Gas mileage dropping slowly

Alb brajn · Post by **Alb brajn** » Tue Feb 28, 2012 3:05 am

For the first 7 months of riding my buddy the mpg stayed pretty steady at around 92-93 mpg. Now over the last four it has been slowly dropping. My average has just dipped below 90 and none of my tanks in the last 4 months have been above 90. Have any of you experienced this or know what the cause could be? I worry it could be a sign of something bigger.

Cheshire · Post by **Cheshire** » Tue Feb 28, 2012 3:29 am

Immediate thought: winter formula fuel.

What's your mileage?
Oil change interval?
Services kept up with?
Etc.

Data, we needs it.

Skootz Kabootz · Post by **Skootz Kabootz** » Tue Feb 28, 2012 3:49 am

My mpg generally drops when I am in need of an oil change or service. Improperly inflated tires is another cause.

Alb brajn · Post by **Alb brajn** » Tue Feb 28, 2012 3:55 am

I currently have 2,877 miles under our belts, with a dealer service at 500 miles and a self performed oil change at 2500.

2wheelNsanity · Post by **2wheelNsanity** » Tue Feb 28, 2012 5:24 pm

My fuel milage is slowly decreasing, its irradict to put it mildly. My fluctuations could be associated with another issue I have which is possibly EFI related. However, I have come to the conclusion that these engines are so small that minor changes in the weather can affect perfromance. Others have noted that winter fuel could be to blame for milage drops. At 480 miles I started keeping tract of my mpg, here it is from my excel file.

Slink · Post by **Slink** » Tue Feb 28, 2012 6:06 pm

any chance you feel like sharing the excel spreadsheet?

Syd · Post by **Syd** » Tue Feb 28, 2012 6:09 pm

Could it be that as you are getting more comfortable with your Buddy you are twisting the throttle just a bit more?

Raiderfn311 · Post by **Raiderfn311** » Tue Feb 28, 2012 6:35 pm

^^^^Very strong possibility!!

SkutiJo · Post by **SkutiJo** » Tue Feb 28, 2012 7:02 pm

Syd wrote:Could it be that as you are getting more comfortable with your Buddy you are twisting the throttle just a bit more?

That's definitely a possibility, but even changes in stop-go traffic can account for changes in performance, as can tire wear, belt/trans slipping, etc.

TVB · Post by **TVB** » Tue Feb 28, 2012 7:03 pm

The tank-to-tank variation is just how the universe operates: that extra splash you put in one time lets you go farther on that fill-up, then the hasty cut-off the next time leaves you a little short.

My gas mileage the first couple fill-ups was over 100mpg, and I've never gotten close to that since. I figure it was because I was afraid to go over 30mph at the time.

bgwss · Post by **bgwss** » Tue Feb 28, 2012 8:50 pm

I know my mpg goes down when it gets colder as it takes longer for the bike to get to its sweet spot in the morning. Weather warms up my mpg usually goes up as well. Also wind can effect it as well, had 46 mile an hour wind gusts the other day.

kmrcstintn · Post by **kmrcstintn** » Tue Feb 28, 2012 9:34 pm

lots of factors...fuel formulation change for winter months, carbeurator deposits, age of oil in engine, wind buffeting, how hard the operator is on the throttle, condition of fuel, cold starts, how much fuel you put in, tire pressures, amount of weight being carried, et al

I try to treat each tankful with ethanol treatment with occasional fuel system cleaner; now that I am about to start filling all my gas cans, I will treat every can with an appropriate amount of seafoam & ethanol treatment as a 'maintenance dose' with intermittent higher doses of seafoam or other cleaner every few tankfuls to keep the fuel system clean

BootScootin'FireFighter · Wed Feb 29, 2012 12:38 am

I've noticed it, but only been tracking fuelly for about 6 months. I've dipped down to the mid 80s from the mid 90s, so maybe it's winter formula, although I've never heard of that before. I also have been making shorter trips, which could play a role. I'm due for a major spring cleaning here shortly, changing all fluids and filters, thorough carb cleaning, new plugs, new sliders and belt, and a seafoam flush as well. I might even fully drain the fuel tank as well. Hopefully that makes a difference.

Post by **ericalm** » Wed Feb 29, 2012 4:20 am

2wheelNsanity wrote:I have come to the conclusion that these engines are so small that minor changes in the weather can affect performance.

Indeed! They're so small that changes to any variable can affect gas mileage and performance. Adding a top case, windshield, a couple psi difference in the tires, overdid it on pizza last night…

PeteH · Post by **PeteH** » Wed Feb 29, 2012 12:42 pm

Yeah, there are some days when the Buddy just feels 'sluggish', like it didn't want to get out of bed in the morning, and I start thinking about fuel, wind direction, tire inflation, junk in the fuel, my weight, what I'm hauling, ethanol in the fuel, humidity, temperature, winter blending of fuel, etc....

But then come the days that are just sublime, where the Buddy responds to the gentlest twitch of the throttle without a cough or hesitation, and you know it's breathing and drinking just right. The wind is at your back, and you go on a longer ride at that sweet-spot of speed, and when you get to the gas station you find you've touched 100mpg.

BuddyRaton · Post by **BuddyRaton** » Wed Feb 29, 2012 12:51 pm

Don't forget gasoline responds volumetricly with temperature. If you fill up when it is cold you will get denser thus more mass of gas than when it is warm. If you're hanging around 90 mpg you got nuttin' to worry about.

That and all the other little stuff people mentioned plus at 2,500 miles the motor is finally getting well broken in and loosening up.

Scooterboi · Post by **Scooterboi** » Wed Feb 29, 2012 1:57 pm

And don't forget altitude, especially for carburated engines. My mpg is always in the low 80's and top speed is around 55. EFI can get some of the performance back but it will never run like it does below 2000 ft.

Alb brajn · Post by **Alb brajn** » Thu Mar 01, 2012 1:42 pm

Lever thought of weather and such have that big of an effect on gas mileage. I think I will keep tracking it and see what happens.