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Why are motorcycles not better?

Amos Malone

Amos Malone

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Something I was thinking about. Motorcycles used to be highly efficient machines that, compared to cars, had to bonus of being able to go FAST.

Honda designed engines have recently won numerous GP championships and have just won the F1 world championship. Honda engines should be peak of efficiency and power.
The new Honda Hornet 2023 has brand new high tech engine design. Specs are very respectable compared to the competition. About 90 hp out of 755cc, under 200 kilos, 6 gears. It uses 4,1 liters per 100 km (manufacturers number, real life is higher). OR 16,5 liters per 100 km per ton. A measurement I've made up, but stay with me, it's only for comparison.
The car I recently sold (Kia Rio GT-Line) has 100 hp out of 1 liter engine (It was available with 120 hp 1 liter engine), 1350 kilos, 5 gears. In 39000 km it used 5,3 liters per 100 km with me driving. That is under 4 liters per 100 km per ton. And it had space for 4 passengers and luggage. Also; Air-Co, heated seats, heated steering wheel, reverse camera, sat-nav, etc.

Why are modern motorcycles not more efficient or faster?
 
"Consequently, the drag coefficient of a motorbike can range from 0.5-1.0 which is double that of a modern car. Total drag is calculated by multiplying the frontal area by the drag coefficient as well as the density and velocity of the fluid."
 
Amos Malone said:
The Hornet is better, but it should be so much more better, especially gas mileage. The Kia is accelerating 6 times the mass, yet the Honda is only getting 20% better mileage. It's worth noting that the Kia is not a hybrid.
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If you compare the Kia to a bike with similar hp/weight the bike comes out way ahead. For example, the Honda Monkey is 9.7 hp at 105 kg. So it has a hp to weight of 0.09 hp/kg which is more than 20% better than the Kia. The Kia gets 24 km/L compared to the Honda's 80 km/L so the Honda is more than three times more fuel efficient.
 
The drag ecoefficiency of a cube is about 1.
My conclusion. Motorcycles need more streamlining. Graig Vetter where are thou. :-)
 
Craig's bike were pretty funky looking but boy could they cheat the wind.

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I went from a SOHC CB750 to a FZ07 to a FZ 09. From that perspective, new bikes are damn amazing! 😁

But I know exactly what you mean. New bike performance is top notch, but it does seem to require more fuel than you'd expect.

Then again, I've never had a car get nearly 50mpg that couldn't accidentally wheelie when passing at interstate speeds, so I'm content with my bike :)
 
Bikes don't produce the torque that large cars do, and bikes don't have enough mass to coast well. Especially with the ever-loved oring chain, bikes need constant open throttle to maintain speed. And bike engines generally cruise at high rpms compared to cars.

If car engines also cruised at ~6k rpm their fuel efficiency would plummet. But they have enough mass and torque that they can loaf down a highway once up to speed.
 
Amos Malone said:
Exactly what I mean. The Monkey weighs less than 10th of the car and only gets about 3 times the mileage. It should be better.
My conclusion. Motorcycles used to be substantially better than cars. Cars have improved much more than bikes in the last few decades. It's time for motorcycles to take a commanding lead again. How can we do that?
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You are looking at the wrong metric(s).

Look at horsepower per liter and then line a car and a bike....
 
I could be that motorcycles were as optimized as they could reasonably get and that cars were just that much worse and are now finally catching up. What are you proposing that needs to be done? Better mileage?
 
"What needs to be done?" That's a good question. Mileage is in the list, but just as a sub item.
Most motorcycles are still better than cars. Faster, better mileage. However, their weight and size advance should make them so much better than cars than they are. I'd say efficiency needs to improve. Toyota manufactures one of the milestone engines in efficiency, the Dynamic Force Engine, with about 40% efficiency. Mazda claims to be about to overtake that with their forthcoming Skyengine 3, which is supposed to deliver 53%.,Nissan is developing an engine with over 50% efficiency. Is it a coincidence that none of these manufacturers makes bikes?
Car development over that last few decades shows that there was plenty of room for improvement, and car manufacturers have improved a lot. Motorcycle manufacturer have in general have not improved as much. There are some good motorcycle models though. Take my scooter for example. It has 16,6 hp out of 156cc and I've averaged 2,1 liters per 100 km for the last 2300 km (after I put the big screen on the front). The technical solutions in the engine is what makes it interesting. The starter and alternator are one unit that is not bolted on the engine as much as designed into the engine. They are as much part of the engine as the ignition system. The radiator for watercooling is also part of the engine. Remove the engine from the bike and the radiator comes with it, no long hoses to disconnect. This saves lot of weight from the scooter and that increases efficiency by itself. Imagine what it could do if it was properly streamlined.

We know that aerodynamic on motorcycles are bad. This guy took a small motorcycle and streamlined it, which gave him gains in efficiency (the results are on the page, with credit to some Greg Vetter ideas). He then started improving rolling resistance. This is not a one-for-all-solution, but it's is a marked improvement. I must ask why no big motorcycle manufacturer seems interested in offering aerodynamic solutions.
 
Maybe there isn’t enough of a market for “econobox” motorcycles to justify the expense and effort to maximize the mileage?

Automotive advertisements often tout their mileage achievements. How often do you see motorcycle ads boasting about MPGs?

Low revs, low power, hard tires, long gears, etc sounds like nothing I’m interested in.
 
Amos Malone said:
Something I was thinking about. Motorcycles used to be highly efficient machines that, compared to cars, had to bonus of being able to go FAST.

Honda designed engines have recently won numerous GP championships and have just won the F1 world championship. Honda engines should be peak of efficiency and power.
The new Honda Hornet 2023 has brand new high tech engine design. Specs are very respectable compared to the competition. About 90 hp out of 755cc, under 200 kilos, 6 gears. It uses 4,1 liters per 100 km (manufacturers number, real life is higher). OR 16,5 liters per 100 km per ton. A measurement I've made up, but stay with me, it's only for comparison.
The car I recently sold (Kia Rio GT-Line) has 100 hp out of 1 liter engine (It was available with 120 hp 1 liter engine), 1350 kilos, 5 gears. In 39000 km it used 5,3 liters per 100 km with me driving. That is under 4 liters per 100 km per ton. And it had space for 4 passengers and luggage. Also; Air-Co, heated seats, heated steering wheel, reverse camera, sat-nav, etc.

Why are modern motorcycles not more efficient or faster?
Click to expand...
Turbos are wonderful things,and the Kia makes good use of the turbo and if the bike had the build and incorporated turbo tech the Kia would be just another also ran.
 
DJ_MI said:
Maybe there isn’t enough of a market for “econobox” motorcycles to justify the expense and effort to maximize the mileage?

Automotive advertisements often tout their mileage achievements. How often do you see motorcycle ads boasting about MPGs?

Low revs, low power, hard tires, long gears, etc sounds like nothing I’m interested in.
Click to expand...


Fact : South America and places like Thailand are full of cheap econobox motorcycles.
 
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Sort of a parameter tossed salad here.

One silent elephant might be thinking something like write a law today that requires any moto sold four years from now and thereafter to double its present fuel efficiency. For starters. Don’t hit the target? Don’t sell the bike.

Pretty sure car companies have 40 plus years of serious incentive and moto makers not.

Don’t shoot messengers.
 
Amos Malone said:
I just want to see the same development as in cars. In the last few decades cars have gone from 2 liter engines with 100 hp to 1 liter engines with 100 hp, and have twice the mileage.
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That development was forced by law. There was an epic political firestorm. The cost/benefit for doing motos the same isn’t even on any realistic imagination list.
 
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