Why is my FZS600 consuming almost 10 l\100km (28mpg)??

[Feral Kid]

Hi, I recently checked how much petrol my Fazer is using and I was quite shocked; almost 10 l/100km (28mpg) I am riding it most of the time in a city, but usually at the slow to medium pace, avoiding going to very high revs etc.
The only problem I'm aware of is missing seal between the exhaust pipe and the muffler. Could it be a reason why it's using so much petrol?

[Nobby the Bastard]

[Copycat73]

[Feral Kid]

I haven't fixed it, because it sounds way better than with it and it's not very loud. But I guess I willl have to fix it . And replace the air filter. Thanks for advice. I will let you know whether it helped

[c_dug]

Mine does around 145 miles to fuel light pretty consistently, I'm quite right hand heavy and the bike is -2 on the front sprocket so they shouldnt really get much worse than that.
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[Teflon-Mike]

First thing I would check is your maths.
Then your measurements....
- What level do you fill to?
- Do you use the pump readings?
- Over how many fills have you averaged measurements?
Have you for eg, done a first fill, and then a last fill, and added fuel unused to fuel used over short mileage?

Of all likely errors, this is the one that's most likely, and where simple conversion from liters to gallons, or Km to miles, is likely to chuck the numbers so wildly out of expected range.

For a 600, 28mpg if true would be pretty dire.

Book for my behemouth VF-thou was about thirty something... If I was a very good boy, I could get around 70 from it, about double the book.... if I wasn't... I could get worse than half! But I had to be a very very bad boy to get it down that low. Round town, commuting about Brum, I rarely managed the book, but the A-Roads 'home' either end, with a little 'enthusiasm' probably saw the average 'drop' to what it gave in the city.

Book says the Seven-Fifty should do about 50; When I bothered to record it, variance was from maybe 40, up to as much as 70 or more. Again depending on type of use, and again, I tended not to get the 'best' numbers about town but 'better' than cross country / 'avin-a-laugh.

I guess the Fazer ought to be in about the same order. AND last few moths, weather's been cold. starting hard, with a lot of time on choke, and certainly in my case, riding off choke still on.

If it's been taking a bit to catch? You could have bee chucking a lot of juice down the pipe on start-up, and if you have been doing shorter journeys, that start-up loss could be quite a bit.

You'd probably have to run it forever on full choke to get genuine numbers that low, though, I'd suspect, so even a sticky choke flap, on ti's own probably would't account for all of it.... But couple that to a bit of measurement vagary? Could be in the right sort of realms.

Could, and likely is a 'compound issue' of a number of different things, and chuck in some old spark plugs, a choked filter, a slightly leaky exhaust, they could all start adding to the tally.

Could be something 'dumb' like a sticking float needle, 'cos alloy carb body contracts more in cold than steel needle, and or rubber 'o-ring' on the end is harder and doesn't 'seal' so well, and fuel is drippng, very slowly from the over-flows over night, if fuel tap not 'off'. Quick check for that one, is to top up on way home; park o the side stand, check level in tank, and see if it's dropped any come morning.

That one is worth checking next after the maths TBH, you wont necessarily see any fuel 'spill' on the floor beneath bike, especially if outside. Drip could be so slow, that even n cold the petrol evaporated without leaving significant 'tell'; it may not be drippng direct on floor, but onto the frame or back of engine, and evaporatg from there, especially if over flow pipes cracked or missing; and even of drops left, easy to be mistaken for dew or rain.

Not sure what sort of fuel tap the Fazer has, but some are notorious for leaking when the vacuum diagphram starts to perish, or mechanism gets old.. if you get level loss over night 'tap on' and still get loss 'tap off' then likely the tap is to blame and fuel possbly leaking out through the diagphram, onto top of engine, rather than from a float bowl over flow.

And very mild 'leak is probably more likely to account for such an aparently dire consumption than an engine fault, that IF it was that bad, it would be like riding with the choke full on, and you'd have cloud of blue smoke fro the exhaust, and probably smell of petrol, and or it would obviously not be running on all four pots, or carburating cleanly, and you'd have flat spots all over the place and bike not willing to rev then clearing its throat ad going crazy, and it would manifest itself i far more pronounced and obvious 'problem' hinting towards carbs.

So start with the maths and the measurement accuracy; get a good accurate measure, and repeat it a few times, compare and average results, see how they fare; max, min, range, and average.

Check 'loss' by depth testing after fill, yap on, and again, for comparison, tap 'off', for obvious leak.

Before pulling anything to bits, and then work from there.
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My Webby'Tef's-tQ, loads of stuff about my bikes, my Land-Rovers, and the stuff I do with them!
Current Bikes:'Honda VF1000F' ;'CB750F2N' ;'CB125TD ( 6 3 of em!)'; 'Montesa Cota 248'. Learner FAQ's:= 'U want to Ride a Motorbike! Where Do U start?'

[A100man]

A long time since I had mine but I think it would do 40 ish around town and closer to 50 at constant m-way limit cruising. I think you would have to be caning it fairly mercilessly to get 28.
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[Polarbear]

I would say, presuming your figures are correct, there is something amiss. My used and abused Fazer hack doesn't approach those sorts of figures however I ride it.
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[Feral Kid]

[A100man]

[Shinigami]

43 sounds normal. I usually get between 145-160 miles per tank before I hit the reserve warning on my '08
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