My Honda CBF125 on 150mpg :)

[alvaro84]

It's not enough, it doesn't say anything about efficiency at different loads at the same rpm. Some say that the engine is most efficient at the torque peak, but I'm not convinced at all. And they seem to forget about the effect of different loads.

I can see only two things here: it's perfectly futile to ever rev it over ~8k; and that I'd hate that 'arrow full system' that just would make the bike weaker at the reasonable rpm range.

Anyway, how do you measure FE for these short distances? Don't tell me that you go to the fuel station and get half a liter of gas

[DanielMaia]

I thought that too. I read somewhere that the best economy is at half of the peak torque, in this case would be at 4000RPM.

No, i explain When the tank is cimpletely dry, put 0.5l of gas (a little bottle of water), and when she runs out of fuel, its simple to do the math

Yesteray i went to the gas station: 1.489? for each liter, and ask the little if i could put 1L. She said 'no problem'

[alvaro84]

That's why BSFC diagrams are used: those are nice 2D pictures with rpm and load axes so one can tell in a moment what's the best. It's hasty to say things like 'it's best at (half of) peak torque', because you can't often keep it under load at such an rpm. 'Sub-optimal' rpms often win over 'optimal' rpm depending on the load to keep the same speed. And it's just the engine, not counting aero drag, rolling resistance, and so on.

...so you carry a set of little bottles filled with gasoline? lol

Be careful though, I don't think that the fuel pump likes to run dry.

[DanielMaia]

Yup, a little bottle of 0.5L of gas in my bag

Yes, im now trying to shift in the 2600, 2700RPM range, for a motorcycle is like shift at 1500RPM on a car..but i think its the best range for economy.

Up hills im trying to put 5th gear, and press a little more the thottle, to keep the speed constant

Every down hill above 300 meters, i usually shut off the engine

Im trying a little of pulse and glide also!

There are any more technics i should test?

[cat0020]

Originally Posted by Daniel Maia

Every down hill above 300 meters, i usually shut off the engine

Im trying a little of pulse and glide also!

There are any more technics i should test?

If you pop it into gear before you come to a stop, can you re-start the engine without using the starter? or just use the kick start all the time?

[DanielMaia]

No, it has electric start, it starts very easily. Just push the button in a half of a second, and there you go

[alvaro84]

Originally Posted by Daniel Maia

Yes, im now trying to shift in the 2600, 2700RPM range, for a motorcycle is like shift at 1500RPM on a car..but i think its the best range for economy.

Huh, you're hardcore or the CBF is very special
Teresa would be very angry with me if I shifted at 2700. I know it from the sounds she makes So I shift at 3200-3500, depending on the gear and the terrain, to arrive to a usable ~2500. Uphills, 2-up, I often shift to 5th at ~3700-3800rpm, to avoid falling below ~3000... otherwise I shift at 3500 to get 2800 in 5th.

Up hills i'm trying to put 5th gear, and press a little more the throttle, to keep the speed constant

Every down hill above 300 meters, i usually shut off the engine

...then I do the same: climb the hill in 5th, at a constant 3000-3200rpm (steeper hills really need that 3200) which means 75-80km/h here. On the crest I pulse then glide until I reach 70km/h, then pulse again. Yes, these speeds are not suitable in town, but I usually ride on open roads - my commute mostly involves a hilly and slightly twisty rural 'main' road (Hungarian route 811).

I shut the engine down when I predict the next glide to be longer than 5-600m (there are 2 to 4 of them along my 25km commute depending on the direction and the in-town route). And I use the starter too, it's very hard to smoothly bump start the 650cc single. Your 125cc should be easier.

[cat0020]

I bump start my Ninja 250 near the end of a downhill coast all the time, saves the wear/tear on the starter/gear, technique is to match the gearing with the speed..

Most of the time in 2nd gear when coasting near 15-20 mph, hardly even feel the bump, above 25 mph I bump start in 3rd gear.

On my Cheap Chinese Scooter, I just flip the engine cut-off button and the engine comes back to life while coasting..

[DanielMaia]

But that will cause "wear" in the chain/sprocket/front sprocket, and in the gear box also

[alvaro84]

I've heard several times about 'wearing the starter' - is that something real? It's just an electric motor, a simple and sturdy thing, I'd expect it to drag me through the continent if I had a battery that's strong enough to fuel it.
(Yup, an F650's starter can actually move the bike and the rider, even uphills I had to try it when I lost a clutch cable )