Do you keep a mental note of what gear you're in??

[Susan]

I agree.

Doesn't matter what gear you are in anyways.

As far as people trying to shift into 7th gear??

Are you going 130 mph+? I don't see why you would be trying to shift upwards anyways unless you were going over that speed, you RPMs would be too low to warrant shifting upwards(on stock gearing).

I can think of a reason: gasoline isn't cheap.

At 100km/hr in 6th, I'm running at around 5000 RPM (stock), which is OK. (It is, right?) Not that I would ever ride like a hooooooon... :spank: but theoretically, if I were to be going a wee bit faster than that, I'm sure my frugal nature (and my sad, sad math skills) would make me try to shift up another gear just in case I could squeeze an extra little bit of mileage out of Precious. Unless it's twisties, of course.

 

[Neal]

I can think of a reason: gasoline isn't cheap.

I'm sure my frugal nature (and my sad, sad math skills) would make me try to shift up another gear just in case I could squeeze an extra little bit of mileage out of Precious. Unless it's twisties, of course.

Running at low RPMs to save gas is an old wives tale.

If you are Lugging (running to low an RPM) your engine you will be burning more gas than if you were in a higher RPM range.

To get the best mileage you have to be running in the Power Curve of your motorcycle.

Depending on the Design on the Engine, the best RPM for fuel efficiency could lowish, mid or even high RPM. What is best all comes down to the engineering. To know the answer for your engine, you would have to engineers recommendations for your engine.

 

[Ssky0078]

I try to, but usually use math. From looking at my rev counter 4th gear is rpm x 10, 5th is rpm x 11 and 6th is rpm x 12.

So if the tach shows 5 (5,000) rpm I am doing 55 mph then I'm in 5th. If the tach says 6 and I'm doing 72 then it's 6th.

Way too complicated. I've memorized exhaust note in different gears at different speeds, much easier
:BLAA:

 

[Ssky0078]

Running at low RPMs to save gas is an old wives tale.

If you are Lugging (running to low an RPM) your engine you will be burning more gas than if you were in a higher RPM range.

To get the best mileage you have to be running in the Power Curve of your motorcycle.

Depending on the Design on the Engine, the best RPM for fuel efficiency could lowish, mid or even high RPM. What is best all comes down to the engineering. To know the answer for your engine, you would have to engineers recommendations for your engine.

I will attest to this, My Fz1 loves high rpms. I've tried lugging on the surface streets, and have found it to make things worse. The only thing that helps is having a nice smooth launch, too much gas mpg suffers, too little gas mpg suffers and I'm a moving target. I tend to stay on the quicker side.

 

[fastar1]

Running at low RPMs to save gas is an old wives tale.

If you are Lugging (running to low an RPM) your engine you will be burning more gas than if you were in a higher RPM range.

To get the best mileage you have to be running in the Power Curve of your motorcycle.

Depending on the Design on the Engine, the best RPM for fuel efficiency could lowish, mid or even high RPM. What is best all comes down to the engineering. To know the answer for your engine, you would have to engineers recommendations for your engine.

You may be confusing fuel efficiency (km/L) with power efficiency (hp/L). Power efficiency is maximised at the torque peak with full throttle (peak BSFC).
Fuel efficiency is penalised by two things: RPM and throttle opening. If you could ride the bike around at 1000 rpm you would get optimal fuel efficiency but risk damage to the engine from lugging it too much. The best attainable fuel efficiency is by holding the lowest realistic RPM in the highest possible gear. On the fizzer that ended up being around 75km/h, and interestingly it seems to be around 75-80 for just about every vehicle I've ever owned. If you do a steady 75 in 5th or 4th gear you will be wasting fuel.

 

[PurpleZJ]

I try to, but I still occasionally try to shift into 7th gear. Lol

 

[Neal]

You may be confusing fuel efficiency (km/L) with power efficiency (hp/L). Power efficiency is maximised at the torque peak with full throttle (peak BSFC).
Fuel efficiency is penalised by two things: RPM and throttle opening. If you could ride the bike around at 1000 rpm you would get optimal fuel efficiency but risk damage to the engine from lugging it too much. The best attainable fuel efficiency is by holding the lowest realistic RPM in the highest possible gear.

Not true.

