Gas mileage - 32mpg ok? What speed?

[alvald83]

Hello guys,

I know this topic has been gone over, but i just wanted to know how fast people are going to get they're mileage.

Yesterday, i did a 480 round trip ride and got around 32mpg (80-85 mph freeway driving). Is this acceptable mileage? I know that i could improve that by slowing down, which i plan to do on my longer ride.

Since i am still planning on doing this California to Louisiana trip in April, i want to make sure that i am getting the best possible mileage on my '83.

I changed the spark plugs and wires earlier this year. I know tire pressure is important. What else do i need to do to make sure i am getting the best mileage possible? I hear people getting mileage in the 40's, is that just because they are driving 60 miles an hour? Just Curious? Thanks Al

[Trevor Heath]

Surely properly tuned you should be able to get 40-45 mpg at 70 mph

 

But yes, "the power needed to push an object through a fluid increases as the cube of the velocity. A car cruising on a highway at 50 mph (80 km/h) may require only 10 horsepower (7.5 kW) to overcome air drag, but that same car at 100 mph (160 km/h) requires 80 hp (60 kW). With a doubling of speed the drag (force) quadruples per the formula. Exerting four times the force over a fixed distance produces four times as much work. At twice the speed the work (resulting in displacement over a fixed distance) is done twice as fast. Since power is the rate of doing work, four times the work done in half the time requires eight times the power."

[Snaggletooth]

Speed is your culprit here for sure, but you can get a bit better than 32. Pushing the bike on the big road fully loaded I can drop to low 40's. Getting agressive with the throttle anywhere will take me down to 36 or lower at times.

 

My personal best for a long, easy ride going through 3 tanks of gas on the backroads in the 60-65 MPH range gave me 48 MPG.

 

So many things can effect your MPG. Speed, head winds, load, air filter and carb adjustments. Even the size of the wind screen will have some effect.

 

I'd start with looking into the carb adjustments and condition. Most likely improvement will probably be there. Even a carb sync.

 

Mike

[jasonm.]

32mpg @ 80+mph is not poor. Also there are many variables...weight of you and how you are loaded? is your rear tire inflated correctly- aka near max for high speed riding? 48mpg is not a typical high. Most see 40mpg or so at speeds 65mph or less trolling along in 5th gear back roads. I suspect Snaggletoooth has shimmed his needles...to a very lean setting. I get 35-37mpg at the same 75mph+ speeds...aka always above 75mph for long periods. But you should never get below 30mpg unless pulling a trailer. 1st-Try a back road ride keeping it in 5th whenever the speeds are 45-65mph. Then you should see an easy 40+mpg. If not, then shimming the needles to compensate for worn needle jets may help, does help. Do a search for "shimming" or shims.

Edited December 4, 2011 by jasonm.

[Prairiehammer]

Al,

We did a 2800 mile circumvention of Lake Superior this past August on my 1990 VR. All two up, loaded with camping/sleeping gear and everything needed for two weeks on the road. We rode Interstate at 75-80 mph, state/provincial roads at 60-65, county roads at 50 mph; a bit of everything. Even a 101mph jaunt with Yooper (the bike handled that quite in stride, but I started experiencing sharp pains in my back.) http://www.venturers.org/Forum/images/smilies/no_no.gif

I averaged 42.1 mpg for the entire trip. We recorded a high of 44.3 and a low of 39.1.

The high was on two lane (Trans-Canada 17) from Terrace Bay to Kakebeka Falls, the lowest from Two Harbors, MN to Ashland, WI. (traffic congestion, bumper to bumper at paddling creep but my bike was acting up and was revving at highway speed while barely moving).

I have found that anything over 80mph lowers the mileage severely. I believe it is related to aerodynamics; engine rpm doesn't seem to make as much difference. Two-up at fifty-five mph with a 25 mph headwind causes my mileage to drop precipitously, just like when I am running 80mph. Then I get 37 mpg. Sixty-five mph with a twenty mph headwind and I got 37.

Having said all that, your mileage seems low. My '83(s) usually got in the 50-53 mpg range on the Interstate at steady cruise, although not at 80-85mph.

