Gas Mileage Problem?

My '81 750 Seca has been getting 38-41 for the past year (except for the past three weeks that it's been parked waiting on a fuse block replacement).

 

Checked the pilot screws and they were out 3-4 turns on all of them, so i put them back to 2 1/2 turns out. Drove and still no better on the gas mileage. I the only thing i havent done is do the floats because that screw is pretty much welded in there(broke two screwdrivers already). Can the floats being off cause the abundance of gas usage?

 

Yes. Although I would think it prone to flooding out at idle.

 

Thats what I am not getting is that it seams to be running ok. It will sit there and idle, goes down the road, but uses the gas. My drive to work is 40 miles one way and by the time i get home the tank is almost empty. Roughly 25mpg is all that I am getting.

 

Any clue as to what jet sizes you have in the carbs? stock I believe the pilot jet is a 40 and the main is a 120. If your main is larger than that I would say that would definately contribute to the poor fuel economy. Also what plugs are you running? Should be the NGK BP7es plugs gapped at .32 I believe. Please correct me if I am wrong guys. My 82 gets around 38 right now,but I have to rejet the pilots, as it doesn't Idle at all at 2.5 turns out. Previous owner put on a Mac 4 into 1 header and a K&N air filter on her. I have been trying to sort all that out since I got it. Living at 6000 feet really puts a new twist in it. Should get better after that. I will hopefully get that done in the next few days. I will post up and let you guys know.

 

Finally got the pilot jets, size 41 and installed them. sinked the cabs again and it ran worse. Plugs started fouling. nice black soot. Reinstalled the originals and all is back to normal. I believe I wil get some larger air jets for the top end of the carb and see what happens. I will post up and tell you what happens. Anyone need any 41 pilot jets? LOL

 

I guess I don't have a reason to complain. My XJ700 has sat for 4-5 years and got about 38mpg on the first tank I ran through (which included about 3/4 gallon of gas from when it ran last!) That was also with the old plugs and filter 8O , and haven't even touched the carbs (yet). I just put a new air filter and plugs in day before yesterday and noticed a difference in performance. I will need to get gas on my way home tonight, but think it will be at least somewhat improved. I'm thinking that maybe I shouldn't have read any of this string as I am feeling less motivated to dismantle, clean, and synch the carbs now 8)! I imagine I'll do it anyway sometime soon :cry: