Why is my petrol consumption rising each week?

[Sharry]

I bought my Jade 250 on the 31st January since then I first filled at at 345km at a cost of $12.70 (without hitting reserve)Then at 175km at a cost of $15.00. Then at around 250km (after it hit reserve) for $18.00 and this morning at around 250ish km for over $19.00.

My travelling doesnt change much, I go from west Auckland to South Auckland 5 days a week and then around the suburbs outside of work. I have been on the Wednesday night rides for the last two weeks.
Does any one know why it goes through such a varying amount of kms before hitting reserve and why it goes through such varying amounts of petrol for each km?

Serious positive feed back appreciated.

[Jantar]

There a few points to note:

Don't try and measure fuel consumption by the price you pay. Petrol is much more expensive now than it was in early January. Measure it by how many litres of fuel you put in.

Have you always filled up with the same brand and octane of fuel. They do differ in their characteristics.

You say your travelling hasn't changed, but your riding has. When you first got on the bike you were riding very carefully. As you get more used to it and the engine frees up you accelerate a bit harder, and ride a bit faster. Even changes in the weather can affect the distance you can go on each litre of fuel.

Just enjoy your ride and don't worry too much those details until you start endurance riding.

[PirateJafa]

What're ya complaining about? $15 gets me 100km. :P

[Sharry]

There a few points to note:

Don't try and measure fuel consumption by the price you pay. Petrol is much more expensive now than it was in early January. Measure it by how many litres of fuel you put in.

Have you always filled up with the same brand and octane of fuel. They do differ in their characteristics.

You say your travelling hasn't changed, but your riding has. When you first got on the bike you were riding very carefully. As you get more used to it and the engine frees up you accelerate a bit harder, and ride a bit faster. Even changes in the weather can affect the distance you can go on each litre of fuel.

Just enjoy your ride and don't worry too much those details until you start endurance riding.

Thanks Jantar
That is a good point. I use either Shell or BP and always 91. And yes my riding has changed with my confidence I just wouldnt have thought it could make that much difference. It could be partly due to the rush houre traffic, I dont lane split I use it as an opppertunity to practise my slow manuvouring skills.

[Sharry]

What're ya complaining about? $15 gets me 100km. :P

On that note I will consider myself fortunate.
I dont mind what the amount is, I just thought it should be more consistant.

[YellowDog]

It should be pretty consistent however you need to measure it over a given distance at a constant speed.

The start/stop riding you have been doing has so many variable factors that it is not really a test. My 18 litres would last me anything from 9 - 12 days.

Being lucky (or colour blind) with the traffic lights can make a big difference; especially if a car turns you into pizza topping.

Sounds like you are doing OK.

[James Deuce]

T

Have you always filled up with the same brand and octane of fuel. They do differ in their characteristics.


Just enjoy your ride and don't worry too much those details until you start endurance riding.

They sure do. I did a comparison of 91, 95, and 98 from the major suppliers and published it on here. Shell was by far the worst fuel consumption in the 91 and 95 categories by an average of 12% more fuel consumption for a given Octane rating of fuel. Caltex 95 was the best, with BP 98 giving marginally less distance than Caltex. I was getting around 220kms per tank on Shell 91, and 280kms on Caltex 95. 18 litre tank, 750cc motorcycle.

You're probably getting more confident and giving it more gas away from a stand still.

[xwhatsit]

250 Jade -- transverse four, isn't it? Is it the same CBR250 engine? I know GiJoe1313 complains on here that when he gives his Hornet (the successor to the Jade) a lot of snot, fuel consumption increases sharply.

If this is your first bike (apologies if it's not, just making an assumption based on 250cc), as you've got used to it you're probably giving it more throttle and more revs. I know when I first got my bike I thought even a couple of degrees of throttle was more than enough power for anyone, but now (especially on the open road) I spend a lot of time with the throttle wide open. Thankfully, being an old-style thumper, fuel consumption stays very economical no matter what I do.

There are quite a few mechanical reasons for that too, but I would've thought they'd be unlikely. Dirty air filter would cause that, or a sticky choke (been there, done that!).

[Sharry]

Thanks Jim2 I will give Shell a miss and try to keep to the local Caltex.

250 Jade -- transverse four, isn't it? same CBR250 engine?
If this is your first bike (apologies if it's not, just making an assumption based on 250cc), as you've got used to it you're probably giving it more throttle and more revs. I know when I first got my bike I thought even a couple of degrees of throttle was more than enough power for anyone, but now (especially on the open road) I spend a lot of time with the throttle wide open. Thankfully, being an old-style thumper, fuel consumption stays very economical no matter what I do.

There are quite a few mechanical reasons for that too, but I would've thought they'd be unlikely. Dirty air filter would cause that, or a sticky choke (been there, done that!).

Thanks xerxesdaphat
Yes it is four cylinder and my first bike in 27 years so I am really starting from scratch, although it has come back to me surprisingly quickly.
Shouldn't be a machinacle problem as she was serviced by Red Barron before I bought her.
But your more than likely correct in that with building confidence I am not so wary of the throttle.

[MaxCannon]

No matter how hard I slam the GN throttle to the stop it still returns the same fuel economy every week.

[fireliv]

I wish I had that kind of fuel consumption. I will hit reserve anywhere between 180km (round town riding)-120km (100kmph rinding)...

[breakaway]

Maybe it's time to Re-Jet the carbs. Maybe clean them out. Maybe you're more comfortable with the bike so you're revving it harder. Could be anything.

[steveb64]

They sure do. I did a comparison of 91, 95, and 98 from the major suppliers and published it on here. Shell was by far the worst fuel consumption in the 91 and 95 categories by an average of 12% more fuel consumption for a given Octane rating of fuel. Caltex 95 was the best, with BP 98 giving marginally less distance than Caltex. I was getting around 220kms per tank on Shell 91, and 280kms on Caltex 95. 18 litre tank, 750cc motorcycle.

You're probably getting more confident and giving it more gas away from a stand still.

Hmmm - so maybe the Duc really IS running better when I gas up with Caltex? I usually run BP 95 (or 98 when I can), but odd times I've gassed up at a Caltex, I've thought the Duc felt like it was running better afterwards... Thankyou for that little gem, Jim2!

[xwhatsit]

No matter how hard I slam the GN throttle to the stop it still returns the same fuel economy every week.

Yep -- 250 singles are wonderful for that. Mine kicks out a steady 26-29km/l (~70mpg) whether riding in town, beaning it on the open road, carrying luggage, pillion, whatever. Could also be a certain mechanical sympathy on my part, after rebuilding the engine once I don't want to do it again for a while.

Four cylinder engines on the other hand... why is that? Can run quite economically, until you open the throttle a bit and everything changes. Inconsistent.

[90s]

Keep a fuel economy spreadsheet. At the time of your first post there really is not enough data for you to correctly figure out overall economy, even without considering the changes in riding style etc.
Fill up and write on the reciept the ks. Then your have the Ks, Ls & fuel type to enter into excel or something, and then examine the average over time. You might then see patterns. I've been keeping a log on my current bike since I got it, and across 3 fills riding the same route same way there can be a lot of variation - up to 10mpg. But this is 'noise' caused by a 'fill' not being quite full etc etc. The average shows a fairly constant 51mpg.

This type of log is useful because it once you have some good data in there you may really see some type of decline in economy where other factors such as your ride haven't changed. I always find this a good early warning system. A real marked decline and then yes, you would want to consider getting the carbs balanced or looking for other problems.
Sorry for the geeky reply. I love data, me.