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Old 02-20-2013, 08:23 AM   #1 (permalink)
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engine size/power for 'pulse/glide'

Something I was curious about even though it may not apply to my current research topics (as constant state driving be more common for me due to tight traffic/during busier hours in extended urban settings)... is it entirely likely that a larger engine could pull the same MPG in the real world as a smaller one under pulse/glide conditions, since it would be understressed and accelerate up to speed faster? Like maybe a Ninja 650 would get the same mileage as a Ninja 250?

I imagine some of the overstressed smaller engines would struggle afterall, I guess i'm curious if there's some formula about things like what speed range to P/G (like 40mph to 75mph?), how long it should take for best total efficiency, and other things. It may be the 250 ninja engine is adequate, but other less powerful 250cc's in the 22hp or less range like some of the v-twins would be overworked trying to pulse up to any reasonable speed. Or it could be fine going from 40-55mph, but nothing more. Or etc... has anyone worked it out to a science yet? I'm aware you can p/g anything, but what would give the best fuel mileage for extended travel if you designed around it?

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Old 02-20-2013, 08:39 AM   #2 (permalink)
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Larger bikes weigh more which can take away their power advantage (in reference to fuel economy). If there was one thing I would never do is P&G a motorcycle. During a long glide you can't really shift to neutral in a sequential transmission and holding the clutch will wear components quickly. Bump starting the engine can be dangerous if you pop the clutch on a slick spot.

Smaller bikes are way more efficient at lower speeds. Larger bikes are typically more efficient than smaller bikes at higher speeds. A rider needs to size the engine of his/her bike to the kind of riding they plan to do. If it's all city, low speed and stop and go a small scooter or motorcycle would suit better than a heavy big bike since the small bike would be lighter, nimble, and use less fuel during idle. If there is a lot of high speed interstate travel a larger bike would suit better since they have the power to maintain the speed, are more comfortable cruising and have a larger capacity fuel tank for extended range.
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Old 02-25-2017, 01:24 AM   #3 (permalink)
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The difference in acceleration between the smaller engine and the bigger engine is probably trivial. They would both be blindingly fast compared to a car. Even if pulsing 0-60, the difference is a few seconds. You'd probably use more gas with the bigger engine to do so.

Disregarding pulsing and gliding, I can address this issue from personal experience from the standpoint of sportbikes - motorcycles designed to go fast around a track, NOT get good fuel economy. I've owned a Ninja 300 and a CBR 600 F4i in the last year. The Ninja 300 was ALWAYS more efficient than the 600. The 300 is more efficient than the 600 at any speed you think you could get away with on public roads. You could try to ride your 300 at 100 MPH till the tank runs out and compare that with the 600 and you would never get better mileage on the 600. The 300 would typically give me mid 50s to mid 60s MPG. Could go about 230 on a tank before thinking about refueling. The 600 typically gives me mid 30s to low 40s and my low fuel light is on by 130. The 600 is designed to be stupid fast and is a comparative pig in regard to fuel consumption and emissions. Motorcycles in general are incredibly inefficient and incredibly polluting compared to cars due to lax emissions standards on motorcycles.

If you compare apples to oranges, a touring bike, which actually takes fuel economy into consideration, would come closer, but the smaller engine should still consistently beat it. Your best bet would be to start with something small that is available in abundance such as Ninja 250, Ninja 300, CBR 300 or 500, or whatever else you can find in your area. These vehicles are incredibly efficient as is. You could make efficiency gains with extensive aero mods if legal in your area.

If you don't want my personal opinion, DON'T read the following!
If you are going to ride a motorcycle, don't mess with pulsing and gliding! From a pollution standpoint, you're doing way more damage no matter what compared to driving a car. From a fuel economy standpoint, you're already getting way better mileage than most cars--with sporting performance factored in, there is NO comparison. From a safety standpoint, you're making an unstable vehicle even more unstable and putting yourself at greater risk from other vehicles. Ride for the thrill and try to keep the rubber side down.
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Old 02-25-2017, 09:55 AM   #4 (permalink)
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Quote:
Originally Posted by LaserSnake View Post
(SNIP)
If you don't want my personal opinion, DON'T read the following!
If you are going to ride a motorcycle, don't mess with pulsing and gliding! From a pollution standpoint, you're doing way more damage no matter what compared to driving a car. From a fuel economy standpoint, you're already getting way better mileage than most cars--with sporting performance factored in, there is NO comparison. From a safety standpoint, you're making an unstable vehicle even more unstable and putting yourself at greater risk from other vehicles. Ride for the thrill and try to keep the rubber side down.
I agree. It just doesn't work well on a cycle anyway. Compared to a car that can go DFCU or go directly into neutral when coasting, a cycle doesn't coast off-throttle well at all. Aero drag, transmission drag, and compression braking all rob any chance of efficient coasting. Even with the clutch "in" the drag is significant.

Just ride normally with efficiency in mind, and you can do pretty well.

Ridden normally, my 650cc cycle (without fairings) gets 50 MPG in-town or at Interstate speeds. Depending on conditions, I've seen low 60s. It's hard to complain about that.

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