Fuel Economy and Vacuum Lines

[The Dark Shadow]

Regarding your question asking what affects fuel efficiency. Just about everything does, but below are some examples and ideas for you to mull over.

General state of tune, which includes spark plugs/wires, ignition system, engine valve gap, 5-way Tee, thermostat, etc., etc., etc..

How you ride- Twist the wrist, fuel consumption increases.
How you ride- Riding at an RPM that is to low for the current speed increases fuel consumption. The ST1300 likes to above 3,000 RPM. At highway speed it returns better fuel economy with an RPM closer to 4,000 than 3,000. Many of us tried to convince you of this in your previous fuel efficiency thread where you were adamant that the ST1300 is geared to high and that the engine RPM is always to high. At the time you were asking about a means to modify the transmission and/or the final drive to lower the engine RPM's. If you remain convinced of this and are constantly lugging the engine the fuel efficiency will be affected.
Where you ride- lots of stop and go, fuel consumption increases. Lots of elevation changes, fuel consumption increases.
Tire pressure- The lower the tire pressure the higher the fuel consumption.
Strong head-wind, fuel economy suffers.
Obstructed airflow to the induction system. This is not limited to the cleanliness of the air filter. An obstructed intake tract has the same effect. e.g. Mouse nest.
Dragging brakes.
Riding the brakes. Some people keep to much pressure on the brake lever in anticipation of an needing to perform an emergency stop instead of just covering it in preparation. They don't realize that they are activating the brakes ever so slightly.
Excessive resistance to wheel rotation other than brake dragging. e.g. Failing U-joint, failing wheel bearings, improperly installed wheel bearing/wheels.

For comparison purposes to give you some exact real-world numbers calculated by dividing the consumption in to the distance driven, not based on the results of the on-board computer, below is the fuel efficiency numbers for my 2009 ST1300.
Note to the number crunchers- If you do the math it might not work out exactly because I use Excel formulas that I have set to round up/down. It is more than close enough, I don't need precision to the 5th decimal place for calculating MPG. I generally ride between 100 and 120 KPH GPS reported speed when on the highway.

The average fuel efficiency of all miles ridden since the motorcycle was new, so a true average, is;
55.5 miles per imperial gallon, 19.7 Km/L, 5.1 L/100 Km, 46.2 miles per US gallon.

The last time that I went to Nova Scotia it was getting to/from the Cabot Trail and the surrounding area. It was probably a more sedate ride than what you might do because I was with someone older, so there was no knee dragging going on. The numbers will be a little higher because of that, but not enough to explain the difference between what I am reporting and what you report.
My average fuel efficiency on that trip was;
57.6 miles per imperial gallon, 20.4 Km/L, 4.9 L/100 Km, 47.9 miles per US gallon on that trip.

You've said a lot...

Several things, like riding the bike, I'm WAY past... Although I'm a cr@ppy auto mechanic, as far as riding beasts I'm very well aware of brakes and ideal gear usage.

Stated above somewhere, I have observed and calculated based upon fill up consumption and km's driven, then compared to the onboard display. I know its error is consistent, and I calculate for this.
So far this tank, 90% highway driving @ 110-120kph, I've driven 237km and I'm down to 3 bars... Less than half a tank. Driving for fuel consumption not for the smiles. I'm getting AVERAGE 38.88mpg (US) including the last 3 tanks. I've gotten 47mpg on the flats, which is pleasing to me.

It seems that:

1. After my brake job, it took a few rides for them to settle in. I can feel when the brakes are, or aren't, binding even when I back down my driveway, and at stops when I'm on a slope (based upon how easily/quickly the bike moves clutch-in when brakes are released).

2. As someone commented on Facebook, low altitude, cold ambient temperature, and humid air really take the pi$$ out of this engine's fuel economy.


