1983 GS650L - Poor Fuel economy

[Wingsconsin]

I was pretty certain I had the carbs dialed in just right...I have followed all the papers and tutorials right down to the letter ..I am pretty sure...The bike starts fine, a little cold blooded..but runs great after a brief warm up..plenty of power with no stumbles.

However I have finally run it enough to get a feel for the fuel economy and find it lacking...I have burned through nearly 3/4 tank of gas for about 100 miles...That seems a bit much to me....If the tank is about 4 gallons and I have used 3+ I am getting low 30's MPG and that would seem pretty poor for this bike...Right ?

So - I think I need to re-visit the carbs and adjust more...The Idle mixture adjustment screws (the ones uncovered from the capped port) need a bit more tightening I believe...Yes..?

Should I turn them IN another 1/2 turn...?

I have not yet looked at the plugs.

[tom203]

If this is a "L" ,your tank has a massive 3.2 gallon capacity NOT 4. Don't guess fuel economy by basing it on fuel guage. Fill tank to edge of filler neck. go for long ride > 50 miles. When you return, fill tank back up to same spot as before- note how much you added. Bingo. I get about 50 mpg up and down hills here, but I'm a mellow rider!

[Badooka]

No doubt- if your losing that much MPG, your eyes should be burning from such a rich fuel mixture at idle. You should be doing much better than 30's.

[Wingsconsin]

Okay - things to think about...

If this is a "L" ,your tank has a massive 3.2 gallon capacity NOT 4. Don't guess fuel economy by basing it on fuel guage. Fill tank to edge of filler neck. go for long ride > 50 miles. When you return, fill tank back up to same spot as before- note how much you added. Bingo. I get about 50 mpg up and down hills here, but I'm a mellow rider!

Ahaa...With a tank of 3.2 gallons than I have only bruned about 2+ gallons which yields more like mid to upper 40's MPG..Much better me thinks...Time to go for a ride and get the actual number...

No doubt- if your losing that much MPG, your eyes should be burning from such a rich fuel mixture at idle. You should be doing much better than 30's.

Not really getting that problem...just a little when on choke (enrichener) as it warms up... I had number 2 too rich but made that adjustment and it seems better...but I need to do the math on the fuel economy...

(Picture is profile now)

[Toasty]

I was pretty certain I had the carbs dialed in just right...I have followed all the papers and tutorials right down to the letter ..I am pretty sure...The bike starts fine, a little cold blooded..but runs great after a brief warm up..plenty of power with no stumbles.

However I have finally run it enough to get a feel for the fuel economy and find it lacking...I have burned through nearly 3/4 tank of gas for about 100 miles...That seems a bit much to me....If the tank is about 4 gallons and I have used 3+ I am getting low 30's MPG and that would seem pretty poor for this bike...Right ?

So - I think I need to re-visit the carbs and adjust more...The Idle mixture adjustment screws (the ones uncovered from the capped port) need a bit more tightening I believe...Yes..?

Should I turn them IN another 1/2 turn...?

I have not yet looked at the plugs.

When I had an L tank on my 550 I would have to switch to reserve at around 120 miles, so you're not far off. I was getting high 40s and occasional low 50's.

[Steve]

If this is a "L" ,your tank has a massive 3.2 gallon capacity NOT 4.

I have seen 3.2 and 3.4 as the capacity, they are close enough it does not really matter much.

Just for reference, Carl, we were in West Virginia this past weekend. Mrs. Steve's bike is still in pieces, so she rode our son's "Rat Bagger". Yeah, it's not quite her style, but she managed. The bike has (cheap) pods and a pipe on it, and is jetted to match. In spite of all that, the two tanks that she took all the way down to REServe, were 54.7 and 57.2 mpg.

I don't remember if I have calibrated the fuel gauge on this bike, but it is acting as if I have. As the needle crosses into the red zone, it's time to flip the lever to REServe. Within a few miles of doing that, we put in 2.089 gallons. 114 miles the first time, 119 the second time.

Keep in mind that the gauges on these bikes are not quite as accurate as the one on your Wing, but they are predictable, especially if you take the time to calibrate it. I like to have it go to REServe as the needle goes into the red zone, regardless of how many gallons the tank holds. The reserve is usually about a gallon (always nice to measure it so you know for sure), makes it easier to judge what you have left.

Bottom line: you can't judge fuel economy by watching the gauge, you have to pump the gas and do the math.


.

[Wingsconsin]

Might not be so bad afterall

Judging from the responses thus far I am slowly coming to realize that I NEED to go to the station and buy fuel.

I have not yet turned the trip ODOMETER back as it matches the REAL ODOMETER for miles as this bike has so few miles on it - About 850 original miles as of last nights ride in the rain (no face shield, no windscreen + rain = ouch)

I was thinking it would be easier to remove the tank and re-tune the carbs if necessary when the tank was empty...But now it seems another tank of riding is in order.

My plan of action is this --
Take a last picture of the trip Odo and the Real Odo matching, Fill tank and reset Trip Odo, ride until fuel is used and DO THE MATH.

Hopefully a high 40's number -
Maybe more if I can resist the wrist twist a little...zoom...
(not easy on this bike)