The best MPG is at the designed RPM by the engine engineers, which would never be that low.

 

[fastar1]

The engineers designed the RPM between 0 and 14,000. I'm not sure what you're trying to say.

 

[Susan]

Neal,

I'm not trying to be snippy, just making sure we're discussing the same thing.

This (semi-off-topic) discussion is not about lugging through a gridlocked city doing 5 mph in 6th gear (if you can even do that without stalling, I don't know, never tried it). Probably most of us would agree that's not advised for a variety of reasons. Not wanting to lug the engine is why I always give the shift lever an extra tap when I come to a stop. That, and I personally have a subnormal ability to know which gear I'm in at any given time.

I'm talking about 60 mph. Or 70 or 80 mph. Riding at 60 mph in 6th gear isn't anywhere close lugging the engine, and it's got to be using less fuel than than riding at 60 mph in 5th gear because according to the tach, those pistons are getting 20 percent more more action at 5000 rpm than they are at 6000 rpm.

And the whole "reaching for 7th" is just another way of saying either "I thought danged sure I was reaching for 6th but miscounted" or "Huh... I think I'm probably in 6th, which is where I want to be, but I'm going to check and make sure."

Does that clarify things?

 

[Neal]

and it's got to be using less fuel than than riding at 60 mph in 5th gear because according to the tach, those pistons are getting 20 percent more more action at 5000 rpm than they are at 6000 rpm.

That reasoning is common but also false. At lower RPM the time the pistons are receiving fuel in longer time period intervals. While at higher RPM you are receiving fuel in lower time periods.


Let me put it this way. You have 60 seconds, you may pour water for 30 of those seconds into a barrel. Whether, you poor water for 30 seconds straight and then stop for 30 seconds (1 rpm) or do 30, 1 second water pours (30 rpm)... you are still doing the same thing, pouring water for 30 seconds.

What is going to determine which one gets more is the speed at which the water or gas is being used, not the intervals or RPM.

 

[fastar1]

What is going to determine which one gets more is the speed at which the water or gas is being used, not the intervals or RPM.

Actually, both duration and frequency will determine the amount of fuel being used. What you are saying is that the reduced duration of fuel injection will more than make up for the increased frequency of injection. I am saying it can't. The reasoning is simply that it requires more power to run 75km/h in 5th than 75 km/h in 6th. More power means more fuel. There is no escaping this.

 

[Neal]

Actually, both duration and frequency will determine the amount of fuel being used. What you are saying is that the reduced duration of fuel injection will more than make up for the increased frequency of injection. I am saying it can't. The reasoning is simply that it requires more power to run 75km/h in 5th than 75 km/h in 6th. More power means more fuel. There is no escaping this.

No, not at all.. I am saying FREQUENCY has NO direct effect on the amount of fuel being used.

More power doesn't not always mean more fuel, furthermore less fuel can mean more power. That is why people pay money for custom DYNO tunes to find the right fuel to air ratios at different RPMs, seems you are the one that needs to do some "escaping".

 

[fastar1]

No, not at all.. I am saying FREQUENCY has NO direct effect on the amount of fuel being used.

I'm just gonna let that simmer there for a few days.

More power doesn't not always mean more fuel, furthermore less fuel can mean more power. That is why people pay money for custom DYNO tunes to find the right fuel to air ratios at different RPMs, seems you are the one that needs to do some "escaping".

That would be a reasonable argument if you were claiming that the bike is poorly tuned at 5000 rpm compared to 6000 rpm. But of course we have to assume that the tune is fairly well sorted out across the RPM range, until you get outside of the useable powerband.
In any case, all this theory aside, the proof is in the pudding. Ride 75km/h in any gear other that 6th gear, then try it in 6th gear and see how much further you get on a tank.

 

[Neal]

I'm just gonna let that simmer there for a few days.



That would be a reasonable argument if you were claiming that the bike is poorly tuned at 5000 rpm compared to 6000 rpm. But of course we have to assume that the tune is fairly well sorted out across the RPM range, until you get outside of the useable powerband.
In any case, all this theory aside, the proof is in the pudding. Ride 75km/h in any gear other that 6th gear, then try it in 6th gear and see how much further you get on a tank.

Let it simmer as long as it takes for you to understand a mathematical fact.

