both the torque and hp curves.

An example:

The Yamaha R6 may feel a bit sluggish to some off the line, but when you have the engine turning in the upper RPMs, it will take off like a rat wearing Reeboks that just did a couple of lines and downed a Monster energy drink.

The Honda Shadow may not have a lot of top end normally, but it has a torque curve that starts down real low, and pulls good right from the get-go.

A V-65 Magna seems to have good power on both ends, which means it feels like a locomotive at the start, and turns into the bullet train up top. (one HELL of a cruiser!)

 

You also have to consider weight of bike and you, combined.
My riding buddy rides a Suzuki S90 (1500cc), which has a lot more hp and torque than my S50 (805cc). It also weighs about 220 pounds more, so I have no problem, at any speed, leaving him behind. On the other hand, adding a passenger doesn't make as much difference to his bike as it does mine, so if riding two-up is a concern, a big, high-torque engine with long legs is what you want.

 

Just think of it as if you were going to buy a diesel truck instead of gas. The diesel may not be the fastest on the drag strip, but load it up with a ton vs the gas truck and will pull right away. I'm am never too caught up in HP, I want something that has a broad band of torque, way down low (2500rpms) all the way through about 8000. That is why I have been looking at the Bandit 1200/1250, it is praised for its wide torque band amongst many others. I'm not concerned about doing 100mph, but I want to get out first from light and be able to nail it 6th gear to pass.

 

I love my Diesel truck. Cruising down the highway at 2000 rpm's. Not fast, but I can charge up any hill pulling just about anything. The February issue of Motorcyclist has a review of 3 bike that although similar in engine size were way different in HP and Torque. The 3 bikes were a HD Iron, A Triumph Bonneville and a Moto Guzi Stone. According to them the bike with the best torque felt faster, even if it wasn't.

 

That's the reason I like my GL1100 over my old GL1000. Roughly the same horsepower and both were dressed, but the 1100 has noticeably more low end grunt, so it cruises much better IMO.

 

Ugh. You people. Making me do maths twice in the same week. And on Christmas. Just shameful...

Torque is a direct measurement of the amount of twisting force or "work" produced by the engine.

RPM is the speed at which the engine rotates.

Horsepower is the product of an equation that uses tq. and rpm to give a value to an engines "work over time." Expressed as the following:

(tq x rpm)/5252 = hp

Torque is a good way to understand the performance characteristics of an engine. Know where youre making your torque and you get a good idea of the powerband of the engine. When dealing with aftermarket parts, build for torque and the horsepower will follow. That means more torque everywhere, smoothing any gaps in the powerband.

Horsepower is useless. At least to me. Telling me a product makes +5hp doesn't give me any useful info. More often than not, aftermarket parts are a trade off. Sacrificing tq at one engine speed to boost output at another, while never really making "more" of anything. You can get a hp increase by making the same peak tq at higher rpm. That's not an improvement, that's gaming the numbers. Theoretically, you could get 150hp out of a 250 if you could get it to spin fast enough. It would also, theoretically, be unpleasant to ride.

On the factory review side, any engine that makes good useable tq across the full sweep of the tacho, with no dead spots or hesitation, is going to get smiled upon. Those qualities make for a predictable power unit that is easy to live with. No suprises, nothing to distract from the ride. Just an engine you can trust to do what you say, when you say it, with enough ability to get it done. Who's gonna complain about that?

 

Ugh. You people. Making me do maths twice in the same week. And on Christmas. Just shameful...

Torque is a direct measurement of the amount of twisting force or "work" produced by the engine.

RPM is the speed at which the engine rotates.

Horsepower is the product of an equation that uses tq. and rpm to give a value to an engines "work over time." Expressed as the following:

(tq x rpm)/5252 = hp

Torque is a good way to understand the performance characteristics of an engine. Know where youre making your torque and you get a good idea of the powerband of the engine. When dealing with aftermarket parts, build for torque and the horsepower will follow. That means more torque everywhere, smoothing any gaps in the powerband.

