Author Topic: fuel consumption and performance  (Read 2735 times)

Offline MikeN

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fuel consumption and performance
« on: 14.05. 2010 22:26 »
I was thinking. In the 50's and 60's a typical medium size family car,like an Austin Cambridge or Cortina or something would trundle along and return about 25-30mpg (imperial gallons).A smaller car like a Morris minor or A35 maybe 35-40ish mpg. A typical high performance motorcycle of the period like an BSATri/Norton etc twin would easily out perform these cars and still average 60-70mpg.
 Nowadays with improvemnts in design a typical medium size car can do 40-50mpg and a small one can do 50-60mpg or even more.
With this in mind, i would expect a modern sports bike ,(whatwhat ever the present day Japanese equivelent of the Road Rocket or Bonnie is), to be returning around 100mpg.
I dont know anything about modern bikes,but I suspect this is not the case.if not .Why?
Mike

Offline Triton Thrasher

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Re: fuel consumption and performance
« Reply #1 on: 15.05. 2010 06:18 »
.if not .Why?
Mike

Because fuel economy is not a big selling point for sports bikes.

Offline MikeN

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Re: fuel consumption and performance
« Reply #2 on: 15.05. 2010 17:01 »
Im sure, but then I doubt anyone bought a Bonneville with economy in mind either.
And yet it would still have been way faster and considerably more economical than a car of the time.

Offline Triton Thrasher

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Re: fuel consumption and performance
« Reply #3 on: 15.05. 2010 17:51 »
Ride a Bonneville fast and it will do about 40mpg. That's not fantastic economy.

A modern bike doing "fast Bonneville" speeds might manage 40mpg too.

Offline MikeN

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Re: fuel consumption and performance
« Reply #4 on: 15.05. 2010 21:00 »
Ride a Bonneville fast and it will do about 40mpg. That's not fantastic economy.

A modern bike doing "fast Bonneville" speeds might manage 40mpg too.

OK ,Thats the point im trying to make. You say an old Bonneville has similar fuel consumption to a modern bike ridden at Bonnie speeds.
Whereas im pretty sure a modern car will use a lot less fuel than an equivelent car from the 50's at similar speeds .
Or, it can also go considerably faster and still be using less fuel than the old car.

Offline duTch

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Re: fuel consumption and performance
« Reply #5 on: 14.01. 2014 23:19 »

 Did a search for 'fuel consumption', and this came up.

  At the end of '76, I did a impromptu trip Brisbane to Sydney on my '58 R.Rocket. It was when there were fuel strikes/shortages, so I strapped a gallon oil can full on the back.
 Did about 65-70 mph all the way,where possible (was just before radar guns !), and on the return trip I filled up just out of Ballina, and made it back to Holland Park, (almost central Bris.) I think was just on 200 miles so works out about 65 mpg (?), with I think a 3-1/2 gallon tank.

  Now to current bike,(A10 Plunger, 7.25 cr, S/R head) the tank holds 13.75 litres, a bit smaller than it should be, and I have to fill up about every 100 miles (+10% for inaccuracy in speedo-1620 with 2.0metre wheel circumference).

 Unless all my conversions are out of whack that = ~ 40-45mpg

 This doesn't seem good enough- slightly better on 98 than 91, but roughly the same, and performance too.

  Any clues? is fuel gone to crap that much??
Started building in about 1977/8 a on average '52 A10 -built from bits 'n pieces never resto intended -maybe 'personalised'
Have a '74 850T Moto Guzzi since '92-best thing I ever bought doesn't need a kickstart 'cos it bump starts sooooooooo(mostly) easy
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Offline muskrat

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Re: fuel consumption and performance
« Reply #6 on: 15.01. 2014 03:46 »
It sure has Dutch.
I'm getting 50 MPG out of the A7 sitting on 60 MPH. In about '81 the same bike got me at least 60 MPG.
On a good day I get 40 MPG out of the cafe and 28 *eek*MPG out of the rHonda phore. 20 MPG out of the 4.2Lt 6 cyl Ford ute.
12 MPG out of the A7SS on methanol  *eek*.
Price for 98 here is $1.75/Lt = $7.95/gal
Cheers.
'51 A7 plunger, '57 A7SS now A10CR,  '83 CB1100F, 88 FXST .
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Muskys Plunger A7

Offline terryg

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Re: fuel consumption and performance
« Reply #7 on: 15.01. 2014 07:55 »
Hello Musky - so you're paying about half the UK petrol price AND getting a better ration of sunshine.  I'll try not to think about that for too long.
Terry
'57 'SR', '59 SR, '63 RGS

Online KiwiGF

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Re: fuel consumption and performance
« Reply #8 on: 15.01. 2014 10:15 »
My A10 (30hp?) before new 376 carb 50mpg keeping below 70mph, after new carb 60mpg, my 2010 Triumph 675 Street triple (108hp) ridden sensibly ( which is hard to do) 50mpg, but it does a lot less ridden fast   *lol* *wink2*

My 1988 honda GB500TT (40hp) which I sold a few years ago to buy the A10 did around 80mpg even when thrashed. Is that more than the 500 goldie it was imitating?

