Increased fuel consumption
 

Hi folks

My Z has after the last big service with valve adjustment experienced increased fuel consumption. Its not a whole lot, I have figured it out to be around 10 %, but still - there is definitively a change in fuel consumption. I noticed this after the service but the bike wasnt used much the last two months before service so something might have happend at that time?

My bike is 2011 Z, it has LeoVince pipes, DNA airfilter, Kev both mods (fuel and O2) I run 15/48 sprockets.

Before service the fuel consumption was always very near 25 km on one litre which is approx 71 mpg. Of course if ridden very fast on highways or slow on bad roads/dirt roads the consuption would increase a little. But with my riding style and not too drastic roads it was really an easy task to figure out this. It was almost always very near this figure.

After that service the consumption is around 22-23 km pr one litre or 63-64 mpg. And I havent changed riding style and there isnt anything else that comes to my mind that can cause this. The bike has done + 70 k km now. The engine and the bike itself feels exactly as strong as before and rides exactly like before as far as I notice.

At the last service the garage said the valves were well within specs so they just adjusted them a tiny bit. I also had new tyres fitted and I have also some extra headlights mounted, but they are quite small in size and cannot explain a 10 % increased fuel use. New rear wheel bearings was mounted also.

Both wheels seems to turn round ok, air pressue in tyres checked every second day of riding and are always near the specs 40 PSI rear and 35 front. I ride with a heavy loaded overland rigged bike. Air filter was cleaned and lubed when serviced and I have checked it later and it seems fine. Chain is lubed every second day of riding and adjusted once (it was too tight out from service)

What could cause the - maybe not remarkably dramatic increase in fuel consumption, but still quite noticable change? Any ideas anyone?

To maintain a given A/F ratio the Kev fuelling mod needs to be turned down a little in the hotter months of the year, particularly if ambient goes much above 25C. For a given setting, say 5 o'clock, the hotter it gets outside past 25C, the richer the A/F ratio will become. The same works in reverse; the colder it gets the weaker it gets, so you need to increase the setting slightly.

Could it be you're increased fuel consumption is related to the better/warmer weather? All depends on at what the baseline ambient temperature was when you set your fuelling mod up originally.

71mpg is very good fuel consumption to start with, as is 64mpg

I had to ride mine like a nun to get over 64mpg - I average 55mpg.

I was also thinking about the hot weather could have anything to say on the fuel consumption. I started out on this leg of my long journey from northern Thailand where it was up to more than 40 degrees and now here in Malaysia where I am now its a few degrees less but more humid.
Anyhow - I did a few internet searches and most of them said fuel consumption should normally go down in hot weather.

The Kev mod was set up in late summer 2013 in Norway so it wasnt at all this kind of temprature, maybe 15-18 degrees daytime.

Anyhow - I will try to twist the little knob down a bit and see if that helps.

Thanks Pleiades, as always you have a sensible answer.

When I was riding with stock gearing and before adding Kev mod, DNA filter and other farkles I averaged 80 mpg on a long distance trip in Scandinavia. Low speedlimits there though...

If the mod was set up at 15-18C and it's now 40C :emoticons:, you're definitely going to need to turn it back at least a couple of positions I'd say. All Kev's guideline settings are based on a 25C ambient - you're getting on for nearly double that!

i guess you have to do more detective work!
the engine uses a lot of fuel while warming up so in colder/ winter weather consumption goes up perhaps 10%perhaps more.


what tires did you put on at the service (they can affect fuel consumption).
the CO setting might have been changed which can also contribute.
did you put in an different engine oil (Ihave experienced about 10% improved fuel consumption by using premium synthetic)
71 is very good but not surprising if your riding style is gently and you don't spend much time in traffic jams and at red traffic lights

About hot weather versus cold weather - I read several places and posted about it earlier in the thread. Hot weather should indeed lower the fuel consumption - so that my bike got increased fuel consuption would certainly be strange. And weather didnt change that much, from 30-35 to 38-42.

I changed tyres from Heidenau K60 to Pirelli Mt60 and the new tyres are less knobby and softer than the Heidenaus. Anyhow it should not under any circumstances affect fuel consum in that way.

Oil used is premium synthetic as it was before - changed at the same garage so that shouldnt be the problem.