3. The gearing is NOT ideal for European and American roads. It is ideal for Japanese roads. I know this thorough direct experience, and I know the Japanese cultural mind intimately. They are insular in thinking. "Sakoku jidai" still exists in their thinking. My 4 cylinder cast, and my 6 cylinder car, operate near 2500rpm at highway speeds. Any more than this and you end up cruising in passing gear, affecting mileage detrimentally. The engine only needs to produce enough torque and power at highway speeds to overcome wind and rolling resistance, as well as to overcome the inefficiency of the engine. The faster the rpm, the greater the loss (ie: more energy is used just to spin the engine, fears, cramp shaft etc).

I'm cr@p at auto repair but I understand this mechanical concept stuff quite well. With different gearing, this motorbike could easily get an extra 15% fuel economy. You can disagree... That's fine.

My Shadow 750 was geared from factory at about 5000rpm @ 100kph. And this is for a LONG STROKE V TWIN! First thing I did was change the sprocket (I hired a Japanese mechanic who knew how to do his stuff correctly, unlike my experiences here) which DRASTICALLY improved EVERYTHING about the gearing. Then I had a custom belt drive kit made.

 

[The Dark Shadow]

Because I kept my mouth shut and my meat hooks off the keyboard, but I agree.
I've stated before, I use the onboard fuel "calculator" as an entertainment device, because it makes me laugh.
Meanwhile, recording the odometer and resetting the trip meter at every fillup will tell the truth.
I'm consistently returning 42mpg, but usually ride in a more sporting manner, but not excessive speed, just 70 - 80mph, mostly closer to the middle of those speeds.
(If you want to be technical, and mention the inaccuracies of the odometer, or variance due to tire wear, or the atmospheric pressure last Wednesday or the alignment of the planets, I don't do all that. Just a calculator, and consistent recordings.)

I've measured tank fill up's and calculated/compared to the onboard display enough times to observe consistent results, and I know the factor to compare against. It is consistent with a percentage offset that I use to calculate from the onboard display now. Never hurts for me to check for an 11th time, but all other times have been consistent.

 

[The Dark Shadow]

So, here's ANOTHER QUESTION:

I set my idle to 800...

Sometimes it idles at 800, but sometimes it goes to about 1100rpm.

This is NOT related to the fans turning on and off, which has an immediate effect on the idle speed.

Could this suggest that the wax thingy ma bob has gunk in it...?

The wax thingy seems to work as it is supposed to... That is, when the bike is cold, it idles at about 2000 rpms until it warms up and drops.

 

[The Dark Shadow]

10% variability in reported fuel mileage could easily be explained by regional blends of gasoline, or the weather, the road conditions, the temperature conditions, the rider weight and cargo. With Honda’s programmed fuel injection, it would not be expected to have any variation in the richness of the fuel mixture that wasn’t compensated for by one of two sensors, the most important one being the coolant temperature. If the thermostat is operating properly and the engine is running at the correct temperature there’s no point in trying to lean the mixture with a throttle body synchronization. That procedure only affects the idle and the immediately off idle fuel mixture and has nothing to do with the mixture in the mid range and higher range. That's handled by the ECU based on the airflow data sensor at the air box and O2 data from the exhaust stream.

Personally, I think that there should be at least a few tanks of gasoline run through any bike with the mpg calculation based on corrected distance mileage and fuel burn, not from any onboard mpg readings not corroborated against distance/fuel burn calculations, or a "ringer" mpg like my 59.4 mpg tank. That was held steady <55 mph, flat road, 100 mile loop with no stops right back to the same gas pump.

I didn’t see it specifically used in the thread, but wouldn’t put too much credence in the instant mpg per gallon read out on the dash. Over 1,100,000+ miles of reported rider information the ST1300 delivers 38 to 46 miles per gallon in the middle of the bell curve distribution.

I expect you were in 5th gear @55mph.

This is similar to my findings...

IT IS IMPORTANT TO COMPARE APPLES TO APPLES. This is why my observations and numbers are given based upon FLAT roads with NO WIND, or WIND CORRECTION (ie: if I drive out against the wind on a flat area, I drive back WITH the same wind and average these numbers).

