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How to improve gas mileage from 32mpg

  • Thread starter Thread starter armstrong
  • Start date Start date
A

armstrong

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Hello I have a GS750 1976 and have cleaned carbuators and replaced and went through the over head cams and changed oil and filter, replaced the fork seals with new oil and new air filter and new fuel pitcock and new tires and still can not get anything but 32 mpg. I hope someone can help as I would sure like to improve the mpg, I just spoke to a man riding a Honda 750 1981 and he is pulling 83 mpg so any help please respond, thank you.
 
I'd put money on that guy being a liar...


I've gotten mid/low 30's on my 750 before, with some, um... "spirited" riding. Usually get around 40.

Have you checked your valves?
 
change your gearing; go smaller in the rear or larger in the front. Try searching threads for gearing, there might be some suggestions!
 
armstrong said:
Hello I have a GS750 1976 and have cleaned carbuators and replaced and went through the over head cams and changed oil and filter, replaced the fork seals with new oil and new air filter and new fuel pitcock and new tires and still can not get anything but 32 mpg. I hope someone can help as I would sure like to improve the mpg, I just spoke to a man riding a Honda 750 1981 and he is pulling 83 mpg so any help please respond, thank you.
Click to expand...
He's DEFINATELY a liar. If he's pulling 83 mpg then he's not going to be running long because the bike is lean as hell. YOU need to check your jetting. What colour are your plugs? how does the bike run? What size sprockets are you running? Etc etc etc. There are MANY variables involved in fuel economy on these bikes. Small, seemingly insignificant changes can change fuel mileage drasticly. So can the amount of wrist you put into the bike. I can manage around 45MPG, two up, cruising at 65mph on my 1100, with the stock gearing. Bump the teeth down a couple on the rear sprocket, and ive squeezed out 50MPG on the highway at 65. At 75MPH, my fuel economy goes down as much as 10mpg. The 8v motors arent QUITE as efficient as the 16v motors, but 32mpg is still a bit too low. Check your pilot circuit ie your air and fuel screw settings. This is where MOST people who cruise spend most of their time in the carbs. This is also the circuit where a small change can have a large effect.
 
I just spoke to a man riding a Honda 750 1981 and he is pulling 83 mpg
Click to expand...

No way he's getting 83 mpg out of a 750, maybe 38 mpg. It's pretty common to get in the high 50's with a 550cc but the 750's usually will get low to mid 40's.
 
After I cleaned the carbs I had a motorcycle shop mercury sink the carbs and the man said to do the overhead cams so I did them. He said timimg as well but I have not done that yet, the spark plugs are three years old now and one was dark oil looking.
 
Well THAT guy at the shop did you no favors. Ideally, sync should be performed AFTER a valve adjustment, as adjusting the valves will have effect on vaccum pull. So basicly he took your money, because now your sync might be a little off. When you say the plug was dark. Was it oil or gas? Oil will be black and shiny, gas will be black and fluffy or chalky. If you are burning oil, you have other problems to deal with than fuel mileage. If youre too rich, and the plug is gas fouled, that will explain part of your problem.
 
The spark plug was oil as it was wet and wiping it with a rag it cleaned up quite a bit, yes so the vacuum is off but oil probably bigger issue.
 
83 mpg

83 mpg

I have a friend, a reliable source, that can claim near 80 mpg with his Honda Rebel...but only if he goes to extreme measures to improve mileage. He will kill the engine as he's coasting down hill or coming to a stop at a red light. Then he'll roll start it if it's a hill or use the electric starter to restart it as the light turns green.

And I believe him when he claims in the low '80s. But that's a 250cc Rebel, and doing things I'd never do just to save a few pennies in gas. He also admits that it's very rare that he gets that kind of mileage because he rarely goes to those extreme measures.

80MPG on a 750? Sorry...I don't buy it.
 
LarryA_Texas said:
I have a friend, a reliable source, that can claim near 80 mpg with his Honda Rebel...but only if he goes to extreme measures to improve mileage. He will kill the engine as he's coasting down hill or coming to a stop at a red light. Then he'll roll start it if it's a hill or use the electric starter to restart it as the light turns green.

