86km to Huntly, and used just under half tank off gas - geeez.

[crystalball]

Now I exspect my 1990 zzr 400 shouldint use that much gas.It runs on 91 as the bike shop said to run it on that.
The last guy I brought it off reakons he ran it off 95 so the first week I used 95 but the bike missed a little bit and tugged like it was hungry for gas.Since I have used 91 those problems have gone. I find its good round town but on the highway it likes to use the gas. mayby its letting to much gas through in the petrol line i don't know.I only really use 5th and 6th gear on the highway so im not reving it all the time.It has a single muzzy exhaust system iv'e heard this also helps on fuel costs.
i'll ask the bike shop next time i'm in.
I know most bikes are meant to be good fuel savers but geeez should last longer than that lol.

[howdamnhard]

I've got a 91' ZZR 600 and am currently getting 18km/l however that is pottering around commutting to work and back (4000rpmish).So I should get around 300plus km/tank(18l). I was told the 400 has the same frame as the 600 hundred so you are lugging around same weight with smaller engine.I sit at 5000rpm in top gear(6th) doing 100km/h.

[crystalball]

Year on highway sits between 6000 and 7000 revs in 6th gear just below 110km. I find in 50km speed zones I like to use 3rd most of the time which puts the revs around 5000. My bike seems too slugish if it sits on 4000 revs. Sometimes I do sit it around 4000 in 4th gear to try save on fuel.

[Max Preload]

Now I expect my 1990 zzr 400 shouldn't use that much gas.

Correct.

It runs on 91 as the bike shop said to run it on that.

That's just so wrong. 95 or higher.

The last guy I brought it off reckons he ran it off 95 so the first week I used 95 but the bike missed a little bit and tugged like it was hungry for gas.

Surging. Sounds like Shell's 95 V-Power.

Since I have used 91 those problems have gone. I find its good round town but on the highway it likes to use the gas. mayby its letting to much gas through in the petrol line.

The carburettors determine the fuel usage, not the petrol line. They do so primarily by regulating fuel level in the float bowls and jet sizes. When was the last time the carburettors were synchronised ('balanced')?

It has a single muzzy exhaust system I've heard this also helps on fuel costs.

If it's properly tuned for it, it would be perhaps little different.

I know most bikes are meant to be good fuel savers but geeez should last longer than that lol.

Are or aren't? Ridden really sedately (like 100km/h all the way from Caltex Bombay to Shell Matamata) my 1100 has returned 60mpg (20km/l) with tank bag, tent & pack on-board.

[FJRider]

Check/clean your air filter... if its dirty, fuel/air ratio gets a little "one sided" and uses more fuel.
Up and down the gears (passing traffic and the like) Heavy braking and then acceleration, both chew into the gas on smaller bikes...
A smooth riding style will save you heaps...

[Tone165]

If you used 9ltrs of juice to go less than 90k's on a 400cc, and you were not towing a 20' caravan....you have a serious problem!

Get theee to a Mechanic asap, and get the bike serviced and tuned...sounds to me that you will recover the cost by the time the next service is due, in saved petrol money!

On fuel (octane) Bikes "can" run on 91 or 98, and in FI bikes the computer will make adjustments to suit on the move. Your bike which is not FI will go best on the fuel it is tuned for, I would advise 95 or 98, mostly cos they are cleaner, but they do have a higher "Calorific value" as well.

Octane is a bit of a red herring term. The main advantage of higher octane is its less prone to "pinking" or detonation in high compression situations (like bike engines)

Higher octane burns smoother when you ride rougher...

91 Octane is where the dregs and tailings are "dumped" and will have different characteristics week to week. Sometimes, 91 octane could be a cocktail that includes avgas (100 octane) that has passed its "use by" date, with added diesel/furnace oil etc.. to bring octane back to 91.

I use 98 myself, but have no prob with 95 if I cant get 98. I would rather not put 91 in the bike...car runs fine on it though!!!!

[homer]

the most harm you will do with low octane fuel is get a little pinking in the engine .
most engines these days and back to early 90s as these are modern engines to , you will find will run perfectly well down to 87 octane.
the thought that a low octane fuel will reduce performance is not quite correct.
search posts on here theres lots of info .
run the bike on what it sounds and runs best on .
before a lot of post in regards to this that ive just posted, i suggest go read your owners manual in the fuel requirements first.

[Max Preload]

the most harm you will do with low octane fuel is get a little pinking in the engine

'Pinking' is such an innocuous and dainty name. Let's call it what it is - detonation - which, if it occurs at high rpm, can quickly destroy the engine and if present at lower rpm will at the very least significantly reduce engine life.

It makes no difference as to whether a bike is fuel injected or otherwise as to whether it will cope better with detonation. I believe you're confused as to the function of a knock sensor - do any bikes actually have knock sensors to retard ignition timing if detonation occurs? I suspect not, since they've only just had closed loop fuel injection in the last couple of years, a feature on cars since the mid-80's.

[xwhatsit]

I don't think octane rating has much to do with using around twice the amount of fuel you should use. P.S. use the lowest octane your engine can cope with without pinking; higher octane fuels burn slower (that's why they are more detonation-resistance) and the octane rating has little to do with the calorific value.

You sure it's not leaking fuel somewhere? That's horrific mileage. Did somebody botch the carbs when they `tuned' it for the aftermarket silencer?

[crystalball]

Well thanks for helping guys. There is no fuel leak as no smell off petrol and cant see petrol anywhere. I had a tuneup few weeks ago the bike runs fine but yes I will be asking the bike workshop that few others have siad to run it on 95. he reakons that this was the cause off the bike not running smoothly.I'll have a look at the air filter as well. Thanks for all your advice i'll be mentioning these ides as well.

[The Pastor]

sounds like a leak mate, or your running it waaaay to rich. (or its tuned to the hilt and puts out a bazillion more hp than stock).

But i still gotta ask, how big is the tank?

[homer]

sounds like a leak mate, or your running it waaaay to rich. (or its tuned to the hilt and puts out a bazillion more hp than stock).

But i still gotta ask, how big is the tank?

thats a good point to , and very possibly is running to rich .
especially if the fuel economy is noticeable in regards to the km your getting .
it could also appear to use a lot of fuel dependant on the size of the tank.

[crystalball]

The tank is huge lol. mind you it cost me $17.60 to fill up from when the fuel light came on. Well after I get other problems sorted lol i'll get it checked out might just need a carb balance and clean, float levels e.t.c air filter clean,( I can do air filter that must be easy) and yes could be runnin rich but dont think it is as I cant smell fuel. No leak tho. but 1st getting rear cush drive in january fitted already paid for the part( to help soften that clunky gear changing the kawaks have lol.) then fork seals replaced in jan as well.

[shafty]

Mate, your model is prolly a bit thirsty, but my Pan Euro does 18km/L no probs, and a 29 litre tank has seen me throw 55 bucks in at the Coro Loop stations with the (previously stupid) gas prices....

[Tone165]

to use that much fuel has got to be more than running a little rich. Does it blow black smoke???