So, all things levelled off, the bike gets its BEST POSSIBLE mileage at approximately 90 kph in 5th gear. (Showing that it is geared with a Japanese sakoku jidai mindset, for Japanese roads.) From there, every increase in speed comes with a corresponding drop in fuel economy. This means that the RPM @ 90 kph (near 3300 if memory serves, but it might be a tad lower) is the MOST EFFICIENT rpm range for this motor. This is NOT the most powerful, but it certainly has enough power and torque to operate at this rpm at 110kph or 120kph, yet the gearing does not allow for this. Remember, after a certain rpm your motor becomes less efficient - it starts fighting itself more and having more parasitic drag.

 

[Andrew Shadow]

So, here's ANOTHER QUESTION:

I set my idle to 800...

Sometimes it idles at 800, but sometimes it goes to about 1100rpm.

This is NOT related to the fans turning on and off, which has an immediate effect on the idle speed.

Could this suggest that the wax thingy ma bob has gunk in it...?

The wax thingy seems to work as it is supposed to... That is, when the bike is cold, it idles at about 2000 rpms until it warms up and drops

If your RPM drops to 800 RPM after the engine has been warmed up it is unlikely that the thermal valve is still influencing the RPM. The specification for normal operating temperature base idle speed is between 1,000 and 1,100 RPM. 800 is far to low. There are reasons for that and reasons why setting the base idle RPM to low can cause idle speed fluctuations.

 

[dduelin]

I expect you were in 5th gear @55mph.

This is similar to my findings...

IT IS IMPORTANT TO COMPARE APPLES TO APPLES. This is why my observations and numbers are given based upon FLAT roads with NO WIND, or WIND CORRECTION (ie: if I drive out against the wind on a flat area, I drive back WITH the same wind and average these numbers).

So, all things levelled off, the bike gets its BEST POSSIBLE mileage at approximately 90 kph in 5th gear. (Showing that it is geared with a Japanese sakoku jidai mindset, for Japanese roads.) From there, every increase in speed comes with a corresponding drop in fuel economy. This means that the RPM @ 90 kph (near 3300 if memory serves, but it might be a tad lower) is the MOST EFFICIENT rpm range for this motor. This is NOT the most powerful, but it certainly has enough power and torque to operate at this rpm at 110kph or 120kph, yet the gearing does not allow for this. Remember, after a certain rpm your motor becomes less efficient - it starts fighting itself more and having more parasitic drag.

No, my goal was riding a steady 45-50 mph in 5th but an occasional overtake required speeding up a little.

 

[The Dark Shadow]

No, my goal was riding a steady 45-50 mph in 5th but an occasional overtake required speeding up a little.

Point is, it seems, that optimal gas mileage is at a paltry 85-90kph... At 125kph (4500rpm, if memory serves), the thing drinks juice like it's water.

 

[W0QNX]

Showing that it is geared with a Japanese sakoku jidai mindset, for Japanese roads.)

and that is why it was named the "Pan European" bike...to ride in Japan at 55 mph?

There is no need to regear for the engine to rotate slower at 55 mph.

My bikes tach has sat on 4700 rpm for many many miles and gas mileage is the same year after year averaged over the year. 44 mpg US on regular 87 octane gas. I can't drive 55 around here without risking life. I'd get runnt over out on the big roads.

 

[dduelin]

and that is why it was named the "Pan European" bike...to ride in Japan at 55 mph?

There is no need to regear for the engine to rotate slower at 55 mph.

My bikes tach has sat on 4700 rpm for many many miles and gas mileage is the same year after year averaged over the year. 44 mpg US on regular 87 octane gas. I can't drive 55 around here without risking life. I'd get runnt over out on the big roads.

Plus the ST1100 Pan European was designed by Honda in Germany and the ST1300 is evolutionary not revolutionary. The V4 was refined by Honda of Japan but it took Honda of Germany to put it in a continent-crosser.

 

[Al st1100]

Point is, it seems, that optimal gas mileage is at a paltry 85-90kph... At 125kph (4500rpm, if memory serves), the thing drinks juice like it's water.

