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Fuel economy changed drastically! Why?

1K views 13 replies 12 participants last post by  MikeB 
#1 ·
Guys,
When I started riding for the first time in my life about 6 months ago, my '06 shadow spirit 750 would do MAYBE 90 miles on a full tank before I had to switch to reserve. That's if I was lucky. That was 6 months ago.

Since then I got better, and I'm not afraid of the bike like I was at first. What I was afraid of was over revving and damaging the engine, so I would very often ride way below optimum RPM, bike would almost choke half the time. Don't ask...

So what changed? I ride more, well, dynamically I guess you could say, I shift later than I used to, few times I even bounced off of rev limiter :D

Come this month. I filled up a week ago, 2.5 gallons exactly in the tank, and I had to flick it on reserve this morning, at exactly 120 miles on the clock (pump started to click, it's a sign it's sucking air). I really topped it off today, put 2.6 gallons in. I expect to get another 120 or so miles.

So what is it? My riding? Can too low RPMs cause worse fuel economy? Or is it ONLY the colder weather we've been enjoying in FL lately? I did notice that on those cold morning, once bike warms up, it's more zippy than I remember it being before.

Basically, for no reason I can explain, my bike went from 90 miles on a 2.5 gallons to 120! On the same exact commute to and from work each day. Same route. Same traffic. Same bike. Same driver. Same speeds. Different RPMs, more aggressive riding in fact, and colder weather.

What say you?
 
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#2 ·
90 miles on a tank is for crap. I get better mileage than you're getting now @ 120 on my 07, and most of my riding is 2 up. If you're hitting the rev limiter before shifting, your pushing it hard and your mileage will reflect that. Conservative riding will not make your mileage worse, and yes, an engine likes cooler air a lot better and will run better. Was the bike sitting before you bought it and maybe had a gummed up carb that you've cleaned up by running?
 
#6 ·
120 miles and 2.6 gallons of fuel is 46 MPG. Sounds about right running the way you are. Sustained high speed seems to kill MPG; i.e., 80 MPH runs would drop my 1100 Sabre down to 37 MPG.

I suspect that lugging the engine wide open is not good for MPG either, and as suggested other causes might have been at play.
 
#8 ·
Only thing im going to add is try not to hit limiter yes it5 there for safety but its bad. And you was most likely lugging the motor to low in the rpm range before. So on that note 120 to 150 before you switch is good all depends on down hills winds and so on.
 
#10 ·
I get 45mpg on ethanol 50 on nonethanol...
Coming across Kansas into a head wind, mileage dropped drastically!!!
Did it again Sunday too ;)
Have we started getting "winter blend" fuel at the pumps yet?

Merry Christmas
Ann & Dennis
 
#11 ·
Have we started getting "winter blend" fuel at the pumps yet?
Merry Christmas
Ann & Dennis
Not to create a debate on the OP's thread, but often wondered what's the difference between "summer" and "winter" specific gasoline. Personally I think it's just an excuse to raise gas prices while the refineries make their so called conversion.
 
#14 ·
You used to putt-putt around lugging the engine, but now you bounce off the rev limiter. Have you not heard the expression "moderation in all things?"

There are those who will tell you that the rev limiter is there to prevent damage to the engine, and thus there is no problem running up to it. That may be technically true, but the engineers who built the thing did not anticipate that you would be a regular customer at the max RPM cafe. Kinetic energy stresses on moving engine parts increase as a square of velocity, so you are not doing your connecting rod bearings any favor by putting pistons into warp speed.

Just sayin'.

And I'm too lazy to look it up, but if your engine's dyno curve is like that of most v-twins at high rpms you are not producing any meaningful increase in horsepower and are already in decline with respect to torque. So why go there?
 
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