Is this normal gas mileage?

Re: Is this normal?

Yes, there is something wrong. Your bike even two up ridden hard should not be getting mid 20's mpg US. I think the problem is the mileage sample. Try a few more fillups over time.

To get a good average mpg the bike needs to be ridden quite a distance over a number of tanks of fuel. There are many variables to average out. Weather, seasonal and regional gasoline blends, pump errors, tank fill variations, etc. And forget looking at the instant mpg. It is only a snapshot at one speed at one throttle setting for one moment in time. If you are serious about getting accurate mpg for your vehicles join an app like Fuelly and track your usage over minimum of a few thousand miles. If it's on your phone it only takes a moment to add gas stop information. Fuelly is tracking or has tracked about 100 ST1300s for over a million miles. Mine is in the sample for about 15,000 miles. These bikes get mid to low 40's US miles per gallon. Yes, for example you can ride it in a manner to see close to 60 mpg and another way to see about 25 but calculated mpg over time will likely be close to 42.5 mpg.

Re: Is this normal?

I could tow a boat with my 1100 and get better than 24mpg, something isn't right. Averaging over multiple tanks isn't going to help if its that low to begin with. That low a figure would suggest maybe its running on 2 or 3 cylinders, but he says the bike accelerates well, so that doesn't seem likely unless his idea of hard acceleration is different from mine. Is it possible there's a fuel leak you haven't noticed? I'd expect that to have a strong gasoline smell though, so you'd think it would be obvious. I'd also do a plug check because if its running rich enough for 24mpg you'd think the plugs would show some soot to confirm the rich condition.

+1 on the T-stat to verify its not running too cold.

edit: forgot to mention checking for brake drag, but if its that severe I'd think you'd feel it pushing the bike around.

Re: Is this normal?

Thanks for all of your replies!

Here's what I know:

• When I bought the bike it had an erratic idle when cold and in fact stalled once coming up to a light.
• I cleaned the 5-way T which was full of gunk. I also replaced the K&N air filter with an OEM air filter.
• I have not yet done a TB sync as I cannot find a decent set of sticks locally.
• There is no smell of gas so I'm ruling out a leak. For the moment at least.
• I'm pretty confident it's running on all four cylinders. At idle it's as smooth as an electric motor. It does get a bit 'rough' sounding higher in the rev range, say 5000 and above.

The difference after cleaning the 5-way T was astounding. On a cold start it immediately goes to 1500 rpm. Before it would sometimes go to 1500 rpm other times not. By the time one bar shows on the temp gauge the idle is around 1000 rpm.
It's been cool here, this morning the temp is 10 deg C so the time to reach 1 bar is a bit longer.

I just realized that the photo showed the avg fuel econ from the previous owner as I had not yet figured out how to reset it. But the trip distance of 194.3 kms and fuel fill of 18.75 liters are correct.
I did reset it on my last fill. I'm down to two bars on the gauge it shows 11.0 with a trip distance of 245 kms. I haven't refilled as yet but will update when I do.


The one thing I'm struggling to understand is how the thermostat is a factor in fuel economy if the engine is at normal operating temp.
I'm not a mechanical noob so please bear with me. And none of this is meant to challenge anyone's expertise.

As I understand it the thermostat in an engine is designed to let the engine warm quickly and to keep it at proper operating temp. When the engine is cold it blocks the flow of coolant to the rad to ensure a quicker warm up. It gradually opens as the temp rises to allow coolant to flow through the rad to ensure the engine doesn't overheat.

So far, so good?

I can understand why the thermostat would be suspect if during the course of normal running the temp gauge fluctuated. But mine has never been less than three bars after it's warmed up. I completely understand that warming the engine before putting it under load is important.

I'm not challenging anyone, just trying to understand how the thermostat could play such a big role in fuel economy when according to the temp gauge I have what appears to be an engine running at normal operating temp.

Re: Is this normal?

I was thinking that the ECM reads a resistor to see what temp the engine is at. If it is at anything less than fully warmed up it will enriched the fuel mixture. My gas mileage was down in the mid 30s but it usually reads in the low 40s. The temp gauge always read 3 bars. I changed the t stat and now it is back in the low 40s. Just saying.

Re: Is this normal?

DavidR8 said:

The one thing I'm struggling to understand is how the thermostat is a factor in fuel economy if the engine is at normal operating temp.