[Venturous Randy]

After shimming my needles, I have gotten around 48 several times two up and running back roads. I believe shimming made the bike run better and took away a lot of the idle rich smell. I recommend it highly.

RandyA

[First_N_Last]

Hi Alvald;

 

During my 5800 mile tour in June, I rode a lot at 75-85 with a load of gear. With my full windshield & a corrected speedometer I got right around your mileage with a 2008.

 

I got a little better mileage when I had done the D-Cut in the air intake, but it leaned it out too much & took away from power at high speeds. I restored the intake to factory.

 

JohnB

 

Hello guys,

I know this topic has been gone over, but i just wanted to know how fast people are going to get they're mileage.

Yesterday, i did a 480 round trip ride and got around 32mpg (80-85 mph freeway driving). Is this acceptable mileage? I know that i could improve that by slowing down, which i plan to do on my longer ride.

Since i am still planning on doing this California to Louisiana trip in April, i want to make sure that i am getting the best possible mileage on my '83.

I changed the spark plugs and wires earlier this year. I know tire pressure is important. What else do i need to do to make sure i am getting the best mileage possible? I hear people getting mileage in the 40's, is that just because they are driving 60 miles an hour? Just Curious? Thanks Al

[jasonm.]

After shimming my needles, I have gotten around 48 several times two up and running back roads. I believe shimming made the bike run better and took away a lot of the idle rich smell. I recommend it highly.

RandyA

shimming needles will NOT fix a rich idle issue. Rich idle has two common internal carb causes that happen slowly . 1)float/fuel level too high and (2)leaking choke plungers. Choke plunger issue is due to today's ethanol causes corrosion(water) in the plunger's aluminum cylinder assy. and results in poor sealing. Floats go bad also from the ethanol attracting water. Our plastic floats do not like water.Which causes them to soften and sink. I have seen these issues. I solved my rich issues after resolving these two causes. Regarding MPGs where you live is important. I live in a very hilly area. 20%+ grades are commom on every road, every mile. There is no such thing as a Flat & level around me. FYI, I have been to most every U.S. state. So area around the great likes would likely cause my MPGS to jump up.

Edited December 4, 2011 by jasonm.

[greg_in_london]

I ran a long thread a couple of years back and surveyed quite a few people.

 

Bottom line seemed to be that some people had thirsty bikes and others didn't, but how people ride and tune their bikes has an impact as well. A thirsty bike always seemed to drink more than an economical bile, no matter how they were ridden - from what people said, but a thirsty bike used fast and hard would empty the tank while you watched, while others claimed 200 miles to a tank (or more !) when going steadily.

 

[EDIT] Here it is - http://www.venturerider.org/forum/showthread.php?t=20950 [/EDIT]

Edited December 4, 2011 by greg_in_london
Adding link

[longrider805]

Mine must of been one of those "thirsty" bikes, I adhered to every trick on this forum, not to mention the money spent on choke plungers, metering needles and needle jets, diaphrams, new floats, valve adjustments, Ignatech CDI's, blah, blah, blah. I actually got 39 mpg one day with a heck of a tail wind, in a part of Texas where there is no uphill. When I rode home against the wind, that turned into 28. These bikes were designed and manufactured when gas was less than a buck a gallon. They didn't CARE about fuel economy. Thats why they hauled A**. Sorry, just my 2 cents................

[Venturous Randy]

shimming needles will NOT fix a rich idle issue.

 

So you are saying there is no fuel flow at idle around the needle and jet?

RandyA

[jasonm.]

So you are saying there is no fuel flow at idle around the needle and jet?

RandyA

 

 

that is CORRECT. Because the throttle plates(butterflies) are closed and thus drawing fuel mixture thru the idle jet system. Which is on the engine side of the throttle butterfly. Flow around the needle on these begins @2500rpm or so. But if your floats are way off...then it will draw fuel past the needle the second the throttle is opened. What people often smell when leaving a stop can be fuel levels too high in the bowls and a back draft when moving slow. Especially on a 1st gen . I replaced all my floats , float needles and $400+ in other carb parts this year. Quite a learning experience. Due to the ethanol fuels mine runs lean in the middle but not too lean(EGA said). But for some reason is rich past 6000rpm full throttle...even with new needle jets. ... But this is where I really do not spend much time anyway.