But - I think Pleiades thoughts about the Kev fuel mod settings was right. I had it on approx 5 oclock and then after his advice turned it down to around two. And I have now got noticable lower fuel consumption. First tank after I changed fuel mod setting I was at 450 km when reserve light kicked in, which indicates around 70 mpg. That is more as it used to be before.

Although there are a couple of other factors that needs to be mentioned. The previous measurements was in Malaysia where I had usually had a speed of approx 90-100 km/h and was running 95 RON gasoline. I then changed fuel mod setting and moved over to Indonesia where the average speed is only 50-60 and even less due to very heavy and tight traffic and the other thing here is that the normal gasoline here - government subsidised - is 88 octane.
One factor that should increase fuel consum ans one factor that should decrease it....makes it even maybe?

Anyhow - I think Pleiades advise was the right although I still need to check it out further ahead. So thanks to Pleiades again for another proper advice.... :thumbsup[1]:

Increased fuel consumption again

Hello guys

I am now in Australia on my long trip. Took off from Darwin two weeks ago and are riding anti clockwise around Oz.Have done The Gibb River Road. For the moment near Port Hedland.

The Tenere became better after following Pleiades advise about turning back the knop on Kevs mod. I turned it back from 5 to 2. And fuel consumption was almost back to normal through Indonesia - although hard to say exactly due to bad fuel and low average speed/chaotic traffic.z

However here in Australia the fuel consumption is as high as never before. I can get just around 20 kms pr liter. Thats almost 20 % more than before! I have gone down one tooth on the back sprocket and are running 47 now. So that should have helped. New tyres and right pressure and cleaned airfilter before I took off so that shouldnt be the problem. Have turned the knobon the Kev mod back to 12 now since its very hot here - it has been between 32 and 41 so far.

I am not riding hard - just 90-100 on the highway so no excess speeding. Bike is carrying approx the same weight as before.

Anyone that can give me any advise?

If the Kev mod is set at low tempratures - is there any way to reset it so that it can be better adjusted to the high tempratures in Australia?

I had the error code 22 (air intake temprature sensor) appearing on and off for a while and definetively on after the corrugations on Gibb River Road - but I have fixed that lose cable now. It seemed however that the bike got better fuel consumption while the air intake sensor was not working. The Ecu sets automatically to a temprature of 20 degrees if this is not working....

The bike is running smooth and normal so it doesnt seem to be ny problems that way. Its a while since I had the valves done - around 23 k kms - could it be that valves are not right? I will have the valves done when in Perth.

Any suggestions and advise appriciated!

The high temperatures may have something to do with it? Although only very small individually, the differences between riding in 35C hot and 15C temperature climates all adds up:

• Tyres for create more rolling resistance when hot.
  
• Thermal expansion of petrol; you get less KJ of energy per litre in a hot climate than you do in a cold one. Won't make a massive difference, but a difference none the less!
  
• The XT doesn't have a fuel temperature sensor in the fuel rail, so cannot compensate for warmer fuel being delivered from the tank. It is metered by volume, not mass/energy.
  
• Loss of fuel through evaporation and/or expansion from the tank as it's vented to atmosphere. It has come to light in another thread recently that the ABS Ten, due to the shape of it's tank and different breather to the standard bike, can spill fuel out of the breather hose if left in direct sunshine for any length of time even with a part filled tank.
  
• Air is less dense, and although the bike's sensors (MAP/AIT) compensate to a degree, it'll still make a difference.
  
• The fan will operate more often, putting additional load on the alternator and therefore the engine. Again only a very tiny increase in drag, but added to everything else above will compound matters, as will the fact that resistance in all the bike's electrical circuits will increase with temperature!

What fuel are you putting in it at the moment? 91RON, 95RON, 98RON, E5, E10? It all makes a slight difference to economy, especially the ethanol content.

Thanks for answer Pleiades. All of the reasons you mention make a bit of sense.

Although I have been riding in almost same conditions before for example in Kazakhstan and in SE-Asia. And although somehow variable fuel consumption in those places too the bike have never been using this much.

Have to add that the last 2-3 tanks the fuel consumption have been slightly better as I have been averaging 22,2 and 23,1 km pr liter. Strangely as the conditions are the same and my riding style and speed are the same.

