Kawasaki ER-6

[Ixion]

Sheet - those are unbelievably piss poor figures. No wonder modern bikes have such short ranges. Speed Twin used to get over 100mpg. Velo had a 5 gallon (imp) tank, and a range of over 400 miles (not km) till resrve. That's cruising at a steady 85mph. 650cc Bonnies would get 70 to 80mpg in their day.

Why do modern bikes drink so much gas. The Alfatoy is a 3litre V6 and even it can get 30mpg on a trip. And performance would be pretty comparable (in sofar as bikes and cars can be compared) to an FZ6.

A sports 650 twin should get AT LEAST 70 mpg. Even when caned.

[zadok]

Sheet - those are unbelievably piss poor figures. No wonder modern bikes have such short ranges. Speed Twin used to get over 100mpg. Velo had a 5 gallon (imp) tank, and a range of over 400 miles (not km) till resrve. That's cruising at a steady 85mph. 650cc Bonnies would get 70 to 80mpg in their day.

Why do modern bikes drink so much gas. The Alfatoy is a 3litre V6 and even it can get 30mpg on a trip. And performance would be pretty comparable (in sofar as bikes and cars can be compared) to an FZ6.

A sports 650 twin should get AT LEAST 70 mpg. Even when caned.

I concur. That makes my heavy, old technology GTR, seem like fuel miser.

[James Deuce]

Why do modern bikes drink so much gas.

HP/L ratio. The specific HP output of most modern motorcycles is in the 150 to 200HP/L range. They flow a great deal more fuel mixture to get those outputs. Thermal efficiency is much better too, but again the amount of fuel and air consumed is much greater than "old" tech motorcycles.

All because people want to get to work first.

Bob, I'm intrigued by those test figures for the Hornet 600, because they are MUCH better than the ones I've seen in Peformance bikes or Motorcyclist. Both those publications had a similar experience to me, only getting 70-90 miles out of a tank of gas in "normal" to "sporting" use.

[erik]

Sheet - those are unbelievably piss poor figures. No wonder modern bikes have such short ranges. Speed Twin used to get over 100mpg. Velo had a 5 gallon (imp) tank, and a range of over 400 miles (not km) till resrve. That's cruising at a steady 85mph. 650cc Bonnies would get 70 to 80mpg in their day.

Why do modern bikes drink so much gas. The Alfatoy is a 3litre V6 and even it can get 30mpg on a trip. And performance would be pretty comparable (in sofar as bikes and cars can be compared) to an FZ6.

A sports 650 twin should get AT LEAST 70 mpg. Even when caned.

Very interesting post... I didn't realise modern bikes were sacrificing fuel efficiency for power like that.

[ducatilover]

Sheet - those are unbelievably piss poor figures. No wonder modern bikes have such short ranges. Speed Twin used to get over 100mpg. Velo had a 5 gallon (imp) tank, and a range of over 400 miles (not km) till resrve. That's cruising at a steady 85mph. 650cc Bonnies would get 70 to 80mpg in their day.

Why do modern bikes drink so much gas. The Alfatoy is a 3litre V6 and even it can get 30mpg on a trip. And performance would be pretty comparable (in sofar as bikes and cars can be compared) to an FZ6.

A sports 650 twin should get AT LEAST 70 mpg. Even when caned.

hmmmmm but arent the newer bikes all high strung? and producing alot more power? then again my bros is fairly old tech and it uses 11l per 150 km or so. actually 184km cos it ran dry on the way home when i got it. my dads fj1200 uses more petrol then our mazda 323 1300

[Ixion]

The amount of peak horse power produced by the motor should be irrelevant.

Typical cruising speeds for bikes haven't increased in NZ in the last 20 years. They've gone down if anything. Yeah I know your sprotbike can do 250kph. But show me where in NZ you can maintain that for even 10km let alone 100. And mpg figures are taken over long distances -tankfulls. 20/30 years ago we cruised at 80 - 90 mph , about 130 - 140 kph. I think that CRUISING speeds now are if anything less, because of road congestion and poxy plods.

