Fuel economy is terrible!!

[The Dark Shadow]

Lets go back to you earlier readings with the oxygen sensors, start looking for a vacuum leak. Put a vacuum gauge on the intake and see what the reading is, Try switching the sensors to the opposite side. The other thing that is worth checking is to pull the plugs and re-inspecting, they will show either rich or lean. Rich or lean both will ruin fuel economy.
Some of the manufactures have been quietly known to adjust the speedo to run out the warranty sooner. But that opens up a discussion that does not pertain to mileage issues. Just thought I would throw that in for fun.
Remember KISS....Keep it simple and start at the basics, What effects fuel air ratio if none of the sensors or codes show and one of the main ones I have commonly seen is unmetered air on the intake side.

Thanks for this...

Here's some thoughts...

1) I don't have vacuum gauges.
2) I read someone who is much smarter with engines than I that he replaced (and recommends replacing) ALL the vacuum hoses in this motorbike. At the same time, if I do this myself, I could pull the 2 or 3 5-way tees and ensure their cleanliness.
3) I intend to pull the plugs to check and see if one is running rich. How do I tell if one is running lean...??
4) How easy or hard is it to remove the O2 sensors...?? Removing them and having a visual inspection should help me assess if one (or both) are getting terribly clogged with carbon build-up.
5) Since it seems as though the ST13 standard speedo/odo runs so the speedo shows higher than actual speed, but the odo reads close to true, mine with a "Speedo Healer" runs pretty close to perfect for speed, and about 6 percent short on km. So if I drive 400km on my odo, I'm really driving 424km. But if my speedo shows 100kph, I'm going 100kph. The speed is corroborated with street-side radar speed indicators, live GPS on my bike (cell phone), and with the police... (you likely don't have to ask me about this last one... lol)

When I do my fuel economy calculations, I take #5 above into account.

 

[The Dark Shadow]

There is something that is causing your increased fuel consumption. It is not the gear ratios. Every ST1300 has the same gear ratios and they all consume much less fuel than what you are reporting. You can change gears ratios if you like, but it should be because you want lower RPM, not to fix your fuel consumption problem as that is treating the symptom. The cause of the increased fuel consumption needs to be found and dealt with.

The wording is backwards but the example is correct. With no speedo healer the factory ST1300 speedometer indicates higher than true speed, not lower.
Most people report that it reads in the 7% higher range.

2nd point... Yes, I should have written that non-healer speedo shows higher, rather than lower, than true speed. My bad.

Whether engine performance and fuel economy is "correct" on my bike or not, a taller gear ratio will necessarily improve fuel economy. The thing runs at too high of an rpm even at 100kph. Again I have this same experience with another short-geared Honda bike. To enable best fuel economy at highway speeds, the gearing should be such that the engine runs at or near lowest possible rpm to maintain cruising speed. This ST13 engine has plenty of power to keep it moving along at 110kph at 3500rpm (I'd expect it would even do fine at 3250 or 3300rpm), but it does not have a gear ratio to allow that speed unless it is at 4000rpm or a touch higher...

I lived in Japan and motorbiked there for 5 years. Most rural roads are 60 to 70kph maximum. That would be ideal for this bike's gearing. Japanese are very insular in their thinking (I'm married to one, have worked 11 years with Japanese, and studied and speak/read/write their language... Many Japanese friends joked that I have a zipper in my back and a Japanese person is hiding inside). Along with the insular thinking, I believe, is their approach to gearing for their motorbikes - at least for Honda. Do you know, they don't sell these bikes directly in Japan...? You have to do "gyaku yuunyuu" (reverse import) where the bike is sent to a foreign market for sale, then it is imported to Japan as a foreign bike. Otherwise, they don't sell bikes (or didn't, laws might have changed in the last 10 to 15 years) of a certain displacement and higher. It is either displacement or power, perhaps both. So, again, I hold true to my belief that this bike would run much more fuel efficiently if it had taller gearing or an extra gear. Even for accelerating, taller gearing would likely prove more fuel efficient.