The breather hose in the tank do spill out fuel if the tank is filled up completely just after riding and when the engine is hot. I have never noticed that fuel is spilled during riding though...is that reall so that this can happen? How to notice/observere this?

Compared to SE-Asia the fan isnt kickin in much here in Oz. In SE-Asia, especiallyIndonesia where the average speed was 40-50 kms/h it was running more ir less all the time. Here in Oz its very rarely running, so thats not a good explanation.

Can engine temprature have something to say for fuel consumption? I changed coolant in Darwin before starting the Australian leg and used the do called "engine ice". Its supposed to reduce the engine temprature. Although - it must be rather bad stuff as it has been boiling a ccouple of times the last days.

It will be interesting do see ifits any change after the 100 000 kms service in Perth.

This is interesting. "Engine Ice" I believe is similar to "Water Wetter" and is a corrosion inhibitor and water pump lubrication additive, and not an antifreeze; it contains no ethylene glycol. It is disign for race bike/cars where ethylene glycol coolants are not allowed due to their toxicity. Effectively with this in the cooling system you are running pure water.

Water has a much lower boiling point than a water/glycol mix, which may explain your boiling issues. Pure water boils at 109C at 8psi (typical in a pressurised cooling system), whereas as 50% glycol/water mix will boil at 120C at 8psi. The XT's fan cuts in at 102C and the temperature warning light comes on at 110C, which is after a pure water mix will have started boiling! The cooling system on the XT is designed to and will only work properly with at least a 33% glycol mix.

The reason they claim "cooler running" with Engine Ice or Water Wetter is that pure water has a higher specific heat capacity (better at storing and transfering heat energy) than a glycol mix. In other words, with Engine Ice in the cooling system it will cool more efficiently within it's operating range of 4C to 100C, but doesn't work above 100C as it starts to boil at atmospheric pressure. A glycol mix, while slightly less efficient at storing/transfering heat at 50% has an operating range of -30C to 110C at atmospheric pressure.

Engine Ice/Water Wetter will also slow down warm up times and can cause the thermostat to delay opening, which mens the engine is running outside it's temperature rang efor peak efficiency? As I mentioned, the XT cooling system components and fuel injection parameters are match to the properties of a glycol-based coolant.

I think you may well notice a difference going back to standard coolant...

Thanks again Pleiades for your reply and sharing your very accurate knowledge about this subject.
Shouldnt have listened to those Aussie guys in Darwin then. Really strange that they didnt know better by the way....
Will definetively go back to normal coolant again asap.

Hi Snakeboy, I live in Oz on the east coast, ride a 2012 z, have 15/48 gearing, use 95ron , have both kev mods,air filter, leo vince pipes, etc. and riding on a long trip averaging 100kph get almost exactly 400kms before the reserve starts flashing. Maybe it's the aussie fuel that makes the difference. Just a thought.
Brad

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Is the aussie fuel any different than other fuel?

I have used 95 fuel mostly but some of the more remote places between Darwin and Perth have only 91, so have had that 3-4 times.

Anyhow - when you say youre getting 400 kms before reserve starts, is those 400 km on the ODO/trip on your bike or on GPS?

If youre riding with 15/48 your ODO/trip will be faaaar out. More than 10 % I think....

Now my bike has definetively changed to the worse when it comes to fuel consumption. I have now had it served - 100 000 kms - valves checked and fine within specs, new oil and filter, newsparkplug, cleaned airfilter etc etc. Had a run of 1500 kms and more than 3 tanks now and the fuel consumption is around 20 kms of one litre. I have been riding in outside tempratures of 18-25 so not that hot as before.
I even changed rear sprocket at 90 k kms and went down one tooth to 47. Still this increased fuel consumption.

Its such a pity and a shame. This was one of the best features of this bike, especially for my use as an overlander bike - namely the relatively low fuel consumption and thus long range. Now the Tenere uses more fuel than my last bike a Triumph Tiger 955i - if I rode it around 90 kms an hour with panniers etc. And that bike which was a lot heavier and had more than twice the power of the Tenere. The old carburated and heavier 600 Transalp that I had long time ago was also using less fuel.

The boiling coolant issue I had was because I had a radiator cap that wasnt working. Its changed now of course but that had nothing to do with high fuel consumption.

