23 mpg

[beechfront]

i've filled my bike three times since i've had it. seems to be running good, but on all tanks i've gotten 23 mpg. one of the
times i filled was after a 60 mile trip from lincoln to omaha - part of the trip was 60-65, part of the trip was 75-80. the other two were combination town/highway driving. i guess i'm thinking i should be getting better than this.

any thoughts?

[strom]

check carbs, valves, exhaust and air filter/s for leaks, check the ignition timing... or sth.. the springs at the pick/up coil, ruptures of the vacuum hose that runs from the carb (boot) to the pick/up coil....

LP

[skids]

Are the pipes or baffles in the pipes shot?

[sixtysix]

Here is a tip we are working on for improving milage as well as some info I added for my own bike.......

How to improve gas mileage
by Jerry Fields

This is a recurring topic. I have an XJ with Vetter Windjammer IV (tall windshield) and Vetter saddlebags. Here in AZ (home elevation at around 5,700 ft.) I get 33-34 mpg. At lower elevations I get a couple MPG more, 34 - 36 on average. This is in line with what many other owners get, so your mileage does seem a bit low at 25 - 27.

What to do about it.....

1. Put in new spark plugs of the right type: BP6ES. Check them for color; you should get a light tan on all 4 if the carbs areadjusted correctly. If not, adjust and synchronize the carbs.
2. Clean/replace air filter element. OEM only, no after-market unit available for XJ. On a XS you can replace with K&N, Uni or pods.
3. Check tire pressures, (Dunlop 32 PSI front, 40 rear)
4. Check the carb boots for leakage. Easiest way is to squirt starter fluid or WD40 at the carb boots with the engine running. If the RPM increases, the boots are leaking and will need to be patched (Black RTV sealant) or replaced. (Make sure the clamps are tight!)

More advanced options:

1. Clean carbs. Pay special attention to setting float levels.
2. Check/replace coils and/or spark plug wires. (See XS11.com for details.)
3. Check for dragging brakes. Clean both master cylinders, paying special attention to the 'spooge hole' that allows pressure to release from the lines. (Also a tech tip at xs11.com.)
4. Along the same lines, you may be have brake cylinder piston seals that are sticking and not allowing the pistons to retract, causing bake drag. Rebuild the calipers.

(Both 3 and 4 should be easy to diagnose. Check the temps of your rotors after a while riding without having to brake. If they to hot to touch and hold on to with a bare hand, problem is in the brakes. You may also consider replacing the 20 year old stock lines with Chris Rawson's stainless-steel variety.)

Final culprit could be a slipping clutch. If the engine revs up a bit (under load) but doesn't increase in speed, clutch is slipping. Adjust clutch cable, replace friction plates, or install new clutch springs. A common set-up is using stock Yamaha friction plates and Barnett springs. Consensus is to install friction plates and springs at the same time.

For most riding situations you should bet getting in the low to mid 30s, but don't expect high 30s at 70 MPH. I have gotten that high, but only at slower speeds.

Having said all that, there are a few people who report getting into the low 40s, but I don't think they have full fairings and saddlebags, or live at lower elevations where the engines develop more power.

Now for my own comments:

I Replaced a leaky petcock, it was sucking gas directly down the vac. hose and into the carb boot. (note if you pull the vac hose off and it is wet with gas then rebuild your petcocks),

Replaced the diaphrams and slides and needles (and emulsion tubes) in my carbs, the needles (or tubes) can wear out causing XSive fuel to get by at any given setting, also a bad diaphram will cause that one cylinder not to respond properly, replaced wheel bearings, new timing chain, new slipon mufflers (bad baffles can cause poor milage)

After all this I gained about 5 mpg......

Hope it helps should be posted soon to the tips section.

[Tex]

Thanks for the milage info. I consistantly get a low fuel light at 73 miles on the trip odometer. That is riding hills but surprosed me. Do you know how much fuel is left when the light comes on?

Thanks again for the tips.

[sixtysix]

Not sure think a special has a 4 gal tank and light comes on after 3 ~3.2 gals.

[Tex]

Thanks,
Need to get busy eliminating possible causes.

Tex

[nashville_bill]

Tex,

Did you ever find out how much gas is in tank when the low fuel light comes on? I have an '81 xs special and I have been getting low 30s for gas mileage and my light comes on at about 95 to 100 miles. I haven't been brave enough to run it very long after that because I have to turn the petcocks to reserve soon after the light comes on and I don't want to push the heavy thing.

Bill Murrin

[crunchbird]

Light comes on at 95-100 miles on my SG. I get 3 to 3.2 gallons at the next station.

I've gotten a little better mileage on sedate group rides, but not enough to make an emotional difference. Instead of stressing about running out of gas, I stress about the light being broken and then running out of gas .

[Dragonrider]

0.8 us gallons is the number that comes to mind for Special reserve (after you switch the petcocks).