That isn't proof of anything, it only tells you about that one engine at that those RPMs levels.

I am going to repeat myself since you didn't get it the first time. The best RPM for MPG is going to be where the engineers designed the engine to run at best MPG.

Now, I want you try thinking like you are person designing an Engine.

Where would you make the best MPG on an engine? For most Vehicles low RPMs of course, cars non-sport motorcycle that are made for stop and go traffic riding on the street of course the engineer is going to make designed for Low RPM efficiency because that is where the vehicle is going to be operating the most.

However, motorcycles that for sport riding are not met for city stop and go riding they are met to be ridden at higher speeds and higher RPMs... Not surprisingly the engines are designed differently to accommodate the different purpose of the vehicle. The fast way to vaporize your fuel is the low RPMs on some of the super sport bikes.

 

[Monica A]

I was thinking more about this today (while on hubby's CBF1000, which doesn't have a gear indicator that I noticed). I decided that and as long as you have a speedo and a tach, and you have the little green light to alert you in case you've managed to put it in neutral, the gear you're in... is about as meaningful as ladies' clothing sizes (if you're a guy, just trust me that they're completely arbitrary). Speed and RPMs matter a lot.

Susan, I just noticed your tag line. I too love riding motorcycles but I LOVE reading romance novels. What's your author name? PM me if you want. I am always looking for new fabulous authors to read.

 

[fastar1]

Let it simmer as long as it takes for you to understand a mathematical fact.

That isn't proof of anything, it only tells you about that one engine at that those RPMs levels.

I am going to repeat myself since you didn't get it the first time. The best RPM for MPG is going to be where the engineers designed the engine to run at best MPG.

Now, I want you try thinking like you are person designing an Engine.

Where would you make the best MPG on an engine? For most Vehicles low RPMs of course, cars non-sport motorcycle that are made for stop and go traffic riding on the street of course the engineer is going to make designed for Low RPM efficiency because that is where the vehicle is going to be operating the most.

However, motorcycles that for sport riding are not met for city stop and go riding they are met to be ridden at higher speeds and higher RPMs... Not surprisingly the engines are designed differently to accommodate the different purpose of the vehicle. The fast way to vaporize your fuel is the low RPMs on some of the super sport bikes.

When the engineers are given a fuel efficiency target as part of the design brief, it is not a straight minimum consumption at steady throttle target like we are discussing but an EPA city/highway drive cycle target. The manufacturer sets recommended shift points that are used to run the bike through the test. If you want to talk about what the RPM the engineers "designed" for best fuel efficiency then this is a good place to start.

It so happens that the recommended shift points are at very, very low road speeds, as listed in the owner's manual. I can't find a copy now but I've seen it before and it's discussed here; Thoughts On Shift Points? - Yamaha FZ6R Forums - International FZ6R / XJ6 Motorcycle Community Forum

The recommended speed to shift to 6th is 60 km/h, which is even slower than I feel comfortable going but hey, you're the one who is making the point about doing what the engineers designed for. I still say 75-80 km/h is a healthy speed to cruise in 6th. You can go higher if you don't think the bike can run well that low, but you will absolutely be using more fuel, and you will absolutely be going against the engineer's "designed RPM".

 

[Neal]

When the engineers are given a fuel efficiency target as part of the design brief, it is not a straight minimum consumption at steady throttle target like we are discussing but an EPA city/highway drive cycle target. The manufacturer sets recommended shift points that are used to run the bike through the test.

... pretty sure you made that up off of nothing like your previous posts or you are talking about something completely different/irrelevant.


Anyways, back to the lower the RPM the better fuel efficiency (MPG) myth I was Debunking.

To recap: I was explaining to you that the best RPM to run for fuel efficiency on each engine is determined by its design characteristics, you can not just assume lowering RPM is better.

Here is a Fuel Island Plot of a diesel engine: From wiki
View attachment 50170

The blue lines are fuel efficiency (lower is better) and x- axis is RPM.

As you can see the best Fuel Effiency you can get is 206 and that is running the engine at about 2200 RPM, going up or down in RPM is going to reduce efficiency, aka the best RPM for that motor.

Also notice, that the maximum fuel efficiency at 1300 RPM is the same 3000 RPM, 220 for this particular engine.

