Fuel economy is terrible!!

The Dark Shadow said:
Damn... The BEST I can get it 15.6 km/l. A lot more trips to the fueling station...

I just read in a FB group one ST owner stating his thermostat was stuck open, even though there was no code showing nor did the 3 bar temp gauge display anything but normal behaviour. I'm going to have to consider this possibility further.

My 2014 is not a police version. They kept putting bikes out of the factory assembled from previously manufactured parts, as I am told. Mine has slightly different clutch and brake levers than my previous 2005 model.

No faults stored. (Had it checked last week.)

For whatever reason and I know not, my odometer reads close to bang on, and my speedo is bang on! (I know! Ask my local policeman... haha!!!)

Brakes have been checked and are "normal" and "regular". Although I want to check the double disks on the front again in case they are pulling a bit.

BTW, what state/province/country and what elevation are you in...? I read that altitude and heat make a big difference on mileage for this bike.
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Mine had a thermostat stuck open when I bought it. It was very slow to warm, but would maintain 3 bars if the ambient temperature was anything above 15 degrees Celsius, so it was not obvious to me as I ride in the fair weather mostly. I don't recall for certain, but I believe my fuel economy was poor during this period. It was diagnosed by others when I posted to the Coldest Ride several years ago as I had the temperature drop off while riding in the cold (don't recommend). It's an easy enough fix and good time to clean out the radiator and overflow bottle.

Best of luck, my bet is now on that as the source of the problem.
 
Mikedo said:
Mine had a thermostat stuck open when I bought it. It was very slow to warm, but would maintain 3 bars if the ambient temperature was anything above 15 degrees Celsius, so it was not obvious to me as I ride in the fair weather mostly. I don't recall for certain, but I believe my fuel economy was poor during this period. It was diagnosed by others when I posted to the Coldest Ride several years ago as I had the temperature drop off while riding in the cold (don't recommend). It's an easy enough fix and good time to clean out the radiator and overflow bottle.

Best of luck, my bet is now on that as the source of the problem.
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Thanks! Appreciated!!
 
Mellow said:
Most of the time a stuck t-stat will only show when you are in lower ambient temps as the radiator is free flowing and keeping the coolant at a lower temp. When it warms up a bit - outside temps - it will get to 3 bars and the fans will kick on keeping it at 3 bars and the fans keep up as the system is designed to work in those conditions.
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I often drive in 5°C weather. If anything, I've wondered if my bike isn't taking a bit too long to warm up. So when the thermostat is stuck open, what does it do to the radiator fluid? Does it pump it faster, or is it passive convection that circulates the fluid resulting in more fluid circulating and coming because the thermostat is open...?

Thanks eh!
 
Andrew Shadow said:
Montreal, Quebec. Mostly below 1,000 feet elevation locally and when I am not traveling.

Based on your responses, thermostat and/or dragging brakes.
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I'm likely heading up your way soon (on the bike of course). I lived in Montreal 1991-1993. Drove north to the mountains a few times by car. Must be some good motorbiking mountain roads there, n'est pas?
 
The Dark Shadow said:
So when the thermostat is stuck open, what does it do to the radiator fluid? Does it pump it faster, or is it passive convection that circulates the fluid resulting in more fluid circulating and coming because the thermostat is open...?

Thanks eh!
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When a thermostat is stuck open, it takes longer for the engine to heat up, and bringing the coolant to operating temperature. As the coolant temperature rises, the fuel mixture gets more lean, less fuel, until the fuel mixture is at its optimum setting. The coolant would be circulating before its supposed to with an already open thermostat, trying to cool the engine which is why it takes longer to get to 3 bars,if ever. The whole time your engine isn't at operating temperature, you're using more fuel. Fuel injected engines rely on engine coolant feedback to alter the air to fuel ratio.
Comprends tu monsieur? :)
PS.....I also lived in Montreal back in 1968 till 1973 when we moved to NB when I was five.
 
^---what he said.. also, when you start moving forward that cool air is keeping your coolant at a lower than optimum temp.
 
When I got my 2005, it was getting around 35 mpg and had a stuck thermostat. The temp gauge would immediately go to three bars when cold starting. I replaced the thermostat and now get low to mid 40s. With a stuck thermostat, the engine never gets to the proper operating temperature which causes the poor mileage.
 
RobbieAG said:
When I got my 2005, it was getting around 35 mpg and had a stuck thermostat. The temp gauge would immediately go to three bars when cold starting. I replaced the thermostat and now get low to mid 40s. With a stuck thermostat, the engine never gets to the proper operating temperature which causes the poor mileage.
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I got my 2nd ST in May 2022 and it had a stuck open thermostat.
I just changed my thermostat last month and I am noticing better gas mileage.
 
Kevcules said:
When a thermostat is stuck open, it takes longer for the engine to heat up, and bringing the coolant to operating temperature. As the coolant temperature rises, the fuel mixture gets more lean, less fuel, until the fuel mixture is at its optimum setting. The coolant would be circulating before its supposed to with an already open thermostat, trying to cool the engine which is why it takes longer to get to 3 bars,if ever. The whole time your engine isn't at operating temperature, you're using more fuel. Fuel injected engines rely on engine coolant feedback to alter the air to fuel ratio.
Comprends tu monsieur? :)
PS.....I also lived in Montreal back in 1968 till 1973 when we moved to NB when I was five.
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Oui. Je comprend.

But what circulates the coolant - a pump or passive convection. I know the fan blows (sucks??) air past the radiator to supply additional coooling when necessary.
 
The Dark Shadow said:
Oui. Je comprend.

But what circulates the coolant - a pump or passive convection. I know the fan blows (sucks??) air past the radiator to supply additional coooling when necessary.
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A coolant pump at the front of the engine.
The cooling fans are electrically operated and temperature controlled and suck air through the radiator fins from front to back.
 
Andrew Shadow said:
A coolant pump at the front of the engine.
The cooling fans are electrically operated and temperature controlled and suck air through the radiator fins from front to back.
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That's what I was guessing. Thanks for the confirmation. Hence, logically a motorbike with this problem would tend to run richer in a cooler ambient temperature than in a hot hot environment (20 compared to 40°C for example), so some people with stuck thermostats in hot places may not notice am issue as much as me in cool Nova Scotia...
 
So it took approx 2min45sec to get to 1 bar, 3:15 to 2 bars, 5:00min to get to 3 bars. At ambient temperature 16°C.

At cold idle of 2000rpm.
 
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