And I believe him when he claims in the low '80s. But that's a 250cc Rebel, and doing things I'd never do just to save a few pennies in gas. He also admits that it's very rare that he gets that kind of mileage because he rarely goes to those extreme measures.

80MPG on a 750? Sorry...I don't buy it.
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my mothers 250 rebel gets 75-80mpg
just filled it up the other day for her, $3 to fill it up haha
 
Liar????

Liar????

I wouldn't be so rash as to call the '83 MPG Honda guy' a liar^o. I don't think there's a chance in the world that he's correct but, geeee, can't we be a little more charitable than that???:-k

A lot of people get terribly mixed up when it comes to simple math so let's lighten up a couple of notches; I'm sure he meant no harm.;)
 
I have had odometers that ring up a lot more miles than they should, this may be part of his math error. I would believe 50 something, 60 possible, yeah maybe, but not 83.

On the other hand, if anyone made a bike that was designed from the bottom up to be efficient instead of fast, they could do this easily.
 
I would bet it is just a typo 38 mpg is realistic for a 750. I would turn the fuel screw in about 1/8th a turn - screw on the bottom. Should be 5/8ths turn out from lightly seated. Finish tuning with the air screws on the side of the carb. When I ride some what conservatly I can get 36-38 mpg. I have got as low as 25 when working the gears.
Which plug is black ?? #3 would indicate poss bad petcock. Also check your coil voltage-weak spark can effect milage.
 
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I get 65-70 mpg on my 250 Nighthawk, which is essentially the same engine as the Rebel. My 650 Nighthawk gets about 50, and my 750 GS gets about 40. I doubt a 750 can get 80+ mpg without being trailered.

Oh, and my 1.9L Jetta TDI gets a consistent 43. :D
 
:-\\\
Getting back to the question at the beginning, you want to increase your mileage, stock airbox, stock exhaust and don't whack it wide open and run it to redline:p
OK, whack it open and redline it once in a while and you can still get decent mileage.

Tune it up check the mixture to see if it is rich and you should get up higher.

:-$I get 60mpg on my bike but it has to be on the highway at a steady speed that is how I get up there.
 
armstrong said:
The spark plug was oil as it was wet and wiping it with a rag it cleaned up quite a bit, yes so the vacuum is off but oil probably bigger issue.
Click to expand...
Ok, let me be a little bit more clear. If its oil, USUALLY wiping it with a rag wont clean the plug off very well. If you pull it, and its wet and black, let it dry out. If it dries and its still shiny, its oil. If it dries and its black and fluffy its gas. Either way, the bottom line is you have something that needs attended to, but you'll need to figure out which it is. I would hate for you to go chasing a valve seal leak or something of the like when the bike was simply rich on the one cylinder.
 
I used to get an honest 65 mpg from my Kz750 twin. On my 1100 I get a little over 40 on the highway but it drops into the 30's on the back roads in lower gears and higher rpm.
 
To be honest, you can tune these things thru gearing and carburetion to get really amazing mileage for bigger CC machines, but at the expense of enjoyment IMO. I honestly dont care how many MPG i get unless its the bike ive set up for commuting. Its STILL getting better than any car ive owned. Whats more important to ME is, as cheesy as it sounds, SMILES Per Gallon :D And my GSs have always gone above and beyond expectations there.
 
My 77 750 gets about 32 or so. Although I've never really checked it that good. I ride for the smiles and could care less about MPG. Of course my car gets 32 so i just drive it to work. Rush hour traffic on a 4 lane interstate is not my idea of having fun on a bike.
 
I was able to get 63mpg once out of a '82 650 Nighthawk, and 60 all the time. I've never been able to get too close to that with the GS700ES - high 50's a couple times, but mostly low to mid 50s depending on gearing.

That's all highway with a VERY judicious right hand - I can squeeze some mileage out of vehicles.
 
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