Every Fuel Island Plot is different for every engine, you can not tell what is optimal without knowing the plot. You may be able to increase efficiency in your fuel by lowering RPM, raising RPM and sometimes either one is going to be an increase over where you are currently at. Their is no way of knowing for sure without having a detail analysis of your engine's characteristics.


Some more interesting things about fuel economy that result because of what I was explaining a second about how engine characteristics are not intuitive.

A study done on fuel economy vs speed.
View attachment 50169

Notice how ragged some of these lines are with multiple peaks and valleys.

I can just imagine this conversation with a guy who drives the 1997 Toyota Celica.

So how is the mileage on your car?

Oh, its good when i drive really slow about 25 mph, gets about 52 per gallon. I drive pretty much as slow as I can cause it loses so mileage when i go faster. My mileage goes down to 38 MPG when I get up to 40 MPH. I bought this car to save money on gas and I can stand paying more for gas so I never drive faster than that, can't image how bad the mileage would be then.


Well, what you need to do is push down on the peddle further and go faster 60 mph and you will get much better mileage, back up near 50 mph like you were before..

What do you think I am a fool? Push down on the peddle further to go faster is only going to use more gas, that isn't going to increase my MPG.

 

[fastar1]

... pretty sure you made that up off of nothing like your previous posts or you are talking about something completely different/irrelevant.


Anyways, back to the lower the RPM the better fuel efficiency (MPG) myth I was Debunking.

To recap: I was explaining to you that the best RPM to run for fuel efficiency on each engine is determined by its design characteristics, you can not just assume lowering RPM is better.

Here is a Fuel Island Plot of a diesel engine: From wiki
View attachment 50170

The blue lines are fuel efficiency (lower is better) and x- axis is RPM.

As you can see the best Fuel Effiency you can get is 206 and that is running the engine at about 2200 RPM, going up or down in RPM is going to reduce efficiency, aka the best RPM for that motor.

Also notice, that the maximum fuel efficiency at 1300 RPM is the same 3000 RPM, 220 for this particular engine.

Every Fuel Island Plot is different for every engine, you can not tell what is optimal without knowing the plot. You may be able to increase efficiency in your fuel by lowering RPM, raising RPM and sometimes either one is going to be an increase over where you are currently at. Their is no way of knowing for sure without having a detail analysis of your engine's characteristics.


Some more interesting things about fuel economy that result because of what I was explaining a second about how engine characteristics are not intuitive.

A study done on fuel economy vs speed.
View attachment 50169

Notice how ragged some of these lines are with multiple peaks and valleys.

I can just imagine this conversation with a guy who drives the 1997 Toyota Celica.

So how is the mileage on your car?

Oh, its good when i drive really slow about 25 mph, gets about 52 per gallon. I drive pretty much as slow as I can cause it loses so mileage when i go faster. My mileage goes down to 38 MPG when I get up to 40 MPH. I bought this car to save money on gas and I can stand paying more for gas so I never drive faster than that, can't image how bad the mileage would be then.


Well, what you need to do is push down on the peddle further and go faster 60 mph and you will get much better mileage, back up near 50 mph like you were before..

What do you think I am a fool? Push down on the peddle further to go faster is only going to use more gas, that isn't going to increase my MPG.

There's no need to be offensive Neal, I haven't made anything up. If there's anything that I haven't explained well or that you'd like to know more about or that just doesn't make sense, just point it out and I'll be glad to either correct my errors or try to explain better.

The part about fuel consumption drive cycles I referred to are explained here. My point is that manufacturers who design to a particular fuel efficiency target use this EPA test as their metric, because it's what the public is familiar with. Here's an example: "*Honda's fuel economy estimates are based on EPA exhaust emission measurement test procedures and are intended for comparison purposes only."

I also offered the manufacturer's recommended shift points for the FZ6 (6th gear from 60km/h), also in response to your statement about each manufacturer's "designed RPM". If that's not an indication of the bikes intended RPM range then what is?

While you are right that all that may completely different/irrelevant to what you were saying, it was my best guess in the absence of any explanation from you about what you meant by "designed RPM" or "engineer's recommendation". I still don't know what you mean.