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I'm not a 1300 owner, but I'm gonna take a guess, and hopefully someone else can confirm/deny.

I think I get the reason they say to check the time it takes to get to 3 bars when you first start the bike. I'm guessing that 3 bars are illuminated over a very wide temp range, so even if your bike is running cold, you still see 3 bars. Let's say for example that 3 bars are illuminated at 120F. If you know that the bike should warm up to 120F within the first minute, and it doesn't, then perhaps your stat isn't working properly. If it takes 5 minutes to get to 3 bars then maybe your bike is running at 120F continually, but you still see 3 bars. Once it gets to 3 bars you have no more information, it could be running at 120F or 180F, the gauge reads the same. I picked the 120F number randomly, but you get the idea.

Re: Is this normal?

I don't think the thermostat is playing a major role in your mpg but the gauge isn't very informative as to actual coolant temperature. IIRC the third bar represents 150 to 220 degrees F. If it is heating to 150-155 F and holding there instead of going to to an optimal 185-195, it still shows three bars but the ECM could still be slightly enriching the mixture at 150ish. However the usual failure mode is the bike will warm at idle to three bars but when moving air through the radiator it begins to dance between 1 and 2 bars.

Re: Is this normal?

Thanks!
That makes sense to me. Basically it could be running at the low end of the temp range of 3 bars thus allowing some degree of enrichment.

(for what it's worth I just bought a Morgan Carbtune so will do a TB balance as soon as it arrives.)

Re: Is this normal?

I leave my gauge set to "average" and it's parked on 32 MPG. Mostly around town spirited riding.
I have done everything there is to do and I believe it just is what it is. The bike runs very well. I put a lot of time into improving it with temporary results if that's possible.

Re: Is this normal?

JimGregory said:

I leave my gauge set to "average" and it's parked on 32 MPG. Mostly around town spirited riding.
I have done everything there is to do and I believe it just is what it is. The bike runs very well. I put a lot of time into improving it with temporary results if that's possible.

Click to expand...

Thanks Jim. I read your thread with interest earlier today. I'm going to see what a TB sync does and will likely pick up a new thermostat for good measure.

Re: Is this normal?

Is this normal?
NO

mine usually shows 17.7 km/liter
day in day out

my odometer is set to miles... fuel flow does not have that capability

Re: Is this normal?

MDTurley said:

Is this normal?
NO

mine usually shows 17.7 km/liter
day in day out

my odometer is set to miles... fuel flow does not have that capability

Click to expand...

I dream of 17 kms/l !

Re: Is this normal?

DavidR8 said:

I can understand why the thermostat would be suspect if during the course of normal running the temp gauge fluctuated. But mine has never been less than three bars after it's warmed up. I completely understand that warming the engine before putting it under load is important.

I'm not challenging anyone, just trying to understand how the thermostat could play such a big role in fuel economy when according to the temp gauge I have what appears to be an engine running at normal operating temp.

Click to expand...

David, many of us (myself included) had the original OEM thermostat stuck open. It would take longer to warm up and in cooler weather I would actually see the temp gauge drop from three bars to two while riding down the highway. As mentioned, the ECU will enrich the mixture when it sees an engine temp below normal. In my case, my mileage went from 40-42MPG down to the low to mid 30's. I changed the thermostat and all was good. You don't have enough information yet to know whether that may be contributing to your poor mileage but it's definitely something for you to keep an eye on.

Re: Is this normal?

STumped said:

David, many of us (myself included) had the original OEM thermostat stuck open. It would take longer to warm up and in cooler weather I would actually see the temp gauge drop from three bars to two while riding down the highway. As mentioned, the ECU will enrich the mixture when it sees an engine temp below normal. In my case, my mileage went from 40-42MPG down to the low to mid 30's. I changed the thermostat and all was good. You don't have enough information yet to know whether that may be contributing to your poor mileage but it's definitely something for you to keep an eye on.

Click to expand...

Thanks STumped. I agree. I'm going to see if I can pick up a new thermostat today. Likely won't get it installed today though.

Re: Is this normal?

Here David, have a read and see the photos on my post here...
https://www.st-owners.com/forums/showthread.php?158993-Strange-thing-happened-on-the-way-to-a-Honda-dealer&highlight=

Re: Is this normal?