Edited December 6, 2011 by jasonm.

[Guest tx2sturgis]

But yes, "the power needed to push an object through a fluid increases as the cube of the velocity. A car cruising on a highway at 50 mph (80 km/h) may require only 10 horsepower (7.5 kW) to overcome air drag, but that same car at 100 mph (160 km/h) requires 80 hp (60 kW). With a doubling of speed the drag (force) quadruples per the formula. Exerting four times the force over a fixed distance produces four times as much work. At twice the speed the work (resulting in displacement over a fixed distance) is done twice as fast. Since power is the rate of doing work, four times the work done in half the time requires eight times the power."

 

 

Huh?

[jasonm.]

Trevor, what does that have to do with the price of tea in China?

[Shamue]

I track my fuel quite a bite, and compare speed to fuel milage.

Have found my 2008 RSV get 40 to 42 mpg at a average 65 mph two up on flat land or mountains.

At 70 to 77 mph average my mpg drops to 37 to 39, 2 up flat or mountain.

At 80 to 85 mph average my mpg drops to 35, 2 up flat or mountain.

Now here is the puzzle, I have had to make a couple of long interstate runs of 1000 to 2000 miles and was cooking at between 80 and 90 mph and mpg dropped to and average 27 mpg.

I thought running that fast I would be out in front of everyone on the interstate, but I still had semi's passing me and several like I was the one standing still.

I do feel after 50,000 miles I have a good gauge for how far I'll get at the speeds I usually travel.

Always keep the carbs tuned and this pattern continues to repeat it's self.

Pulling my trailer with gear, total weight approx 350#, 2 up another 400#s I stay around 70 mph and get an average 39 mpg.

Have gotten 50 mph riding the Blue Ridge Pkwy and a few other long senic runs.

[jasonm.]

I track my fuel quite a bite, and compare speed to fuel milage.

Have found my 2008 RSV get 40 to 42 mpg at a average 65 mph two up on flat land or mountains.

At 70 to 77 mph average my mpg drops to 37 to 39, 2 up flat or mountain.

At 80 to 85 mph average my mpg drops to 35, 2 up flat or mountain.

Now here is the puzzle, I have had to make a couple of long interstate runs of 1000 to 2000 miles and was cooking at between 80 and 90 mph and mpg dropped to and average 27 mpg.

I thought running that fast I would be out in front of everyone on the interstate, but I still had semi's passing me and several like I was the one standing still.

I do feel after 50,000 miles I have a good gauge for how far I'll get at the speeds I usually travel.

Always keep the carbs tuned and this pattern continues to repeat it's self.

Pulling my trailer with gear, total weight approx 350#, 2 up another 400#s I stay around 70 mph and get an average 39 mpg.

Have gotten 50 mph riding the Blue Ridge Pkwy and a few other long senic runs.

Semis passing you. Simply...your speedometer is very optomistic.As with most bikes. But your mileage is good ...considering you are possibly overloading your bike. EX: Mine 85-90mph constant across Nebraska pulling a trailer w/gear=#200# = 28mpg. Crossed the state in about 7 hours w/stops.ALL Your MPGS are the same as mine. So we are both in the "same boat". But I have never seen 50mpg in the 20+ years I have owned this 87VR 20= yrs. Guess it's the bigger carbs and a true 90+hp at the rear wheel.

Edited December 9, 2011 by jasonm.

[Shamue]

Semis passing you. Simply...your speedometer is very optomistic.As with most bikes. But your mileage is good ...considering you are possibly overloading your bike. EX: Mine 85-90mph constant across Nebraska pulling a trailer w/gear=#200# = 28mpg. Crossed the state in about 7 hours w/stops.ALL Your MPGS are the same as mine. So we are both in the "same boat". But I have never seen 50mpg in the 20+ years I have owner this 87VR. Guess it's the bigger carbs and a true 90+hp at the rear wheel.

I sure it's the 30 to 50 mph speed limit for most of the national park roads and not being in a hurry that gets me that milage. It's the only time the RSV has been able to do it and has only happened a few times.