Yep

 

[The Dark Shadow]

If your RPM drops to 800 RPM after the engine has been warmed up it is unlikely that the thermal valve is still influencing the RPM. The specification for normal operating temperature base idle speed is between 1,000 and 1,100 RPM. 800 is far to low. There are reasons for that and reasons why setting the base idle RPM to low can cause idle speed fluctuations.

Okay, so I checked my manual.

It says to set at 1000rpm + or - 100. So, from 900 to 1100.

I set mine a bit lower (to 800) based on another fellow's comment (to a different person, not to me) on a Facebook st1300 group. Since I didn't remember, and he seems to be a knowledgeable participant, I tried 800. Thank you for pointing out that this is incorrect.

That said, now that mine is set to proper range, it still seems strange to me that the idle will be at 900 after the bike is still warmed up, but then later, after or during a ride, it idles at 1100rpm. So, it seems fickle, and I'm not sure why a setting of 900 doesn't stay at 900, or on the converse, a setting of 1100 doesn't stay at 1100...

Again, I wonder if the was seal idle control thingy-ma-bob could be getting gunked up, causing fluxuations like this...

Or, is this 200rpm fluxuation (about 22% fluxuations) just normal...?

 

[Larry Fine]

Does blipping the throttle have any effect on it, or twisting the throttle closed?

 

[The Dark Shadow]

and that is why it was named the "Pan European" bike...to ride in Japan at 55 mph?

There is no need to regear for the engine to rotate slower at 55 mph.

My bikes tach has sat on 4700 rpm for many many miles and gas mileage is the same year after year averaged over the year. 44 mpg US on regular 87 octane gas. I can't drive 55 around here without risking life. I'd get runnt over out on the big roads.

YMMV - Quite literally!!

Proof of the fact that the gearing isn't ideal for fuel economy above 90kph is this...

Drive your bike on the flats at a steady 90kph in 5th gear and observe fuel economy...

Then, do the same in 4th gear and observe fuel economy.

You will find worse fuel economy in 4th gear.

If you think the Germans designed this bike, I have a bridge to sell you in San Francisco called the Golden Gate... It may indeed have been designed in Germany by Honda Germany, and there might have been some Germans on the design team, but rest assured, the design team involved Japanese and final decisions were made by Japanese.

Based upon my memory of torque curve and power/torque for this bike, top torque is achieved near 4400rpm, top power near 5500rpm.

So, if I'm driving 125kph (about 4300rpm if memory serves), I'm in "passing rpm range", and anyone who knows even a little bit about rpms, power, torque, cars, and passing versus cruising is able to understand that the extra power for passing rpms is not conducive and antithetical to fuel economy.

You can disagree with this all you want... There's still people who believe the earth is flat... Truth is truth whether a person believes in it or not.

 

[The Dark Shadow]

Does blipping the throttle have any effect on it, or twisting the throttle closed?

Thanks Larry. I'm assuming you mean the idle speed...

No, flipping the throttle doesn't affect it.

 

[Larry Fine]

Thanks Larry. I'm assuming you mean the idle speed...

No, flipping the throttle doesn't affect it.

Then it's not a cable-type mechanical issue.

 

[Andrew Shadow]

Experience has taught us that this engine prefers to idle at or above 1,000 RPM regardless of what the specification states. I set mine at 1, 050 when it is at operating temperature and the cooling fans are not operating and it is very happy and stable there. Biggest cause of what you are describing, devoid of an actual system defect, is that it needs a throttle body synchronization. I know that you stated that it was done by a shop. Means nothing to me, that is where I would start.

 

[W0QNX]

YMMV - Quite literally!!

Proof of the fact that the gearing isn't ideal for fuel economy above 90kph is this...

Drive your bike on the flats at a steady 90kph in 5th gear and observe fuel economy...

Then, do the same in 4th gear and observe fuel economy.

You will find worse fuel economy in 4th gear.

