Fuel Economy on a GS750

[TheNose]

Earl,

What kind of screwdriver do you use to adjust the fuel screws so accurately? (7/8 of a turn) I have a heck of a time getting a screwdriver in and trying to turn it while counting the revolutions. It always seems to slip off the head when I'm turning and then I've got to start over. Got to be an easy way to do it, I just haven't figured it out yet.

Terry

[earlfor]

Terry
It takes me about 5 minutes to disconnect the fuel lines, remove the airbox, undo the clamps and take the carb stack off. Maybe 5 minutes to reset fuel and air screws and another five to reinstall everything. I find its much easier and more precise to do it this way rather than standing on your head, mirror under the carbs, trying to shine a light in the right place and set everything with the carbs installed.
I just use a medium size jewlers swiveling screwdriver.

Earl

Earl,

What kind of screwdriver do you use to adjust the fuel screws so accurately? (7/8 of a turn) I have a heck of a time getting a screwdriver in and trying to turn it while counting the revolutions. It always seems to slip off the head when I'm turning and then I've got to start over. Got to be an easy way to do it, I just haven't figured it out yet.

Terry

[Anonymous]

Dom

yes after a 100 miles are so all plugs turn sooty black.....my carb setup at the moment is.......pilot air screw 3 turns out, fuel screw( the screw under the carb next to float bowl) 2 turns out...stock pilot jets, needle jet clip is 2nd from bottom clip, 102.7 mains....i had 100`s but it still ran rich but that was with the old coils......from 1/4 throttle to half throttle it hesitates, top end is great, i pulled the front wheel yesterday a few inches of the pavement

[TheNose]

Earl,

It takes me a bit longer than 5 minutes. I have been removing the gas tank. I guess that isn't really necessary. I may try removing the carbs like you suggest. Mine runs great and starts instantly, but the mileage is only about 33 mpg. Plugs are a little sooty. Thanks for the advice.

Terry

[Anonymous]

Re: Dom

yes after a 100 miles are so all plugs turn sooty black.....my carb setup at the moment is.......pilot air screw 3 turns out, fuel screw( the screw under the carb next to float bowl) 2 turns out...stock pilot jets, needle jet clip is 2nd from bottom clip, 102.7 mains....i had 100`s but it still ran rich but that was with the old coils......from 1/4 throttle to half throttle it hesitates, top end is great, i pulled the front wheel yesterday a few inches of the pavement

Could i talk you into experimenting with the needled--if all of your plugs get black then drop the needle 1 notch-i cured a similar problem by doing the same thing on my bike(i had to use washers--no notches you lucky dog) if it works the result may leave a lean spot when the carbs are coming totally off the idle jets and it will also go a bit lean when you slack off the throttle at cruise--((i like the soung and by watching my plugs i see no problem with heat from the temporary lean condition.

[Anonymous]

I have gotten as little as 40mpg and as much as 55 wwith my 1980 Gs750r...I do not ride easy..I am ON IT alsways

[Anonymous]

thanks dom ill try that but im going to raise the clip 2 notches because i allready had it in the middle.

[Anonymous]

I took a jewelers screw driver with a bit the right size and cut it to about 1-1/2" inches long and then cut a slot in the top that I could see. The screwdriver was knurled around the shank, so it still grips well to turn. Then to adjust my fuel mixture I loosen the tank bolt and lift it from the rear just enough to slide a 2x2 under. With the 2x2 resting on the upper bike frame the tank is raised about 3 inches, which for me is plenty of room to fit my hand in there and not only turn the screws, but see the notch I cut. I could do 7/8ths of a turn if that's what I needed to do. With this screwdriver I can get to 3 of the 4 carbs without raising the tank, but #2 is impossible with the petcock and clutch cable and vacuum hose all going to that area.

Cheerio,

Roger Moore

[TheNose]

Earl,

I adjusted my carbs like you suggested, 7/8 for fuel, and 1 3/4 for air. Rode about 45 minutes, checked plugs. Number 1, 2, 4 were perfect. Number 3 was just little rich so I opened the air up another 1/8 turn. Is this the right way to correct number 3 being rich? Or should I close the fuel screw? It had just a very little bit of soot on it.

I made the adjustment while the carbs were on the bike. I don't like having to disconnect the control cables. I made a "screwdriver" to make the adjustment. I think I will make one out of a jewelers screwdriver like Roger did.

Terry

[Anonymous]

milage

Last Wed. I coverd about 180 miles half of which was in 2,3, gear and the rest normal and did about 51 mpg and used about 4 oz of oil.........from 65 to 90 degree temps........

[Anonymous]

Perhaps now that I'm not riding along with the BRAKES APPLIED, I may start getting better gas milage myself...

One can only hope

Roger

[mcycle-nut]

I get about 175 km (about 108 miles) before I have to hit reserve on my '78 GS750. It has a Jardine 4 into 1 header and pod filters. I really don't remember where I set the carbs, but whenever I remove a plug, it is light brown. I ride it hard. Redline is no stranger. :twisted:

[earlfor]

I dont know that it would make much difference which one you change to make the mixture leaner or richer. I think probably leaving the fuel screws all the same would be best.
So I would tweak the air screw. Besides, the air screw is much easier to get to. :-) Seriously though, my choice would be to tweak the air screw.

Earl

Earl,

I adjusted my carbs like you suggested, 7/8 for fuel, and 1 3/4 for air. Rode about 45 minutes, checked plugs. Number 1, 2, 4 were perfect. Number 3 was just little rich so I opened the air up another 1/8 turn. Is this the right way to correct number 3 being rich? Or should I close the fuel screw? It had just a very little bit of soot on it.

I made the adjustment while the carbs were on the bike. I don't like having to disconnect the control cables. I made a "screwdriver" to make the adjustment. I think I will make one out of a jewelers screwdriver like Roger did.

Terry

[earlfor]

I've run my 79 750 down to where I had to switch to reserve once. I hit reserve at 175 miles with a gallon still left in the tank.

Earl

I get about 175 km (about 108 miles) before I have to hit reserve on my '78 GS750. It has a Jardine 4 into 1 header and pod filters. I really don't remember where I set the carbs, but whenever I remove a plug, it is light brown. I ride it hard. Redline is no stranger. :twisted:

[Anonymous]

Gas Milage

I got my 78 GS750 last week and on my first full tank I hit 168 miles before I had to switch to my reserve tank, that's about 45 mpg. But it needs a tune up, prior owner told me he was getting about 50 mpg when it was properly tuned.