 

[diferg]

@The Dark Shadow Your fuel mileage is BAD and your engine is "Galloping" or Hunting as we say around here. The two problems are definitely related! when you cure one you will find the other is corrected. I STRONGLY believe you have a vacuum leak! If you have a cruise control unit they are notorious for vacuum leaks. After having your exact symptoms I discovered cracked hose on vacuum fitting and threw my cruise control in the trash! At any rate the most likely culprit is a loose or cracked vacuum canister, hose, fitting or clogged 5 way "T" connector. good luck finding the source of this problem. unless you have very deep pockets, I would have very little faith in your local Honda Mechanic.

 

[The Dark Shadow]

@The Dark Shadow Your fuel mileage is BAD and your engine is "Galloping" or Hunting as we say around here. The two problems are definitely related! when you cure one you will find the other is corrected. I STRONGLY believe you have a vacuum leak! If you have a cruise control unit they are notorious for vacuum leaks. After having your exact symptoms I discovered cracked hose on vacuum fitting and threw my cruise control in the trash! At any rate the most likely culprit is a loose or cracked vacuum canister, hose, fitting or clogged 5 way "T" connector. good luck finding the source of this problem. unless you have very deep pockets, I would have very little faith in your local Honda Mechanic.

No deep pockets here, but I did empty out my savings trying to do some educated-guess maintenance. Sadly, with EFI engines, there's a lot of shooting in the dark even for the best of pros, it seems.

A fellow on a FB forum suggested to replace all the vacuum hoses. This makes sense now, based upon what your (and another's, if memory serves) suggestion of a vacuum leak which could be the key. It makes logical sense to me. The intake valves were vacuum checked and reported to be "perfect". The 5 way Tee was removed and checked, and reported as all clear (the main one, I'm guessing, since there are more than one listed in the parts diagram when I went to order an extra one, just in case, which I did not order).

Once I get a chance I'm gonna pull my plugs to observe them to see if one or two are running rich. I don't know the signs of running lean... I'll report back once I checked the plugs.

 

[MidLife]

4) How easy or hard is it to remove the O2 sensors...?? Removing them and having a visual inspection should help me assess if one (or both) are getting terribly clogged with carbon build-up.

Had an O2 sensor issue once with a cage, close to what I think you mentioned before. The sensor wasn't bad enough to throw a code, but still borderline enough to fool the ECM. New sensor and it all went back to clockwork.

Looks like some sometimes see improvement with just cleaning the sensor.

I also ran a slightly oversized windshield for a while, and that was robbing mileage as well.

You may want to try a run without windshield at all (remove it) for comparison.

But be ready....you may like the windshieldless ST so much that you'll never put it back on!

 

[Andrew Shadow]

2nd point... Yes, I should have written that non-healer speedo shows higher, rather than lower, than true speed. My bad.

Whether engine performance and fuel economy is "correct" on my bike or not, a taller gear ratio will necessarily improve fuel economy. The thing runs at too high of an rpm even at 100kph. Again I have this same experience with another short-geared Honda bike. To enable best fuel economy at highway speeds, the gearing should be such that the engine runs at or near lowest possible rpm to maintain cruising speed. This ST13 engine has plenty of power to keep it moving along at 110kph at 3500rpm (I'd expect it would even do fine at 3250 or 3300rpm), but it does not have a gear ratio to allow that speed unless it is at 4000rpm or a touch higher...

, taller gearing would likely prove more fuel efficient.

Of course different gear ratios will improve fuel efficiency, if geared properly. That isn't the point. The point is that there is something wrong with your ST1300 that is causing abnormally high fuel consumption. Even if you change the gear ratio, and your fuel consumption drops, that problem will still be there. You need to find that problem and fix it regardless of whether you want different gear ratios or not. If you don't, you will continue to burn fuel for no reason continuing to burn money for no reason in addition to what the gear ratio change cost you

More importantly, allowing the cause to persist runs the risk of it developing in to a bigger and more serious problem that can leave you stranded or worse lacking full power when you need it to escape an impact.

Your ride, your choice of course. I would fix the first problem first.

 

[step.leahy]

How are your tyres and suspension. I have a 2004 with 120,000 km (Australia) and noticed a deterioration in mileage. I've recently replaced the rear shock absorber (with genuine) and noticable improvement. back end was bouncing around a bit and chewing out tyres. Went from 6l/100km to around 5l/100km.

 

[Larry Fine]

I just saw a car specialist on youtube mention he was getting 36mpg from his Toyota Matrix on the highway at 70mph. I find it hard to believe that this 1.261 litre engine motorcycle can't even beat a friggin Toyota Matrix for gas mileage...