STumped said:

David, many of us (myself included) had the original OEM thermostat stuck open. It would take longer to warm up and in cooler weather I would actually see the temp gauge drop from three bars to two while riding down the highway. As mentioned, the ECU will enrich the mixture when it sees an engine temp below normal. In my case, my mileage went from 40-42MPG down to the low to mid 30's. I changed the thermostat and all was good. You don't have enough information yet to know whether that may be contributing to your poor mileage but it's definitely something for you to keep an eye on.

Click to expand...

Thanks STumped. I agree. I'm going to see if I can pick up a new thermostat today. Likely won't get it installed today though.

Re: Is this normal?

cdnemsguy said:

Here David, have a read and see the photos on my post here...
https://www.st-owners.com/forums/showthread.php?158993-Strange-thing-happened-on-the-way-to-a-Honda-dealer&highlight=

Click to expand...

Thanks, that's very helpful!

Re: Is this normal?

dduelin said:

IIRC the third bar represents 150 to 220 degrees F.

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That's what I was expecting to hear, thanks for the info. Seems like they could have done a much better job of reporting coolant temp to the rider, I guess they just didn't care.

Re: Is this normal?

dwalby said:

That's what I was expecting to hear, thanks for the info. Seems like they could have done a much better job of reporting coolant temp to the rider, I guess they just didn't care.

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The trend in vehicles for about 20 years is like this. I don't really blame Honda as many manufacturers give us gauges like this if they have a gauge at all. My '99 Miata has an "analog" coolant temp gauge with a needle and C N H but in reality "N" spans 165 to 227 degrees. The needle stays in one spot over N until 228 degrees. The oil pressure gauge is the same way. Idiot gauges instead of idiot lights they convey the same information.

Re: Is this normal?

dwalby said:

Seems like they could have done a much better job of reporting coolant temp to the rider, I guess they just didn't care.

Click to expand...

They're damned if they do and they're damned if they don't.

Three bars across the range of the usual ambient to operating temperatures is 40+ degrees per bar, which is more than enough to show when something's wrong with the cooling system. That's a lot more information than you get on bikes that only have a warning light and more than enough to soak in at a glance while you're riding: less than one bar is not warm enough to ride, the tick mark at the center of the scale is normal and the red area at the top is too high.

If they reported the temperature precisely, we'd have three or four threads a year where somebody's freaking out over the fact that the coolant temperature isn't being maintained at exactly 185 when it doesn't work that way.

--Mark

Re: Is this normal?

dduelin said:

The trend in vehicles for about 20 years is like this. I don't really blame Honda as many manufacturers give us gauges like this if they have a gauge at all. My '99 Miata has an "analog" coolant temp gauge with a needle and C N H but in reality "N" spans 165 to 227 degrees. The needle stays in one spot over N until 228 degrees. The oil pressure gauge is the same way. Idiot gauges instead of idiot lights they convey the same information.

Click to expand...

yeah, I agree with cars. I think a lot of them have only had 'hot' idiot lights for years, whereas all the water-cooled bikes I've owned had an analog temp gauge, so I'm thinking more of bikes. Trucks and better cars have had analog gauges but now everybody is going to graphical displays it seems, including bikes.

Blrfl said:

They're damned if they do and they're damned if they don't.

Three bars across the range of the usual ambient to operating temperatures is 40+ degrees per bar, which is more than enough to show when something's wrong with the cooling system. That's a lot more information than you get on bikes that only have a warning light and more than enough to soak in at a glance while you're riding: less than one bar is not warm enough to ride, the tick mark at the center of the scale is normal and the red area at the top is too high.

If they reported the temperature precisely, we'd have three or four threads a year where somebody's freaking out over the fact that the coolant temperature isn't being maintained at exactly 185 when it doesn't work that way.

--Mark

Click to expand...

yeah I get that, and I think you're probably way low with the 3-4 thread estimate. But it would appear the 3rd bar is actually a spread of 70F, not 40F, which seems a bit coarse for my taste. My car has a segmented coolant temp gauge, but its in a semi-circle like the old analog gauges, and has about 12 segments in the display, which is much better and no harder to read at a glance than less segments. When I finally move on from my old ST1100 its going to take a little getting used to digital instrumentation, I've never liked it but I'm not going to get a choice in the matter.