Regarding that fuel map, it seems to confirm what I already suggested;

You may be confusing fuel efficiency (km/L) with power efficiency (hp/L). Power efficiency is maximised at the torque peak with full throttle (peak BSFC).

If you want to derive fuel consumption in different gears at a set speed then you need more info than what that map shows. A crude way of reading that map would involve comparing the same load requirement (road speed) at two different RPMs.
View attachment 50176
In almost every case, increasing RPM carries the engine into a higher fuel consumption range. The exception is at low-RPM, high-load scenarios (say, like crawling up a very steep hill carrying a passenger and using low RPM) but then that's exactly the type of engine lugging that I said was to be avoided.

In fact, a more accurate representation of the change in engine load at a fixed road speed would make those arrows point down, making the fuel consumption even worse according to that graph.

I like the other fuel economy versus speed graph, that's a nice find. I was able to dig up the source data here (PDF) and play around with it a bit. Interestingly, the one car that you cherry-pick from that graph (the Celica) is not actually listed in the source data! The chart also doesn't indicate which gear the cars were in to acheive those results, so it doesn't do much to contribute to this particular argument.

However the graph does support what I said earlier about the optimal speed range for fuel efficiency in my experience;

On the fizzer that ended up being around 75km/h, and interestingly it seems to be around 75-80 for just about every vehicle I've ever owned.

Every one of the cars tested had a fuel efficiency peak between 40-55 mph (64-88 km/h), right in my ballpark. If you chart the composite of all 8 cars together (p.84) it gives a nice smooth curve with a peak fuel efficiency at around 53 mph (which neatly explains how the US ended up with 55mph limits after the oil crises!)
View attachment 50177
But that comment about peak efficiency was just an aside anyways. I only pointed it out because I thought it was interesting, I didn't mean it as any kind of counterpoint to your claim about gear selection.

 

[Neal]

You simply do not understand what you are talking about.

These are the things you need to get in your head.

* Every engine is different and has a best RPM to run at. Above or below to optimum RPM is a decrease in fuel efficiency/power efficiency. The optimum RPM of an engine can be low, mid-range or high depending on how it is built.

* Fuel efficiency is directly proportional to power efficiency. This should be obvious even to those with no knowledge of physics or chemistry. What is powering your engine? Gas of course. Power is the rate of which energy is released, gas is stored chemical energy.

Part 1: How Power relates to distance travel.
Power= Energy/time = force* distance/time = force * velocity

Energy/force = distance (obviously high power efficiency and low force maximizes distance traveled)

Part 2: Power relationship to a motorcycle traveling

The Energy comes from the gas which is converted to mechanical power by the motor which gives the potential for motion.

*From engine stand point you want to run it at its optimum RPM to get the most power out of your gas.

The forces involved are: Friction, Wind Resistance, Changes in momentum(linear and rotational)

* From the forces standpoint you want to reduce wind Resistance and Friction by going slower. Internet says 60 mph is the upward limit for most vehicle.

-RPM has fixed velocity to it for each gear.

Part 3: Effectively using the potential power from your engine.

For simplicity in numbers, say you have a motorcycle that has has an optimum RPM is 10k, has a HP of 100 at that RPM and travels 60 mph at that RPM.

1) You maintain a constant RPM of 10k.

You equation looks like this: ( Friction + Wind Resistance)* velocity =power

That number is going to be fairly small probable less than 20 HP, but your engine is putting out 100 HP at the RPM. So what happens? 80 HP could have been used for travel is wasted.

2) How to not waste the horsepower and instead use it to produce more distance for your fuel

You have to accelerate. How much acceleration?

So than ( Friction + Wind Resistance + (Mass *Velocity2 -Mass*Velocity1) )* Velocity = 100 HP

Basically, as fast as your bike can accelerate.

****
What would this look like riding?

You would accelerate at fast as possible to your engines optimum RPM, not exceeding your limiting velocity(probable 60 mph).

Then you would pull in the clutch, close the throttle, and coast.

After bike drops to your lower velocity limit, RPM match your speed, release the clutch and accelerate as fast as you can to your upper limit... repeat the process over and over.

That is how you would get the max Miles per gallon.

 

[agf]

right you two this is becoming a tad tedious reading snide comments between the two of you regarding who understands what

start PM ing each other come to a consensus and post a final comment

and remember
BE NICE

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