Horsepower is useless. At least to me. Telling me a product makes +5hp doesn't give me any useful info. More often than not, aftermarket parts are a trade off. Sacrificing tq at one engine speed to boost output at another, while never really making "more" of anything. You can get a hp increase by making the same peak tq at higher rpm. That's not an improvement, that's gaming the numbers. Theoretically, you could get 150hp out of a 250 if you could get it to spin fast enough. It would also, theoretically, be unpleasant to ride.

On the factory review side, any engine that makes good useable tq across the full sweep of the tacho, with no dead spots or hesitation, is going to get smiled upon. Those qualities make for a predictable power unit that is easy to live with. No suprises, nothing to distract from the ride. Just an engine you can trust to do what you say, when you say it, with enough ability to get it done. Who's gonna complain about that?

This^^^^.

Response to bolded section:

If I had had a dollar for every time I've heard someone say (or post on the interwebz), I bolted on 60 horsepower this morning. (talking about Honda Civics) I'd be able to take a month off of work....

Back on topic.

Some High HP bikes (in my opinion) are wasted on the streets. For me, (personally) I couldn't justify the cost/riding position of a CB-Ninj-kawi-busa-R1 if I couldn't take it out and running it to at least 80% of it's capability. I don't know of a place near me to do track days. If I had an RR or SS bike, I would feel like I was wasting the bikes potential. This is why I don't/won't own a bike like that.

My Buell XB9 (according to Buell) makes 92+ HP and 68 lbft tq and weighs less than 400lbs. It is some of the most fun I've had on 2 wheels. I can grab a hand full of throttle to get "that feeling in the pit of my stomach" and not even come close to "felony stop" speeds. I can also cruise at 80 MPH all day on the highway.

My last bike (Buell Cyclone) dyno'ed at 101.7 HP/91 lbft tq (with mods) and I used to squeal like a little girl in my helmet when I cracked the throttle @ 3500ish RPM. I could also enjoy a "spirited ride" on this bike and avoid triple digit speeds. This bike was more comfortable riding 2^ than the XB9 (1203cc vs 984cc) but neither feel sluggish with a passenger.

Both bikes have a fair amount of torque available from @2000 - 7000 RPMs. A decent rider on an R6 would smoke me in the 1/4 mi or a track with long straight stretches.

I would suspect that most v-twin sport touring/hooligan bikes would perform similarly.

 

I wonder how important horsepower really is on a bike...QUOTE]

Vito,

This is not a science project with lots of complex math!

Throw a leg over some bikes with more horsepower and see if it excites you to the point where you've gotta have it. If the answer is no, then horsepower is not that important (to you). If the answer is yes, we may be seeing your Triumph America posted in the classifieds!

I love horsepower. My daily ride has 163 HP with a curb weight of 531 LBS wet.

Oz
K1200R Sport

 

Horsepower is a series of numbers, the bigger the better, for silly old farts who's main aspiration is to be king of the pub car park.
Ask most of them to define what bhp actually means, and they wouldn't know.
Some of the best bikes I've ridden have been less than 50bhp.

 

Horsepower is a series of numbers, the bigger the better, for silly old farts who's main aspiration is to be king of the pub car park....

No need to put someone down if they want more or less out of life.

Older riders get my respect.

Horsepower is just a number - dish up as much or as little as you like.

I ride to a weekly biker breakfast most Sunday mornings. There are no HP braggarts there, just fun loving people who also love motorcycles.

A few weeks ago 2 guys from the Ducati dealership showed up - one on a new Diavel and the other on a new Panigale 1199. They tossed the keys to anyone who wanted to try them out! All takers came back smiling.

This Sunday a guy from the Sym dealership showed up on a Sym 150. Same thing - he tossed the keys to anyone that wanted to try it out! All takers came back smiling.

Oz
K1200R Sport

 

Castle explained it correctly but here it is in simple terms:

TORQUE:this is where you get your pulling power from idle to 5252 RPM

HP: This is where you continue that pull after 5252 RPM

 

Well,my bike and truck both red line well before 5200 RPM. Does that mean I have no horsepower?
I general though I agree with you.

 

No badlands you still have HP just not enough to get past 5200 RPM.

This is a general statement and applies mostly to gasoline engines that span the RMP range indicated.

Now a question for you, I'm guessing here but you ride and HD right? I thought they redlined 5.5-6k?

