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Old 03-25-2010, 07:36 AM   #11
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Originally Posted by i-DSi View Post
AFAIK fuel injection has not helped on motorcycles for fuel economy. I personally don't know of a motorcycle that has better economy with a FI compared to carbs. (CBR1100XX, VFR750<->VFR800,...). And if there are, than a lot more was changed (like on mine: CBF600 MY07 <-> MY08 : a whole different engine).

I also keep pressure a little bit above recommendation, but only a little bit as I don't want to take risks for the grip. Safety first.

This is interesting! My commute is 29kms one way. So now we can play in the same league! The percentage of miles driven with a cold engine is extremely important for FE. How's the benchmark so far? I will have a look in your gaslog.
I don't know what else changed in the f650 models beside the FI, but it's a common experience - the fuel injected models drink much less than the older, carbed ones.

As for the commute: I have no meaningful data yet, my last tank was the one I started at the end of December It's still better than my last winter's ones (3.33 vs 3.6+ l/100km).
But spring is here, temperature is rising and I can ride on a daily basis, so I'll have a lot of data soon. And gas may change too. I don't know anything specific, but abrupt changes in FE before and after winter are quite suspicious.
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Old 03-30-2010, 12:41 PM   #12
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...a few days later: just finished that tank: it's getting better with the weather. Now my average became 3.08l/100km (76.35mpgUS) on this distance. Sometimes it's longer though, when they close the freight gate of the industrial zone. Then I have to go 2km more. And I also visited my mother, who lives at the other end of the town, that gives ~32km for one way, but we went 2-up and with package there, so that could hardly improve my FE
(And there are a number of counter-timed lights in there. Should the fingers break of who designed their operation )
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Old 03-31-2010, 09:06 AM   #13
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Impressive!
I have the impression it's impossible to go below 4 l/100 km on mine. Today I took my CBF out (a shame: first time this year...) and my driving style can be described as 'aggressive'. Something is holding me down for driving really economical with my MC !! And my best FC ever on this bike I had by emptying a tank on one single day, driving pretty fast in the south of Belgium (wonderfull roads) with some friends on a hot day.
I do really everything I can to drive economical with my Honda Civic, but the CBF: pfff...! She always invites me to rev and overtake everything I see on the road. And you know what? I tried once or twice last year not doing this and driving her like my Civic for daily commute. Difference: only 0,2 l/100 km approx. It doesn't really seem to bother her how she's driven.
By the way: I don't know of any MC that improved FC by putting injection on an existing engine. I do know the other way around: CBR1100XX Blackbird (90's). Fuel consumption went up dramatically by switching to fuel injection. Another well known (European) example: the first VFR800i (90's). A lot thirstier with the injection than the carb VFR750, BHP almost the same.
Your BMW: I don't know all details, but engine, frame, transmission... a lot has changed compared to the original carburettor F650Funduro (you remember: that's how she was called). That's why I think it's dangerous to point at the injection for your low FC. I also remember the Funduro's consumption was lower than the Aprilia's. Guess that was because BMW used a 'classic' 4 valve cylinderhead but Aprilia a complicated 2 spark 5 valve head.
Do you know anybody else who drives a BMW like yours to compare consumption?
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Old 03-31-2010, 10:50 PM   #14
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Do you know anybody else who drives a BMW like yours to compare consumption?
There are quite a few of us

It seems that 4-4.5l/100km is kind of an upper limit for these CS/GS F650-s, you need to do something very unreasonable to make them drink more. And it's not hard to go under 4l with them, 3.5 can be pretty normal if you "drive like your Civic" (though I don't know how you do this ).

When I got the bike I started in a very conservative style (I was a complete beginner, first licence, first vehicle) in the highest possible gear (I was already aiming for efficiency so I'm not the best example) and got 3.1-3.5l/100km. It took a few months to beat 3l, but it was on a longer commute, mostly freeway where I was actually daring to go in the semis' pace.

Later when I got the taste of coasting and went to the lowest rpms of the highest gear I could beat it on a regular basis and agressive Pulse&Glide could further improve my FE. My best result is 2.38l/100km. I filled with omv carrera 100 that time and I don't know how that could affect my FE (in theory it shouldn't); my 2nd best result is 2.53l, filled with carrera 95.

