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Discussion Starter #1
Lately I've noticed that my gas mileage has decreased significantly. Normally, no matter how hard you flog her, you can get ~100 miles before the gas light pops on. Which is what everybody else states as well.

Recently, on my trips to Daytona and just normal driving, seems like the most I can squeeze out a tank of gas is 90ish miles. Today, my light came on at 85 miles. 85-90 miles before a light comes on, that's like a 10-15% loss on my gas mileage.

So what would cause this? My performance is up to par according to my recent dyno runs and 1/4 mile dyno runs, I'm just eating gas more than usual. Any ideas?
 

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I know it's an obvious suggestion Nate but have you got a leak somewhere in the system? :idea:
 

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Do you have a fuel leak? My only indication of a leak was poor fuel economy. Turned out one of the o-rings in the fuel pipe quick-connects had perished a bit and it was leaking. It was not notiecable while standing still but must have been fairly gushing at speed and evaporating.

Si
 

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oicdn said:
Lately I've noticed that my gas mileage has decreased significantly..... So what would cause this? .... Any ideas?
I'm no expert but differing gas formulation is also a possibility. Even though Florida virtually has no winter different gas companies have different "winter" formulations that can hurt fuel economy. Most increase their "oxygenation" and increase ethonol which hurt mileage - especially in warmer weather.

Tom
 

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Discussion Starter #5
I've looked and haven't found anything. Which rings should I check first?

I have however noticed, that when I top it off, and the bike sits for a minute or two, it somewhat floods my engine.

It's hard to start, and runs really lumpy and crappy for a awhile. Like 30 seconds to a minute and I have to keep the RPMs up for a little till it "burns it off".

It only happens when I top her off, not at every gas stop, so I can only get like 4.5 gallons if it's bone dry. If I top her off at 5, it overflows out the overflow if it sits for a second. I've noticed that there will be a puddle of fuel under my bike coming out the overflow hose and I'll lose like a quart of gas. But it's wierd, cause if I top her off, and just go without sitting for a second, no such issues. Well, I dunno if she still overflows, but the crappy running for 30 seconds to a minute doesn't happen...
 

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"Tpadden's" post is exactly correct.

The fuel blends for "winter" use are the culprit. Feds like to call it "oxygenated fuel" with a myriad of additives. More oxygen molecules per unit of liquid fuel equals less combustion capability thus requiring more fuel to attain acceptable volumetric efficiency and power output. You may not have noticed, but your car is suffering the same problem. A ten percent drop is normal.
 

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Some Guy said:
Has the ambient air temperture changed recently? Vehicles tend to get poorer mileage in cold weather.
Cold weather in Florida :jsm: - Al Gore begs to differ!!!! :smoking:

Folks down here bundle up and break out the sled dogs when it drops into the 60's (15.5+ C). :)

Tom
 

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TPadden said:
Cold weather in Florida :jsm: - Al Gore begs to differ!!!! :smoking:

Folks down here bundle up and break out the sled dogs when it drops into the 60's (15.5+ C). :)

Tom
Hey, Florida is a big place. I have been camping in florida when it dropped into the the high 40's, thats enough to have a negative effect on gas milage.
 

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Some Guy said:
Hey, Florida is a big place. I have been camping in florida when it dropped into the the high 40's, thats enough to have a negative effect on gas milage.
Yep - and I've seen snow in Pensacola. That's why they call me a snowbird :D !

Tom
Weeki Wachee Fl.
Gainesville, Mo.
 

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Discussion Starter #12
^^ Thanks for that. Help to know now when I goto fill, NOT to fill to the neck bottom.

As far as temp, it's all over the place here at the moment. In the mornings at 430am (when I goto work), it's in the 40's, but by the time I get out of work at 1-2pm, it's 75 degrees outside. Give or take 10 degrees on either spectrum of the day.

But last year, when I rode the beast to work around this time of the year (I bought her on April Fools), I noticed no matter what, 100 miles before the light came on. now, it seems I'm lucky if it makes it to 95-100, as it usually comes on around 85-90, no matter how aggro or passive I drive.
 

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This is just input so as to point out there can be a lot of different causes to some things & sometimes not just a single cause either come to think of it..........

Quite a while ago I got asked to have a look at a 750 Brute that was getting bad fuel mileage(well a couple actually) but it was being looked after by dealers to keep the warranty up. I thought/felt it was way riche right across the whole map, you could smell & feel it when u road it & the tips of the exhausts were really black. A mate(Dealer) put his best race bike Merc on it & he did what I would have at the time to, & lowered the TPS setting to lean it & get it running better. But even then I felt it wasn't at it's best on the road, just didn't have the edge others I'd ridden had but I couldn't put my finger on it(not enough time). Now it was hard to know if the bike had changed or not over time because it was a new owner so no other feed back.
Now the funny thing is, this bike had low Kms on it & is the one I found the coils going bad on with corrosion(posted ages ago). So I should have been sus to the other, "now" EX, dealer who had been looking after the bike. But we weren't in a position then to try to trace the possible cause of this tuning event.
Well ! in hindsight I should of taken on the bike totally back then & spent the time, But I got a second shot at it a short time later & found nearly a full rack of exhaust shims loose/outta spec, therefore not getting full cam lift to the valves, which was limiting the engines ability to make the most of it's fueling before & I think is what had caused the first problem.
As soon as those shims were all adjusted into spec, the bike was lean right across the map & had to have the TPS put back richening the fueling again. The bike gets approx. the same as all here get now on a tank full & runs in my opinion & the owners SWEET & sharp !

Best thing is to start simple & be logical when trying to track something down like this really. (plug gaps, earths, wheel bearings binding, etc. etc. )

PS...but we here in Aussie also(as above) get better mileage outta our Premium fuel than the normal std. unleaded too. So fuel mixtures are a factor in this changing time. Pity the Premium gums up the valve train unless u ride around a 10/10ths all the time "A". :)
 
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