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.