My fuel economy is utter butts. What can i do to improve it?

[helloindustries]

'hoy all.

I'm getting about 25mpg right now.
I ride 100% inner-city, so i get that there's a reduction in the economy rating of 55mpg, but surely this is too much?

I don't rev the arse off of it, and i tend to pootle along at about 3.5-4k revs. I do like to accelerate up to the limit where i can, but it's not often.

[darrsi]

Just the normal maintenance stuff can help.


Carb balance
Clean air filter/plugs/oil/coolant
Correct tyre pressures
Correct chain tension/slack
Stop unnecessarily ragging it
Smoother acceleration
Lose any excess baggage

[Ebme Geek]

What do the spark plugs look like, running rich ?
How is your idle, all four chokes closing properly
 
If motor running smooth and good, plugs nice tan colour, fuel leak ?
 
I live on an island where the max spead limit is 35 (ya, right  ) and that fuel consumption sounds horrific even to me, something is wrong

[noggythenog]

Just to confirm then......you're getting somewhere around 120 miles to a full tank are you.......mind the reserve light comes on way early?

[stevierst]

Christ, I got more than that out of my gen II when I rode it like it was nicked!!!

There's some serious problems with your machine dude.

Probably ALL those 'things' mentioned above will be wrong with it being that bad.

[helloindustries]

• Carb balance - I've been meaning to do this anyway
• Clean air filter/plugs/oil/coolant - Plugs/oil/filter are all recent (less than 5 months old) but will check. Intending to replace air filter with a K&N
• Correct tyre pressures - Yep
• Correct chain tension/slack - Yep
• Stop unnecessarily ragging it - Aww... Well; I don't take it over 8k revs, and i tend to ride between 3.5 and 4k 95% of the time.
• Smoother acceleration - Aww...
• Lose any excess baggage - Well, i *could* do with losing some weight...
• What do the spark plugs look like, running rich ? - Will check
• How is your idle, all four chokes closing properly - Will check
• If motor running smooth and good, plugs nice tan colour, fuel leak ? - Seems to be - Will check - No.

I'm getting about 85-95 miles to a tank right now.

[fazersharp]

'hoy all.

I'm getting about 25mpg right now.
I ride 100% inner-city, so i get that there's a reduction in the economy rating of 55mpg, but surely this is too much?

I don't rev the arse off of it, and i tend to pootle along at about 3.5-4k revs. I do like to accelerate up to the limit where i can, but it's not often.

Have you tried going for a ride out of the city to see what you get, and how many miles has the bike done

[darrsi]

I was just about to jump in and say I can fully understand if you're stuck in city traffic every day, like I am, then mileage and fuel economy tends to be irrelevant.
People don't believe me when I say I can get totally stuck on the way to and from work, and on a bad day 5.5 miles can take 40+mins, especially like recently when the traffic lights have stuck on red FOUR times, and even when riding on the wrong side of the road and taking every back route and short cut i know....BUT....85-95 miles per tank is just not right at all, and I'd be looking for a hole in the tank and a big trail of fuel behind me!
That is literally drinking fuel twice as much as it should be.

[noggythenog]

This fuel must be going somewhere.....either straight on the road, out the exhaust or into the oil...........what's your oil level like out of interest?......can you see daylight in the sight glass or is it over full?


You could probably redline in 1st on a good bike and get better mpg than you're getting.


I got better mpg than that whilst one of my carbs was dumping fuel all over the road.

[JoeRock]

How are you working your mpg out mate? You're not filling up when the light comes on and thinking you're putting 16L in when you're only putting about 8 in are you? Might be your light coming on early and you've not realised - don't laugh, I've read that happening before!

[helloindustries]

How are you working your mpg out mate? You're not filling up when the light comes on and thinking you're putting 16L in when you're only putting about 8 in are you? Might be your light coming on early and you've not realised - don't laugh, I've read that happening before!

Taking capacity of tank, cost to fill, noting that when the light comes on, it's at just about a fiver's worth of fuel. Also using the trip meter and offsetting that with cost to fill to max. If that makes any sense.

I ran it dry recently (to my shame) and the trip meter still read less than 100 miles.

To answer other questions:
Bike has done 42000 miles.
There are no fuel leaks.
Haven't noticed any kind of fluid coming out of the exhaust.

Everything else is getting looked at in January.

[darrsi]

Makes no sense. 

[noggythenog]

What about the oil level.....did you check that?.....you should have an air gap at the top of the window?


Have you checked your wifes car?

[helloindustries]

What about the oil level.....did you check that?.....you should have an air gap at the top of the window?