Maybe, but you had way more fun.

 

[Larry Fine]

1st gear is so short that I gotta change into second IMMEDIATELY...!!

Agreed. I often find myself shifting into second on my 1100s while still turning after a stop.

 

[Larry Fine]

3) I intend to pull the plugs to check and see if one is running rich. How do I tell if one is running lean...??

The porcelain of a very lean-running plug will be bright white instead of off-white, and possibly sparkly.

 

[diferg]

@The Dark Shadow you said the mechanic said your Intake valves tested perfect for vacuum. was he talking about the intake valves in the cylinder head or the starter valves in the EFI system? a bad valve in the cylinder head would have no effect on a vacuum leak in the EFI system. I agree with the person who suggested replace the vacuum hoses. they are not expensive but will be labor intensive. I suggest remove a hose to determine inside diameter and buy bulk Vacuum hose from auto parts store (be sure it is vacuum hose). this will be MUCH cheaper than buying designated hoses from Mother Honda! Try to make replacement hoses as close as possible to original lengths. Good Luck. Your problem is one of those that will be easy to fix when you find it, but Very hard to find!

 

[The Dark Shadow]

Of course different gear ratios will improve fuel efficiency, if geared properly. That isn't the point. The point is that there is something wrong with your ST1300 that is causing abnormally high fuel consumption. Even if you change the gear ratio, and your fuel consumption drops, that problem will still be there. You need to find that problem and fix it regardless of whether you want different gear ratios or not. If you don't, you will continue to burn fuel for no reason continuing to burn money for no reason in addition to what the gear ratio change cost you

More importantly, allowing the cause to persist runs the risk of it developing in to a bigger and more serious problem that can leave you stranded or worse lacking full power when you need it to escape an impact.

Your ride, your choice of course. I would fix the first problem first.

Agreed. Concurrent improvements are a good thing, however. But I can't keep throwing money at finding out what is wrong with my bike. I spent about 1500 already this year to check my valve clearances (result - "within spec"), intake valve vacuum (result - "perfect"), changed thermostat (bike was taking what seemed a long time to warm up... result - original thermostat working fine, no visible chipping of paint inside the hoses at the connections, which is a reported issue). I suppose if the bike is running rich, it could indeed take longer to warm up because of that.

How invasive and difficult is it to remove the O2 sensors....? A visual check could display if one or both are carboned up more than they should be... perhaps...?? I notice there's a LOT of "pre-owned" st1300 o2 sensors on ebay, suggesting to me that they go bad and people replace them a lot. I found Bosch brand heated replacements for a third the price of the OEMs which run 260 cdn$ plus our good ol' sales tax for Justin and his gang...

 

[The Dark Shadow]

How are your tyres and suspension. I have a 2004 with 120,000 km (Australia) and noticed a deterioration in mileage. I've recently replaced the rear shock absorber (with genuine) and noticable improvement. back end was bouncing around a bit and chewing out tyres. Went from 6l/100km to around 5l/100km.

Suspension and tires are in top nick! (Borrowed a limey expression... ;-)

 

[The Dark Shadow]

The porcelain of a very lean-running plug will be bright white instead of off-white, and possibly sparkly.

Thank you!! I'll take photos and post for feedback from those who know more than me.

 

[Bmacleod]

One of the easiest items to check and it is one of the more likely suspects for bad fuel economy is a faulty brake component causing excessive drag on the brakes. I know it was mentioned earlier in this thread but I don't recall if you ever reported back checking it. If you're checking for brake drag you need to check it both at the beginning of a ride and a couple of times intermittently during the ride. You may have responded, but at seven pages long it's easier to just ask.
As far as oxygen sensors on eBay, I don't think that's a gamble I would take. If you're talking about used ones, that would be the same as buying used spark plugs. They are likely out of wrecked bikes so you have no idea what condition they're in. If you're talking about new ones I would think eBay would be the last place you'd want to buy a new oxygen sensor. In my experience, I have seen many reports of people replacing oxygen sensors on vehicles, even with new aftermarket ones from a reputable brand that caused a drop in performance or economy. In some instances people have wasted money and ended up going back to the factory OEM sensors and it fixed their problem. O2 sensors just seem to be too finicky. Also, if you were going to get fake knock off sensors, I would think eBay would be the place you're going to get them. That's just my .