My 1999 1400 v twin suzuki (60 hp?) does 60mpg when ridden sensibly but weighs a LOT.

Conclusion? Modern bikes are around that use much less fuel than 60 year old bikes with similar hp, but hardly anyone buys them?
New Zealand

1956 A10 Golden Flash (1st finished project)

1949 B31 rigid “400cc hot rod” (2nd finished project, + favourite bike)

1949 C11 rigid, but why!!! (cos it was cheap)

1937 B21, project missing parts, mission impossible?

GL1800 Goldwing, well, the wife likes it

KTM 950 ADV, cos it’s 100% nuts

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Offline unclerob

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Re: fuel consumption and performance
« Reply #9 on: 15.01. 2014 10:24 »
Back in the 80's I used an A10 for commuting to work ...a 40 mile trip...and used to easily get 60mpg but I think the difference then was how much easier it was to get about. I used to try and do the whole trip without coming to a stop and putting my foot down....and often managed it!
Doubt you could do that nowadays...

Offline Ethelred

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Re: fuel consumption and performance
« Reply #10 on: 15.01. 2014 10:25 »
Interesting what Musky and Dutch are saying about the drop off in economy because of modern fuel. It makes modern car fuel economy seem even more impressive, or perhaps it's just formulated to work better with fuel injection.
If economy was an issue with bikes then someone would have built a modern diesel multi by now.
'59 A10

Online bsa-bill

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Re: fuel consumption and performance
« Reply #11 on: 15.01. 2014 14:52 »
I'm with Dutch and unclerob - can only be our modern fuel

Used to get 60 mpg two up on the Flash in the 60s now much much less probably 40 - 45
All the best - Bill
1961 Flash - stock, reliable, steady, fantastic for shopping
1959 Rocket Gold Flash - blinged and tarted up  would have seizure if taken to  Tesco

Online cyclobutch

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Re: fuel consumption and performance
« Reply #12 on: 16.01. 2014 12:12 »
My Picanto does pretty much the same mileage as my larger bikes. And if you'll excuse the mixed units that's around 10 miles (what my speedo/odo reads in) per litre (what they sell our gasoline in).

Certainly emissions kit has had an effect.

Talking mpg, my little V50 manages maybe around 55, and my A10 really ain't that good. The Sportster is not too bad. I'm sure that my '79 750 Bonnie in the day and despite being absolutely hammered everywhere, all of the time, would manage 60 - 65.

Even accepting the high performance of modern motorcycles I think that the mileage they can manage is absolutely shocking. I'm thinking that Honda have produced something quite recently focussed on economy using effectively half of one of their car engines. But it still gives, to my mind, poor returns.

As things stand I don't see that the modern motorcycle can really be viewed as serious transport.
Various, including ...
'58 Iron Head Flash Bitza


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Re: fuel consumption and performance
« Reply #13 on: 16.01. 2014 23:03 »
Another factor in the mix....Im going to Auckland jn a weeks time to see the classic bike show. Abouf 2000km round trip for my street triple. I estimate 120l of petrol needed cost at circa $250 nz, and 20% of my tyres worn out which as they are circa $600 the pair works out  at a cost of $120nz....

So the cost of tyres makes modern sports more expensive to run than cars and older bikes  as well......

But a modern tyre has FAR more grip than a skinny wm2 tyre!
New Zealand

1956 A10 Golden Flash (1st finished project)

1949 B31 rigid “400cc hot rod” (2nd finished project, + favourite bike)

1949 C11 rigid, but why!!! (cos it was cheap)

1937 B21, project missing parts, mission impossible?

GL1800 Goldwing, well, the wife likes it

KTM 950 ADV, cos it’s 100% nuts

1952 Armstrong Siddeley Whitley for rainy days (with wife

Offline duTch

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Re: fuel consumption and performance
« Reply #14 on: 17.01. 2014 09:41 »

 Ok just to confound things a little, since owning my Guzzi (850T), from '92, I've consistently ranged 200 miles (yes, miles- it came from the US) till I hit reserve, and it takes 20 litre to refill from there.

 Using around town (reluctantly), it's down a bit, but did a trip up the coast last weekend, and as per usual right on cue- 200 mi>reserve..... 10 mile per litre (16 k/l).
 
 So that kind of throws theories to the wind...??  (I usually run on BeePee 98 since Super dissappeared)
Started building in about 1977/8 a on average '52 A10 -built from bits 'n pieces never resto intended -maybe 'personalised'
Have a '74 850T Moto Guzzi since '92-best thing I ever bought doesn't need a kickstart 'cos it bump starts sooooooooo(mostly) easy
Australia