If you think the Germans designed this bike, I have a bridge to sell you in San Francisco called the Golden Gate... It may indeed have been designed in Germany by Honda Germany, and there might have been some Germans on the design team, but rest assured, the design team involved Japanese and final decisions were made by Japanese.

Based upon my memory of torque curve and power/torque for this bike, top torque is achieved near 4400rpm, top power near 5500rpm.

So, if I'm driving 125kph (about 4300rpm if memory serves), I'm in "passing rpm range", and anyone who knows even a little bit about rpms, power, torque, cars, and passing versus cruising is able to understand that the extra power for passing rpms is not conducive and antithetical to fuel economy.

You can disagree with this all you want... There's still people who believe the earth is flat... Truth is truth whether a person believes in it or not.

FWIW, the back wheel spins nice and freely.

Also, I don't think there are bad questions.

Questions indicate both areas where a person is lacking understanding but also areas where there is a desire to learn.

I'm not going to reread all my posts, but certainly a few of my questions AFTER having done the procedure were to ascertain whether my back brakes were working as they should. Hence my questions, "Should the back rotor get warm?" "How warm should the rotor get?" "How much space should there be between the pads and the rotor?"

These questions should have been be easy to answer and easily help me determine if my brakes are working properly or not.

It seems as though my brakes are now functioning properly.

So I am thankful to EVERYONE who chimed in to help me out. Kudos!

FWIW, I've been through a lot of socio-psychological pressure and some physical challenges in my life... And I'm still in the midst of a lot of issues. And the way I turned out in the aftermath is such that I get psychological paralysis, anxiety, and stress doing new things that I don't fully understand. And, other than changing some outer stuff (handlebars, screens, mirrors on my former Shadow 750, etc), I don't particularly enjoy automotive maintenance. It is therapy for some people, but for me, it is like a trip to the dentist. Having a working motorcycle is my therapy and a way for me to relieve my burdens. But I live in the backwater of the world. People with get up and go got up and went. There's few good motorcycle techs here. None trustworthy that I know. Hence, having problems with my holy grail of bikes does really really bad stuff to my psychology. So give a man a break... Let him have his therapy, and don't suggest he ride a "simpler" bike. No matter what bike I own, my psychology won't change nor will the lack of good moto techs in my area.

None of my questions were wrong or bad.

If I ask about how to cut an apple, describing how to peel a banana isn't very helpful.

I will repeat to you, Larry... I very much appreciate your efforts to help, I recognize your willingness to help and your desire to help me through this process, and I'm truly sorry if my psychological state was tough for you. But that's just the damaged goods that I am...

I was going to discuss the claimed stats on ST1300 torque and horsepower by many (Rear-wheel peak horsepower is up 22 to about 111 at 7,750 rpm, and peak torque bumped by about 12 pounds-feet to 83.6 at 6,100 rpm, and many dyno run charts ) but I found and read more of your posts. I concede to you. You should get on that great ST1300 you have and ride more. Riding is good for what ails us all.

 

[maddog13]

When I had my ST it averaged around 42 miles per US gallon. I found on hot days it would improve to more like 47 mpg. This was riding around 120 to 140 kmp.
I don't understand why it was better on hot days but it was so with you living on the coast where it is cooler I think 40 mpg is not necessarily bad. Larry lives in Arizona so the warm weather will give him better mileage. As for Honda dealers working on ST's I found my local shop was not the best. These people make their money changing oil and tires not fixing weird problems.
Lots of the mechanics have never worked on a ST.

 

[Larry Fine]

Warm air is less dense than cool, so it ought to make the mixture richer.

 

[W0QNX]

Warm air is less dense than cool, so it ought to make the mixture richer.

You're backwards. Warm is less dense so it holds less oxygen and that means the ST1300 LEANS out the mixture. Hence better gas mileage when hot and high altitude.

My best MPG's are normally riding in the high desert area of the country. Even riding today at 89 degrees but only 300 feet altitude it was showing instant 55 mpg at times.

Maybe you meant the ST1100 runs richer. yup dang carbs don't lean out.