 

[The Dark Shadow]

One of the easiest items to check and it is one of the more likely suspects for bad fuel economy is a faulty brake component causing excessive drag on the brakes. I know it was mentioned earlier in this thread but I don't recall if you ever reported back checking it. If you're checking for brake drag you need to check it both at the beginning of a ride and a couple of times intermittently during the ride. You may have responded, but at seven pages long it's easier to just ask.
As far as oxygen sensors on eBay, I don't think that's a gamble I would take. If you're talking about used ones, that would be the same as buying used spark plugs. They are likely out of wrecked bikes so you have no idea what condition they're in. If you're talking about new ones I would think eBay would be the last place you'd want to buy a new oxygen sensor. In my experience, I have seen many reports of people replacing oxygen sensors on vehicles, even with new aftermarket ones from a reputable brand that caused a drop in performance or economy. In some instances people have wasted money and ended up going back to the factory OEM sensors and it fixed their problem. O2 sensors just seem to be too finicky. Also, if you were going to get fake knock off sensors, I would think eBay would be the place you're going to get them. That's just my .

Thanks mate! Brakes were checked and assessed to be fine by 3 people - 2 pros and one friend who knows his **** really well. I wasn't suggesting purchasing used o2 sensors; rather, I was clumsily trying to point out that since there's a lot of "pre-owned" ones on ebay, it is likely a component that has a considerable failure rate (or people are stabbing in the dark trying to replace them while chasing down their engine troubles).

 

[The Dark Shadow]

Here's a pic of the plugs...

What does this tell you engine gurus...?? I am nothing but a grasshopper... Perhaps a fairly smart grasshopper, but still I'm nothing but a grasshopper.

Seems to me that the parts near the electrodes are clean, but I wonder why so much oil/wet-carbon buildup around the outer rim...

 

[Slydynbye]

I'm no Guru but those look fine, except the first pic is too blurry to see properly.
You might inspect to make sure the the tiny iridium tips are still there, Gap will tell if major bits are missing.

 

[Andrew Shadow]

To get to 20km/l I need to be driving 90kph on flats... Exact same both St1300's... Until I see it, I won't believe that these things get anything approaching good fuel economy. Over 90kph and fuel economy starts to drop... 120kph is pathetic gas mileage...

As I have written previously, I have logged every single tank of fuel that has run through this motorcycle since new, so I know exactly what my minimum, maximum, and average fuel consumption is as well as everything in between. The calculated average fuel consumption, which is the only reliable metric for a discussion comparing fuel consumption, for the entire distance that this motorcycle has traveled since new is 19.65 Km/l.
You can do the math yourself if you like. This motorcycle has traveled a total of 120,438 KM consuming 6128.83 litres of fuel to do so.
There is something that is not making sense, at least to me, with your fuel consumption numbers that needs to be sorted out.

My result naturally will be a little higher or lower than others as there are so many variables. I doubt that I am achieving considerably better numbers than every other ST1300 rider however, as I can see no reason why that would be as there is nothing special about my ST1300 or the way that I ride it. I think that most people would report considerably better fuel efficiency than what you report. You are distrustful of my numbers, so launch a thread asking people to report their average fuel consumption to get a larger sample. Keep in mind that, when comparing fuel consumption with others, different people are using different units-of-measure depending on where they live. i.e. Stating XX MP/Imperial gallon is a vastly different measure and result than XX MP/US gallon, and the poster does not always state which unit-of-measure was used.

An aside that isn't really relevant to this discussion but I thought I would add it as a reference;
My on-board fuel consumption meter average is reset at the beginning of each riding season and is not touched until the end of the riding season. At the end of each riding season it has always displayed an average fuel consumption of 19.X Km/L- always within a few tenths of what my calculated average is.

 

[Chris09]

I get about 34 goofing around and 44 mpg [US] just about at best and I'm pretty sure everything is good on mine; very little rear disc heat, zero front disc heat, bearings cool, drive assy warm. 40 odd k / 25,000 miles. At 120 k the engine is about 4,000 [?] rpm, it's not a Corolla. If your brakes are dragging you're gonna get off the bike and put your hand on the rear disc and feel heat.