To propell a bike and rider over a given road against a given wind takes a certain amount of power. Less nowdays becos of fairings. So to propel me and the old Velo at 140kph would take x hp. To propel a sprotbike and rider over the same road at 140kph should take LESS hp becos of the fairing. Yet the bike is using MORE petrol to produce LESS horsepower. Go figure. Unless our roads have changed so that the same speeds require more power. Or the airs gotten thicker.

[fishb8nz]

Totally agree. Where's the progress in design when a 650 twin's making 43 mpg. My wife's Suzy Swift can do the same around town with 4 passengers.I'd realistically expect a modern designed 650 twin, ridden carefully, to be capable of 25 km/litre=70 mpg.
What's gone wrong? Are there any bikes with decent gas mileage and reasonable power?

[James Deuce]

Kevin Cameron wrote an article in Cycle World about 2 years ago about this phenomenon. He'd had the same thought as you guys about why modern bikes use so much petrol and it came down to what I said above. 4x 34mm throttle bodies as opposed to a 26mm Amal moves a heck of a lot more fuel mixture, plus bikes are cruising at RPM figures that would have been redline (or a nasty metallic bang) 40 years ago. They also make more HP at those cruising speeds than bikes of a similar cc made at peak. Obviously it was a lot more technical than my explanation, but Mr Cameron's genius is explaning complex motorcyle mechanics in a way that even I can understand. I can burr a titanium bolt by looking at it.

[Ixion]

.. plus bikes are cruising at RPM figures that would have been redline (or a nasty metallic bang) 40 years ago. They also make more HP at those cruising speeds than bikes of a similar cc made at peak. ...

But , if cruising speeds are no higher now than they were then, why do modern bikes need more hp to cruise at the same speeds ?

[James Deuce]

But , if cruising speeds are no higher now than they were then, why do modern bikes need more hp to cruise at the same speeds ?

I let you know when I find out how long this piece of string is

[Pixie]

To propell a bike and rider over a given road against a given wind takes a certain amount of power. Less nowdays becos of fairings. So to propel me and the old Velo at 140kph would take x hp. To propel a sprotbike and rider over the same road at 140kph should take LESS hp becos of the fairing. Yet the bike is using MORE petrol to produce LESS horsepower. Go figure. Unless our roads have changed so that the same speeds require more power. Or the airs gotten thicker.

It's a fact of life.Bigger intake tracts allow for greater efficiency at high revs and revs = hp,but are much less eficient at low revs.
If you want economy,put 20mm carbs on your R1
-we'll all be doing it in 10 years

[Milky]

But , if cruising speeds are no higher now than they were then, why do modern bikes need more hp to cruise at the same speeds ?

It does seem strange doesn't it. Possibly, the HP figures you are thinking of are under full throttle at X revs - the HP that you would find on a dyno chart readout. It simply cannot be true, given that bikes are more aerodynamic/transmission efficient today, that more power is required to push them forward. A smaller throttle opening would surely suffice on a modern bike to travel at the same speed and hence similar HP.

[fishb8nz]

Hey, I'm no religeous guy but i might be seeing the road ahead.
If I'm rearward looking and want a bike with the power and fuel consumption of the 60/70s, then I should look at either a 650 single or 250 twin.
So what's it going to be?

[pritch]

20/30 years ago we cruised at 80 - 90 mph , about 130 - 140 kph.

The more things change the more they stay the same.
In the 70s on my Honda four I used to do that.
In 2005 on the current model same deal.
That's about the cruise limit for a naked bike.

Protection from the wind allows elevated velocities though,
even unknowingly...

[Oscars dad]

Anyone here heard of a new dual purpose Kawasaki based on the Er 6 motor. Seems like a very logical step and if they make it compact, sparse and gravel friendly (unlike the V strom 650 or transalp) it should be a hoot. I would buy one tomorrow.