Once I had an experiment when I used the freeway as it's 'intended', and was even speeding - then I actually could exceed 4l.

Now I have a shorter commute and mostly abandoned P&G (though I glide down steeper downhills, that's fun ) because that somewhat ruins the joy of the ride plus I'm not sure I'm doing a good thing overall, probably making more junk by killing something in the transmission, parts are made with energy and materials and stuff, you know. And even Teresa may get angry with me, I don't want it But I still use the highest possible gear which means shifting at 3500rpms at most. At a steady 80km/h the engine rotates at 3200 rpm in 5th. At 50km/h it's 2500 in 4th but that feels a bit of a stretch, I usually go between 50 and 60 in town, which means 3000rpm at most. This Rotax redlines at 7k (and it really does, the electronic limiter kicks in, I've tried it in my freeway experiment, 175 km/h per the speedo is the end ).

On the Pegaso, someone at f650.hu does have one and confirmed that it drinks much more than the FI f650s.
I think the difference between carbureted and FI'd models depend on many things, but if one or the other is much more thirsty there must be a serious problem. A messed up program/map, or a badly set up carb. Or something else, I'm no expert I only know 2 kinds of bikes that have both versions, they're smaller ones (Hyosung GV250, we have the carbed model; Honda CBR125R, a cute small bike I have to try some day) and there's no significant difference in the models' FE.

(OK, it's not fully true: the FI'd Teresa's FE deteriorates more at winter than the carbed Ciliegia's. Cold weather is the time when the 250 can beat the 650...)
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Old 04-02-2010, 12:43 PM   #15
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Hi Alvaro,
What is pulse and glide? I see this everywhere on this forum, but have no idea what it is.

Fuel injection: in the 90's they were definitely not more fuel economical than carburettors.
Reasons (i guess):
- cost (on a MC the % of this cost is high), so ECU capacity (mappings, speed,...) was not the best on the market.
- dimensions of the ECU. On a car it doesn't matter that much, but on a MC the smallest ECU possible was the best choice. This meant again not the most performant unit.
- amount of sensors was by far less compared to cars (no lambdasensor, mapsensor,... e.g.).
Nowadays all FI models have got all they need, just as cars and FE is good, allthough the catalyser and the 14,7/1 mixture takes some extra fuel.

The F650's reasons for being more fuel economical than my CBF (again my own thoughts):
- a one cylinder has less total friction losses than a 4-cylinder
- bit lighter bike
- less powerfull (approx 50 BHP ?)
- doesn't invite to rev the engine...
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Old 04-02-2010, 03:35 PM   #16
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Pulse and Glide (aka P&G): Accelerate, coast in neutral, accelerate again, coast in neutral again, repeat...

It uses the engine in a more efficient way and allows you to waste less, resulting in improved FE (usually). I'm not sure how appropriate it is on motorcycles.
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Old 04-02-2010, 10:49 PM   #17
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i-DSi - what you write about ECUs makes sense. Not that I don't see modern bikes drinking like crazy...

a one cylinder has less total friction losses than a 4-cylinder - it does probably count. Heard it quite a few times.

lighter - sure it is. In the beginning I was qite afraid of heavy bikes so it definitely contributed my choice. I definitely wanted something under 200kg, even if it can't be as small as the little CBR (I let myself be persuaded that a 125 won't be safe on the freeway. No regrets though, now I have something very capable )

less powerful - I'm curious how much it counts. I mean, if another firmware let this cylinder rev at, say, 8000 instead of 7000, it could be more powerful, but if I wouldn't

rev it more, could that change FE? On a side note, most of the f650.com crowd warn anyone against using this engine under 4000rpm while I seldom rev it over 4k For some reason Teresa usually makes me a cold-blooded rider. It may be because of the given name. I named her after a Claymore warrior, a very strong, highly professional woman with a touch of sick humour - and while she looks cold, she's a good person inside, you know, kind of a mother figure for the little Clare

I couldn't have done that much P&G without this attitude And it definitely helps with Teresa but doesn't seem effective with the 250cc Ciliegia. My very best is 2.86l/100km on my previous, 2*61km commute 1-up, 2nd best is 3.02; but can do like 3.2-3.3 without it 2-up... if I subtract the extra weight probably nothing remains. Even city driving doesn't hurt her FE (can cruise at 40km/h in 5th at ~3k rpm), while Teresa gets worse there (she needs 70 for 5th and 50+ for 4th).