If one google "increased fuel consumption" one can find answers such as bad/sluggish oxygen sensor, defective coolant sensor, lower compression, defective thermostat (mine works ok according to the garage who performed 100 k kms service) or can one of the Kev mods fail in a way that increases the fuel consumption?

Brakes are not hanging, tyres are new and have correct pressure.

To be more precise - before the service I had done at 72 k kms and add that the bike was very little in use the two months before that service I got 24-25 kms pr litre of fuel. Best recorded tank was 615 kms and filled up 22,7 litre which gives more than 27 kms a litre.
Nowadays I seem to get only around 20-21 kms pr litre. Had one tank that I got only 19 kms pr litre.

I am overlanding and the bike is loaded, but it has been like that all the way. I am riding at 90-95 kms an hour maximum, sometimes slower. No hard throttling no hard accelrations. Gentle and careful riding.

Any ideas guys?

Yes you're right. My readings are from my ODO and I know that at 100kph my speedo reads 110kph.
So, I get 400 k's before reserve according to my inaccurate ODO. Or 500 k's for 23 litres equating to 21.74 kpl on a recent run. So factor in the difference of 10% or divide by 11 and I'm really only getting 19.77 kpl, similar or worse than you. And I thought I was getting great economy.
Anyway I wouldnt be too concerned, my mates KTM640 Adventure and Aprilia 650 Pegaso get less economy than my tenna. Maybe it's aussie fuel after all? Safe travels.

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Yeas the fuel consume you describe now is similar to what I have experienced since a while back. Problem is that I got a much lesser fuel consumption all the time from I bought the bike - it had 13 k kms on the ODO - up until 72 k kms.
And the mystery is I havent changed anything since that can explaine this increased fuel consumption. My riding style is the same, my speed is the same, the weight on the bike is the same, even changed the rear sprocket to one tooth less but without any noticeable difference.

Before 72 k kms - 24-25 kms pr litre, after 20-21 kms pr litre. Very strange indeed! And very annoying here in Australia as there are so vast distances here and long range would have been gokd worth.

There is another thread about fuel consumption where a Ten owner says he had issues with the sparkplug and that with a irridium spark plug his Ten is back to that bikes normal 4,2 litres pr 100 kms - which is approx 24 kms pr litre. So there certainly are others that gets as many kms out of each litre of fuel as I (used) to do.
By the way - maybe I should check if there is a irridium spark plug on the bike???

Thanks for your safe travels wish by the way. Heading over the Nullabors later this week.....

Where are you now, are you in Perth?? Can't say I have a solution but if you want to do any work, service, adjust etc before you head east let me know as you are welcome to my workshop and tools.
Matt.

Yeas I am in Perth right now. And thanks so much for the offer - much appriciated. However I am well housed and fed here in Perth so no worries about that.

I would have liked to adjust down the fuel consumption a bit though.....:eusa_think:

my 660 R returns between 62 ~68 mpg (uk gal) depending on the season and riding in or out of town.
on the open road I tend to stick to 65~80 mpg. I think the Z is slightly heavier than the R.

I think the O2 sensor signal is bypassed once the rpm goes past a certain speed after which the fuelling follows a preset map. But I take it kev's mod you have eliminates the O2 sensor anyway.

Over here and the US ethanol is added to petrol. IN the uk is 5% and it increases the fuel consumptions ( I won't go into other non desirables it does). Maybe the fuel sold wherever you are has a high ethanol content.

I don't think the Z has a knock sensor so lower octane fuel will also affect the fuel consumption

How fast do you ride it and what revs do you cruise at?

71 mpg is great - I only average 55 mpg (UK)

Sadly I dont get that 71 mpg anymore. Those happy days are definetively long gone. Nowadays I am on 20-21 kms pr litre which is approx 58-60 mpg.

I run 15/47 sprockets for the moment and average speed on highway 90-95 km/h. Which is around 4000 rpm. 92,5 km/h is 4000 rpm. Bike is used for overlanding and are quite loaded.

What are other people's experiences and how are their bikes setup?

If I stick to around 5,000 revs (80 mph) on stock gearing I get 53 mpg, if I pootle about at 55 mph (I think that's about 3,000 revs) I get 60+mpg.

That's loaded on a long trip.

My fuel records (I have an app on my phone) over the two years I have had the bike including its transition from uber-stock to modified show I average 55mpg.