 

7-8k

 

The rev limiter will kick in at 6000 RPM on the current Sportster Evo. (Stock)

I believe the rev limiter is set at 5500 on the twin cams.

 

Yeap. I didn't specify, but you're correct: TC motors are set from the factory at 5500 to 5800, depending on the model. When doing a performance upgrade it's common to reprogram that to 6200 to 6500 without making any modifications to the valve train. The theoretical upper limit in both Evo and TC motors is in the 7000 to 8000 range.

 

Wow, none of my bikes redline below 9000. I shift at 6000 on all of them in regular riding. I've taken the Ducati to 8500.

 

My Buell Cyclone redlined at 7000 RPMs and my Buell XB9 revs to 7200 RPMs. The beauty is, I don't "need" to rev much higher than 3500-4000 for normal riding.

 

"It's just that I'm sick of silly old mid lifers, many of whome are new riders or born agains, going on and on about how important bhp is to them, when in reality most would be hard pushed to find the limits of a Puch Maxi."

I feel you man. The same thing happens here: Lots of people get together and talk and brag about HP and cams and performance and a lot of other things they don't really understand. I see it in mid-lifers on Harleys hanging around the bars, and young sport bike riders hanging around the Steak and Shake, and others at a coffee shop on their Beemers and Eye-ties with their matched outfits.

But you know what? They're having fun, and they're enjoying one aspect of motorcycling that THEY enjoy. It's not my thing or yours, but they paid their coin, they bought their ticket, and they're enjoying their ride. True, I think it's silly, but who am I to judge? Their conversations, or Internet posts, don't effect me one bit or take anything away from my motorcycle experiences.

Besides, I've made a butt-load of money off people that like to talk about HP and torque and performance and so forth, but don't honestly know how to balance a tire, switch out a cam, or tune a carburetor. (Or even how to SPELL "carburetor.")

So if you're sick of certain types of people, just don't hang around them. Easy, right?

 

But you know what? They're having fun, and they're enjoying one aspect of motorcycling that THEY enjoy. It's not my thing or yours, but they paid their coin, they bought their ticket, and they're enjoying their ride. True, I think it's silly, but who am I to judge? Their conversations, or Internet posts, don't effect me one bit or take anything away from my motorcycle experiences.?

I'm not suggesting otherwise.
The original question was
"I wonder how important horsepower really is on a bike, within reason".
And that's my opinion, although I have embelished it somewhat with my opinions on todays born again biker generation, who preoccupy themselves with bhp to the extent that they are denying themselves the fundamental pleasures that biking brings.
In other words, they don't really get it, which is why so many of them only stay for a few years before graduating to some other mid life pursuit, like hang gliding, or jumping off bridges attached to giant rubber bands.
The problem is that these people seem to make up the majority of our ranks, which means they dictate what manufacturers emphasize in their marketing.
It also means that when people like me and you, who dare to cover more than a few thousand dry miles a year come to part exchange, we get hammered because we've dared to use our bikes for the purpose they were designed for, rather than just the Sunday jaunt to the local park & pose venue.

 

todays born again biker generation,

Hey, I think I resemble one of those!

But all of my high HP and TQ is in my sportscar.

 

i guess maybe a bit off target for this discussion but I personally could care less about HP/TQ numbers - if it feels good - I'm good with it. A lot like the MGB i used to have - slower than slow but really fun to drive.

 

These days if it hit the gas, or turn the throttle and it does what I want it to do, in reasonable time, I'm fine with it. I spent years bolting blowers onto cars in search of dyno sheets. The funny thing is, you go too far and the #s are good, but your speed can be worse. Spinning tires are a waste of output after all.

 

I have a GSX-R600, that has 100 bhp. I also have a GS500, that I use for Moto Gymkhana, it has 50 bhp. Whenever I take the 500 for a trip, I find myself thinking "I should have taken the gsx". The additional power makes riding so much more fun. To me, that is. ymmv. I think it's also safer, because the extra power makes it easier to keep away from cars on a busy freeway.