I think the difference may be because the 250 V-twin already operates at a nice load out of town (so the higher pulse loads won't really improve its FE) while the 650 doesn't reach its efficient range when cruising at ~80-90km/h. I may be wrong, though.

Ciliegia may improve by changing the gearing, may try next time. Revs 7000 at 100km/h, could use a 'longer' transmission (someone went from 14:46 to 15:42 and reported his bike working better than before )
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Old 04-03-2010, 12:31 PM   #18
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Pulse and Glide (aka P&G): Accelerate, coast in neutral, accelerate again, coast in neutral again, repeat...

It uses the engine in a more efficient way and allows you to waste less, resulting in improved FE (usually). I'm not sure how appropriate it is on motorcycles.
Oh man, this is weird.
- you don't control your vehicle (car or MC) like you would when being IN gear all the time
- you just waste fuel while coasting in neutral

I have some kind of other tactics (for my car): I accellerate and than I put the Civic in 6th gear with an extremely light throttle and I lift my foot the moment I expect I will have to brake. When lifting my foot in 6th gear at approx 60 km/h the engine brake is almost 0, while the fuel consumption is also 0. Guess I can win nothing extra with P&G and it's another thing to concentrate on in the already hectic Belgian traffic (less safe).

Thanks for explaining Holy Cow !
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Old 04-03-2010, 12:49 PM   #19
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i-DSi
less powerful - I'm curious how much it counts. I mean, if another firmware let this cylinder rev at, say, 8000 instead of 7000, it could be more powerful, but if I wouldn'trev it more, could that change FE? On a side note, most of the f650.com crowd warn anyone against using this engine under 4000rpm while I seldom rev it over 4k
Hi Alvaro,
The advantage of having a bit less powerfull MC than my 78 BHP CBF is that yours will be much quicker in its ideal 'operating window' where efficiency will be very good. If you tune her to rev to 8000 rpm, without changine anything to the midrange, than effect on FE is nothing. Problem: it's impossible to tune an engine to go higher in to revs and produce more BHP without 'hurting' the midrange (intake will need changes, moving the rev limiter 1000 rpm higher makes no sense at all and doesn't produce extra BHP).
Imagine we both cruise at 90 km/h: yours will be more economical.
But if we both cruise at 160 km/h....mine will consume less fuel.
About the 4000 rpm limit: don't worry. They probably talk about WOT under 4k rpm. But the way we drive (extremely low load at low revs) there's no danger damaging your engine. It's especially on big one cylinders dangerous to go full throttle at a low rpm because the pressure on the bearings and cylinderwalls is high while the oilpressure might be unsufficient to fight this pressure.
In my car 1500 rpm is my underlimit. I never even touch the throttle under this rpm. And I only push the pedal very light between 1500 and 2000. WOT = 3500 rpm in my car.
On my MC 3000 rpm is my underlimit. But it's a small 600 16V... idle speed is around 1750 rpm.
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Old 04-03-2010, 04:09 PM   #20
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Quote:
Originally Posted by i-DSi View Post
Oh man, this is weird.
- you don't control your vehicle (car or MC) like you would when being IN gear all the time
- you just waste fuel while coasting in neutral
It's not quite like that.
- The only control you lose is the ability to accelerate instantly, which you already don't have with your 6th gear strategy.
- Coasting in neutral is more efficient than anything in gear. While you do spend some fuel idling the engine, you coast further than you'd roll in any gear that keeps your engine in DFCO. All those extra revolutions of the engine don't come for free.

It's certainly not right for everyone, but it is a valid technique.
- Some people don't feel that they can drive safely without having instant acceleration available (I recommend those people drive automatics or use the lowest gear possible at all times).
- Some people drive in places where it is illegal.
- Some vehicles do not accept neutral coasting (my wife's Isuzu's transmission overheats with extended neutral coasting).
- As I said, having no experience on motorcycles I can't say if it's valid for motorcycles.
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