I have stock gearing, PCV with Autotune on stock AFR maps, stock exhaust with cat removed, DNA S2 (no snorkel) and blocked AIS

MPG is UK gallons (4.54 litres per gallon)

I keep on coming back to this thread. I cant simply accept the fact that my bike suddenly started to use approx 20 % more fuel.

Before around 25 kms pr liter, nowadays approx 20 kms to a liter. I can force it up to 22-23 kms pr liter if riding 70-75 k/h on a good day - but how fun is that?

I have just been 10 weeks in New Zealand where I rode 12 000 kms on a Suzuki Dr 650, an old school carburated and air cooled bike and loaded up with gear and riding 90-95 km/h (my normal riding pace) I got 24-25 kms pr liter fuel on that bike.
I rented a Suzuki V-strom 650 adv a while ago and averaged 26-28 kms pr liter riding with a pillion on that bike. I have a mate thats got a Kawasaki Versys 650 which he averages 26-28 kms pr liter. And that bloody Tenere sucks in a liter every 20 kms even riding relaxed at 90-95 km/h. Just dont make no sense at all.

Both are same cc bikes - just two cylindered and a good bit more power in them. Why this enormous difference in fuel consumption???

I have had my Tenere tested in a Yamaha workshop - although probably not the best workshop in the world. They couldnt connect it to the computer programme but used a tool to measure all sencors - and all seem fine. Measured the exhaust and it was very near spot on. Couldnt do a compression test because the equipment they had didnt work but bike has the same power as before so I would t expect it to be something wrong with that.

Yesterday I disconnected the Kev O2 mod and rode 350 km without it but no difference in fuel consumption.

I had a bit of wheel alignment problem a while a go - which I might thought has been going on for quite some time. But even that didnt effect the fuel consumption and no difference when I got the wheel alignment ok.

Tyre pressure is fine, wheel alignment are fine, brakes are not hanging on, valves checked and fine, new chain and sprockets, new tyres, new oil - ****ty milage!

A quick sumup - on a long overland trip Europe to Australia I averaged approx 25 kms pr liter until I left Thailand. The bike stood two months without much use in very hot weather and it then got a full service and I headed off into Malaysia, Indonesia and now I have been some months in Australia. After I left Thailand the milage went from approx 25 kms pr liter to 20 kms pr liter. At first I thought I was riding faster than usual, then I blamed it on low octan fuel in Indonesia etc etc - but the truth is the fuel consumption went approx 20 % up. In the meantime I have gone down one tooth on the rear sprocket - without any noticeable difference in milage. I try to use 95 octan fuel when possible as this is the recommended fuel quality from Yamaha dealer back in Norway but sometimes I have been forced to put in both 91 and 98. Octane numbers does influence fuel consumption a bit, lower octane number will give more fuel consumption and higher will give less consumption - so the bike reacts to that.

I ride slow and easy and on straight highways Im usually inwtween 90-100 km/h. On bad roads/dirt roads and narrow and winding roads of course much slower. No way I ride 120-130 km/h = 75-80 miles/h.


Tenere 2011 ABS model. With Leo Vince pipes, KNA airfilter and both O2 and fuel sensors from Kev. Now sround 110 k kms on the clock.
Except from that the bike actually runs fine - so Im just very confused???

The Yamaha workshop said the bile is old, carbon is building up in the injection system and elsewhere so I have to expect this. But this didnt happend gradually - it happend overnight. It uses very little oil - from Perth to Melbourne approx 4000 kms - approx 0,4 liters.

Any suggestions where to look next guys?

Another strange thing - I tried to connect the Kev O2 mod again today but two of the wires in the connection were loose and the way they were connected they couldnt be attached again. So I tried to start up the bike jut to check - and it started and no warning light in the dash. I then disconnected the whole thing again and did not connect the O2 sensor - started up the bike. It run normal and no warning light in the dash. Isnt that strange? No warning light at all even though the O2 sensor was disconnected?

I understand less and less...

Same problem here, my bike xt660x 2005. 13000 km.
Leovinci, stage 1 airfilter, power commander v.
I drive 160km with 9,5litre fuel, thats almost 1 litre on 17km.
Normal traffic, ridden hard and soft, high and low speeds.