Poor fuel economy HELP!

1982 XJ1100
carbs squeaky clean
new k&n pods
4-2-1 header
30mpg highway
changed jets
30mpg
changed timing
30mpg :?
70 mph
30mpg 8)
50 mph drafting semis @ 1 second following distance
30mpg :?
hot weather, cold weather
30mpg :?

I tried restricting the exhaust (overscavenging?)
will let you know :?:

someone said they're getting 48mpg highway
what am I doing wrong?

thanks in advance
TECHLINETOM :? :cry: :x

 

How high are the floats in the carbs?

 

They are set to spec. A little bit (3-4mm below gasket)

restricted exhaust
30mpg :? :cry:

plugs are a little darker than a grocery bag

tried adjusting the pilot screws
was too lean and wouldn't get off the line
richened it some helped the bottom end
still pops lightly @ no load 2500-5000 rpm
synced the carbs got better low end
no effect on milage

drilled an extra set of pilot jets
best drivability yet still no change in milage
i think i will try opening up the emulsion holes in the needle jet ( ahve an extra rack of carbs for parts so I can go back at any time)
I might also try shimming the slide springs to slow them down a bit.
I'm doing one change at a time so i can test it.
thanx,

 

Have you checked your odometer for accuracy?

 

I think 48 MPG is high for the 1100, mid to upper 30's would be more realistic. Remember, pods pull more air AND more fuel! Recheck float height and your speedometer/odometer for accuracy.

 

will double check odometer today

 

Just a thought- - I heard the XS-11 had a vacuum advance. . . does your XJ-11 have that feature, and is it working?
This was supposed to improve fuel economy, and was an unusual feature on bikes in 1978.

 

The XJ1100 has a solid state TCI, no vacuum advance.

 

not carrying extra weight like saddlebags, fairings, or mother in laws are ya?

 

Not exactly any more! 8)
I replaced the ignition with a 79 xs1100 pickup and advance and I am using two GM HEI modules and 2 GM two output coilpacks.
My tci was bad and I replaced the whole shootin match for less than $100.

 

I have a small Shoei fairing. No saddlebags or mother in law in tow. :wink:

 

Odo is accurate.
Middle gearbox was almost dry!!!
Had what looked like metallic grey paint in there!!
Who drained out my Royal Purple gear lube?

The drain plug fell out about 3 months ago.
After 3 days it locked up!
I refilled it with more Royal Purple and it has been fine ( or so I thought).
I drained it last night and flushed it.
I guess I will refill it and start looking for a new one. :cry:

 

Yup working fine.