 

You are making a classic mistake that so many people make, and that is not differentiating between power and torque.
Power only become relevant if you regularly ride near the red line.
Look at purpose built touring bikes.
Bikes that are designed to carry two people and luggage.
Are they fire breathing mega powered beasts ?
No, mostly not.
I regularly ride in the French alps, and the best bike I have ever had for the job is my 60bhp BMW R1200C which take me, the Wife and tons of gear effortlessly.
That's because it has an immense spread of torque throughout the rev range, meaning it can pull effortlessly up the steepest passes fully loaded.
Power is one thing, but torque is what really counts on the road.
Oh yes, and what you said about power keeping you away from trouble.
I hear this a lot but my experience as a Police traffic officer taught me that very often, it was that very power that got them into trouble in the first place.

 

Torque counts below 100 mph. All but one of my bikes can do the ton, and theoretically, the 360 is geared to hit 100, but doesn't have the horsepower to do so with a rider.

 

Cubic capacity also plays a big part.
My Guzzi 1100 Sport produces 85bhp.
I regularly ride with a bunch of Police riders on much more powerful bikes.
These guys are all excellent riders, and I never get left behind and I'm not having to work the engine very hard at all.
While those guys are playing tunes on the gearbox, my bike with it's infinitely superior torque pulls like a cat with it's ass on fire and fly past while they're busy changing gear.

 

My bike according to Kawasaki, has 141 lbs-ft of torque.
It also weighs close to 900 lbs. Then you add the wife and pulling a trailer and we are heavy.

I do roll though the gears and love the twisties. I just can't do them like the sport bikes. I still have fun with them, though.

So I like having all 141 of those lbs-ft.

The rear tires, not so much.

 

My requirement for engine output is simple:

It needs to do what I want it to do for my preferred method of riding.

Other than that, if I don't actually NEED gobs of go-fast then I don't WANT gobs of go fast.

Which is why my next bike purchase is going to be a Ural

 

+1 for the MtG avatar

 

So many things to look at number wise. BHP, torque, weight. I have a 2007 Honda VTX1800t. Very comfortable with plenty take off. My only concern is stopping. Really feels heavy when I need to stop short. So many dynamics go into the "perfect" ride. I would recommend allot of test rides to find what feels right.

 

You're so right! Also what's "perfect" will change over time. I've been riding 42 years - started in 1970 on a CB350. At the time I thought it was perfect.

My once perfect FLHPI police cruiser started feeling heavy when I connected with some new riding friends. I started looking for a second bike. Took my time and tested lots of different bikes. I bought one that weighs 300 lbs less than the Harley and has a bit more torque. It's perfect.

Oz
K1200R Sport

 

Enough is different to different people so that is up to them.

I don't like wishing for more if I am making a pass but other than that, it's not a big deal to me.

I do find something that is quick thought puts quite a smile on my face.

I loose me nerve on my own bike around 7 to 8K and am not sure I ever had the go handle fully twisted at that.

 

I've come to realize no matter what you buy and ride and how much faster it is or the more TQ it has, I always get used to it and wonder how can I make it more powerful.

Got used to my muscle car, think it is slow now. Got used to my truck and think it is slow now, got used to our X5 and thought it was getting slow, but after renting a 2011 suburban for a month, the X5 is quick again. I feel my atv is hardly moving after getting used to my cruiser. Really thought the brakes were sticking at one point. LOL.

Bottom line, you're body gets used to the power. I'm sure if I had a vette, after awhile I would be used to it and think it is slow.

With motorcycles : As long as you are always taking off and beating every car on the road in acceleration, you are going fast!

 

I find most bikes to have sufficient torque, or acceleration.
I used to ride around on a 260cc 14,7HP bike, and it worked fine for me.
It took nearly forever to go from 75 to 80MPH but acceleration generally was great over all the line!
The bike was only 380LBS (like 550LBS tops with me on it)

 

Depends on what you use the bike for. I considered getting a 250cc Ninja for my daily commute (30 miles each way on the interstate), but in talking with some 250cc ninja owners, I leaned that it would comfortably top at 80mph, but would be buzzing at 10Krpm by then. Considering that the average speed on that particular stretch of freeway is around 75-80mph, I got something larger instead...something that wouldn't have to struggle to cruise.

Of course, I would still get a small bike if I were living in the city where nimbleness and quick acceleration below 60mph can be an advantage..

Gotta have the "right tool for the right job"