Have you checked your wifes car?

No and no because i don't have one of those.

[fazersharp]

Mystery over I think I know what is going on

[darrsi]

How does the bike run generally?

Is it throaty, jittery, stuttering, smoking, etc? 

[stevierst]

I think if it was THAT rich it wouldn't run at all, so the fuels going somewhere, and more than likely not the combustion chamber at detonation.

[JoeRock]

How are you working your mpg out mate? You're not filling up when the light comes on and thinking you're putting 16L in when you're only putting about 8 in are you? Might be your light coming on early and you've not realised - don't laugh, I've read that happening before!

Taking capacity of tank, cost to fill, noting that when the light comes on, it's at just about a fiver's worth of fuel. Also using the trip meter and offsetting that with cost to fill to max. If that makes any sense.

I ran it dry recently (to my shame) and the trip meter still read less than 100 miles.

To answer other questions:
Bike has done 42000 miles.
There are no fuel leaks.
Haven't noticed any kind of fluid coming out of the exhaust.

Everything else is getting looked at in January.

So to confirm:
Look at miles
Divide miles covered by litres of fuel put into tank.


Multiply that figure by 4.54


That's your mpg?

[Jules-C]

How are you working your mpg out mate? You're not filling up when the light comes on and thinking you're putting 16L in when you're only putting about 8 in are you? Might be your light coming on early and you've not realised - don't laugh, I've read that happening before!

Taking capacity of tank, cost to fill, noting that when the light comes on, it's at just about a fiver's worth of fuel. Also using the trip meter and offsetting that with cost to fill to max. If that makes any sense.

I ran it dry recently (to my shame) and the trip meter still read less than 100 miles.

To answer other questions:
Bike has done 42000 miles.
There are no fuel leaks.
Haven't noticed any kind of fluid coming out of the exhaust.

Everything else is getting looked at in January.

I'm confused about the "cost to fill" the cost is nothing to do with the fuel consumption it's the number of litres to fill you need.

I'm getting just over 50 mpg for 5 mile commute in town everyday and I think my poor bike's totally forgotten when it had a good run out of town.

[helloindustries]

Fazersharp: YES. Alien bastards! Coming to my country, stealing my fuel...
Darrsi: Seems to run just fine. Had it test ridden a couple of times an no issues have  been reported other than that it's a bit soft up until 5k revs. But that's normal for this bike as far as i can tell.
JoeRock: Something like that, i think. I'm not great at maths.
Jules-C: True, but i know from experience that when the fuel light comes on, i have about 30 miles left and a full tank costs £16 at my usual petrol station.

[darrsi]

I let my bike go lower than normal a few days ago and I put just over £16 in so that's about right.

Ropey running under 5000rpm would hint that the carbs would appreciate a balance, and you will notice a nice difference in slow moving traffic when that's done.

Other than that, the mileage certainly still doesn't make much sense? 

[Fazerider]

Like everyone else, I can't really believe that your bike can be so sick that it's returning a genuine 35mpg.
If the carbs were flooding or set massively rich you'd notice poor running and difficulty starting.
If the brakes were dragging to that degree you'd notice poor performance and a disc being red hot.
If the tyres were flat you'd notice abysmal handling.
So, assuming you're not towing a caravan,  either the odometer's telling you lies or you are getting the sums wrong.

[His Dudeness]

Maybe it's always been running rich since you bought it so you've just gotten used to it performing that way? All I can think of is there's a problem with the air filter or carbs. If you've got some mechanical skills check the air filter and take the carbs out and check and clean them. Also take the spark plugs out and check them. If you've been using a mechanic to service your bike there's a chance he hasn't put a new air filter in when you thought he did. It does happen sometimes. People ask for a full service but dont specify exactly what they want done. Also check for a badger in the airbox, that'll ruin your mpg

[helloindustries]

First week of January i'll be taking it in for a poke-about.

Will be:

• Checking plugs
• Checking choke/s
• Replacing air filter with a K&N
• Replacing oil and filter
• Checking state of carbs/clean
• Balancing said carbs
• Checking 02 levels.

[darrsi]

First week of January i'll be taking it in for a poke-about.

Will be:

• Checking plugs
• Checking choke/s
• Replacing air filter with a K&N
• Replacing oil and filter
• Checking state of carbs/clean
• Balancing said carbs
• Checking 02 levels.

Treat yourself for Xmas and add a fuel filter to that list for an extra few quid. 
I presume your calipers are okay and not sticking/binding as well, 'cos that certainly wouldn't help matters?