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?

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Suzuki AC 50 -78 owned from 83 to 84
Kawasaki Kh 100 Es 81 owned from 84 to 86
Honda Transalp Xlv 600 -97 owned from 01 to 05
Honda Nx 650 Dominator -98 owned from 07 to 10
Triumph Tiger 955 i -01 owned from 10 to 13
Yamaha XT660Z Tenere ABS -11 owned from 2013 and present bike.
Honda Crf250L -12 my bike in Thailand.

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.

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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.

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Simon

Brighton, UK

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.

__________________
Suzuki AC 50 -78 owned from 83 to 84
Kawasaki Kh 100 Es 81 owned from 84 to 86
Honda Transalp Xlv 600 -97 owned from 01 to 05
Honda Nx 650 Dominator -98 owned from 07 to 10
Triumph Tiger 955 i -01 owned from 10 to 13
Yamaha XT660Z Tenere ABS -11 owned from 2013 and present bike.
Honda Crf250L -12 my bike in Thailand.

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...

__________________
Suzuki AC 50 -78 owned from 83 to 84
Kawasaki Kh 100 Es 81 owned from 84 to 86
Honda Transalp Xlv 600 -97 owned from 01 to 05
Honda Nx 650 Dominator -98 owned from 07 to 10
Triumph Tiger 955 i -01 owned from 10 to 13
Yamaha XT660Z Tenere ABS -11 owned from 2013 and present bike.
Honda Crf250L -12 my bike in Thailand.

If the mod was set up at 15-18C and it's now 40C , 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!

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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....

__________________
Suzuki AC 50 -78 owned from 83 to 84
Kawasaki Kh 100 Es 81 owned from 84 to 86
Honda Transalp Xlv 600 -97 owned from 01 to 05
Honda Nx 650 Dominator -98 owned from 07 to 10
Triumph Tiger 955 i -01 owned from 10 to 13
Yamaha XT660Z Tenere ABS -11 owned from 2013 and present bike.
Honda Crf250L -12 my bike in Thailand.

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!

__________________
Suzuki AC 50 -78 owned from 83 to 84
Kawasaki Kh 100 Es 81 owned from 84 to 86
Honda Transalp Xlv 600 -97 owned from 01 to 05
Honda Nx 650 Dominator -98 owned from 07 to 10
Triumph Tiger 955 i -01 owned from 10 to 13
Yamaha XT660Z Tenere ABS -11 owned from 2013 and present bike.
Honda Crf250L -12 my bike in Thailand.

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.

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