Total Motorcycle Community Forums

yeah, just wondering.

the only time im constantly gonna be riding hard is when, and i say when again and not if, i get some trackdays.

need positive thinking... trackdays... trackdays... i will have some trackdays!

VermilionX wrote: oh and i can do 75 at a much higher rpm at lower gears and that will use more of my bikes power compared to getting 75 on a higher gear. am i right?

BTW - This is not true. The amount of hp required to push your bike down the road at a given speed remains the same. Whether you're putting out xx hp in 2nd gear at 10,000 rpm or in 5th gear at 4,500 rpm, the engine is still delivering the same amount of power.

As I said in my previous post, it's highly unlikely that you'll unleash 1/2 of your hp under street conditions (unless you start riding like a maniac).

flynrider wrote:
BTW - This is not true. The amount of hp required to push your bike down the road at a given speed remains the same. Whether you're putting out xx hp in 2nd gear at 10,000 rpm or in 5th gear at 4,500 rpm, the engine is still delivering the same amount of power.

As I said in my previous post, it's highly unlikely that you'll unleash 1/2 of your hp under street conditions (unless you start riding like a maniac).

really?

so my bike's rated HP is 178 @ 12,000 rpm... is this for 6th gear only?

so i push my bike on 1st gear @ 12K rpm, it's still not gonna use all of the HP?

Unless your dragging a rolled-over semi truck what will you need 179HP in first gear for?

no no, i was just asking to get the concept behind "178hp @ 12K rpm."

since i thought it doesn't matter what gear you are on as long as you are at 12k rpm, you use 178hp.

so if that's not true then i wanna know what gear that rating is for.

unless im at the tracks, i don't think im gonna wait for my rpms to go that high before i shift up.

Shiv wrote:Couldn't tell ya. But if you're doing 5k revs in second and 10k revs in 1st to achieve the same speed, why needlessly kill your engine? Warranty or not.

It's doing twice the work so I'd assume it'd degrade at twice the speed.

Hey Shiv,

That sounds logical, but isn't quite the way it works. Revs don't make a whole lot of difference in engine wear unless you take it to extremes (like riding around at 10K in 1st all the time). A more important factor in engine wear is power output. This is what causes stress and wear on the critical components. If you're running an engine at 5K rpm in neutral, you are putting almost no stress or wear on it compared to running down the highway at 5K in 5th gear.

Running at excessively low rpms can wear out an engine much faster than running at high rpms. Extracting power from an engine at lower rpms involves generating greater cylinder temperatures and pressures, and consequently more wear.

The ideal case is a compromise. For highway cruising you should pick a gear and rpm that will give you decent throttle response, yet is not jerking you back and forth with small changes in rpm. For each bike/engine combo, this rpm will be different, but I've found that if you get a dyno chart, the ideal steady state rpm is right before the hp curve begins to steepen to its peak.

flynrider wrote: Running at excessively low rpms can wear out an engine much faster than running at high rpms. Extracting power from an engine at lower rpms involves generating greater cylinder temperatures and pressures, and consequently more wear.

practicing skills on a parking lot once a month won't be considered excessive, right?

VermilionX wrote:no no, i was just asking to get the concept behind "178hp @ 12K rpm."

since i thought it doesn't matter what gear you are on as long as you are at 12k rpm, you use 178hp.

so if that's not true then i wanna know what gear that rating is for.

unless im at the tracks, i don't think im gonna wait for my rpms to go that high before i shift up.

This is what I've been trying (not so successfully) to explain. 178 hp is a vast amount of power. If your engine were to generate anywhere close to that, at this stage in your riding career, you'd probably be out of control.

Horsepower is a measure of work. In order to get 178 hp at 12k rpm, you're bike had to be put on a dyno. The dyno gave your bike a resistance that it had to "work" against. Eventually, it demonstrated that it could do 178 hp worth of work at 12k rpm.

Does that mean anytime your bike is revving at 12k it's putting out 178 hp? Of course not. Think about it this way : You start up the bike in the driveway and rev it up to 12k in neutral. How much work is the bike doing? The answer is pretty close to zero. On the other hand, near the bike's top speed at 185 mph or so, you'd better be at 12k rpm because it's taking all 178 hp to overcome aerodynamic drag and keep you pushing through the air at that speed.

Two drastically different examples of power output at 12K rpm. Hope that helps.

flynrider wrote: This is what I've been trying (not so successfully) to explain. 178 hp is a vast amount of power. If your engine were to generate anywhere close to that, at this stage in your riding career, you'd probably be out of control.

Horsepower is a measure of work. In order to get 178 hp at 12k rpm, you're bike had to be put on a dyno. The dyno gave your bike a resistance that it had to "work" against. Eventually, it demonstrated that it could do 178 hp worth of work at 12k rpm.

Does that mean anytime your bike is revving at 12k it's putting out 178 hp? Of course not. Think about it this way : You start up the bike in the driveway and rev it up to 12k in neutral. How much work is the bike doing? The answer is pretty close to zero. On the other hand, near the bike's top speed at 185 mph or so, you'd better be at 12k rpm because it's taking all 178 hp to overcome aerodynamic drag and keep you pushing through the air at that speed.

Two drastically different examples of power output at 12K rpm. Hope that helps.

i see, thanks, now i get what you mean.

Once a month is far from excessive