Fuel consumption vs RPM vs throttle setting?

[dynamite9585]

ok, my fuel consumption on the open road isn't quite where i would like it yet.
a carb clean and a tune took me from 13km/l to 17km/l

on the open road in 6th it's bloody hard to keep it at open road speed. i need to be holding almost full throttle just to maintain speed.

put it in 5th or 4th even i can ease off on the throttle a fair bit but rpm is increased bt 1-2k RPM.

what one is more likely to increase my range?

[imdying]

on the open road in 6th it's bloody hard to keep it at open road speed. i need to be holding almost full throttle just to maintain speed.Something is well up with that then.


what one is more likely to increase my range?Larger throttle openings use larger amount of gas.

[Gibbo89]

ok, my fuel consumption on the open road isn't quite where i would like it yet.
a carb clean and a tune took me from 13km/l to 17km/l

on the open road in 6th it's bloody hard to keep it at open road speed. i need to be holding almost full throttle just to maintain speed.

put it in 5th or 4th even i can ease off on the throttle a fair bit but rpm is increased bt 1-2k RPM.

what one is more likely to increase my range?

17km/l is about the norm for an inline four 250 i reckon

[dynamite9585]

17km/l is about the norm for an inline four 250 i reckon

my g/fs CBR gets 23! i expected range to me closer to 20 even if hers is better than average

[MSTRS]

They are all different as far as consumption is concerned, BUT full throttle to maintain 100kph is WRONG. Something needs sorting there.

[Gibbo89]

my g/fs CBR gets 23! i expected range to me closer to 20 even if hers is better than average

be interesting to see if an 88 to 90 cbr owner could compare to 23. they got a bit more high performance after the 86/87 ones i think

[quallman1234]

Perhaps you could go for a large rear sprocket?

I know some guys who race cbr250's at manfield, run quite short gearing compared to standard and still only just get into top. Obviously you don't want it to revving its balls off.

[porky]

are the sprockets (both) standard? By what you say the motor revs out ok, but bogs down in 6th?

[dynamite9585]

are the sprockets (both) standard? By what you say the motor revs out ok, but bogs down in 6th?

as far as i know both sprockets are standard.
it doesn't bog down so much, just starts to wash of speed.

just went out for another ride, it's not full throttle to maintain it, just a little over half. will put some markings on my throttle so i can get a better look

[Gibbo89]

quite the perfectionist aren't ya dynamite? :yes:

[dynamite9585]

quite the perfectionist aren't ya dynamite? :yes:

yea i get mild ocd.
then i get really pissed off, think fixing it is too much hassle and just live with it

[Gibbo89]

yea i get mild ocd.
then i get really pissed off, think fixing it is too much hassle and just live with it

like most of us... haha

[Juzz976]

Fuel consumption = rpm² x displacement

5.88L / 100k Sounds about right, 250's are not as efficient above 70km/hr because of too much rpm.

You'll probably find it will want to sit at 110-120 in 6th and 100 in 5th, depends on bike tho most have a sweet spot 4 each gear. The TL1000R I want to get likes 120 so I might have issues with the Demerit regulator.

[onearmedbandit]

Fuel consumption = rpm² x displacement



Does that formula take into account drag and gearing in some way or other?

[SMOKEU]

be interesting to see if an 88 to 90 cbr owner could compare to 23. they got a bit more high performance after the 86/87 ones i think

My one does around 4L/100km if I'm cruising on the open road.

[Mrs Shrek]

:blink:
Might have to change your bike. I only get 30 kms/l :whistle:

[DrunkenMistake]

be interesting to see if an 88 to 90 cbr owner could compare to 23. they got a bit more high performance after the 86/87 ones i think

I got an 89 CBR250 MC19, with about 6,300 km on the clock and I usualy ride an average speed of 100-110 and I can get about 18 - 19km/l In the manual it says it can do 300km on a tank of gas including the reserve and It falls about 20 km short of meeting that mark.

[DMNTD]

For the love of all things shaven...just ride your bike and enjoy it :scooter:

[p.dath]

my g/fs CBR gets 23! i expected range to me closer to 20 even if hers is better than average

Trying to remember back to my CBR250RR. I'm pretty sure it didnt get close to 20l/100km. 17 sounds more reasonable to me ...

[Spearfish]

Unless you can put it on a dyno its hard to know where the engines sweet spot starts, and especially, finishes and how that relates to your own riding situation.

A rudimentary way is a be in to high a gear then open the throttle and feel when it starts to pull take a note of the rpm then do a run at your preferred riding speed and gear and see if your in the rev area the engine felt strongest on the test, maybe a lightly larger rear cog would get you just inside the power area. If you just drop out of top gear the next one down could be slightly too low with unnecessary revs for touring if you know what I mean.


I did the same experiment with a small xl125 carrying just my fat arse then changed the gearing slightly had the same economy and slightly more speed. I did the same thing when I loaded up the bike with camping gear and had better numbers all-round than using the standard gearing.

[SMOKEU]

Trying to remember back to my CBR250RR. I'm pretty sure it didnt get close to 20l/100km. 17 sounds more reasonable to me ...

Most V8s wouldn't even drink that much.

[george formby]

I have always been led to believe that it is not just revs that effect performance & fuel consumption. If your in 6th at 100kmph but the revs are to low for the motor to make decent power your flogging it. Better in a lower gear & higher revs with less load on the motor & a smaller throttle opening.
Possibly, maybe, dunno. I make coffee.:mellow:

[Jantar]

Fuel consumption = rpm² x displacement.....
So why does my 1000cc VTwin use more fuel at 4000 rpm than my 1200cc IL4 did at 4500 rpm? :mellow:
(Then there's my 500cc which uses twice as much fuel at 3500 rpm than either of them.)

[_Shrek_]

:blink:
Might have to change your bike. I only get 30 kms/l :whistle:

30ks per ltr thats coz you only do'n 80-90k's an hr :bleh:

:hitcher: but on a good note I'm getting 19.5 k's to the ltr not to bad for a 250kg tank + a Shrek :Punk: