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

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.

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.

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.

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

Sent from my SM-G920I using Tapatalk

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....

__________________
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.