Fuel mileage

[Tat2demon]

Last year I averaged about 32mpg. I changed nothing but so far this year Im sitting around 22. Almost exactly 100 miles per tank. Thats almost all highway miles.

This last week I did nothing but to and from work. 2 miles out out 21.5 each day is in town. The rest is interstate running almost exactly 4.5k rpm.

Today I took it out and ran about 4 miles at the 4.5k. Chopped the ignition, and the plugs looked great. Got back in town, ran a mile or so at around 2k, checked and still looked good.

I don't have any leaks that I'm aware of. Ive checked the petcocks and fuel lines multiple times. Ive also checked the timing and vac advance.

Any ideas?

[DGXSER]

Have you checked your plug gaps??

I recall a local XSsive and I left from my house and filled up together. He was on an SG, me on an SH. We got about 50 miles or so out and he ran out of gas. I had plenty left. He had changed his plug gap trying to overcome some tuning issues. When we reached our destination another 40 some miles away, he reset his plug gaps to stock. He made it to his house, another 10-15 miles or so from mine, on one tank of gas. It can really make THAT much difference.

[donebysunday]

I've been setting the the gap at 28, BP6ES and BP7ES pilots set at 2.5 turns out, 120 mains on 81LH, stock air box w/K&N, stock headers straight through Dunstall style muffs. Thrashing the bike at 15-75 mph. I got 21 mpg. on a 40 mile run out, on the way back I took different back roads with 15-55 mph. curves and twisties, running nice and easy staying in the upper gears as much as possible, 39 mpg. Go figure ? The 2-3 plugs were white 1&4 were darker pink, very near sand. I've now adjusted the pilot screws to 3 on 1&4 and 3.5 2&3. Have not had a chance to do a long run since, maybe tomorrow ? What plugs and gap do you suggest Don for best performance and mpg. ?

[TADracer]

What plugs and gap do you suggest Don for best performance and mpg. ?

IMHO, if you are mostly stock then stay with the BP6ES which is the recommended plug. The BP7's are too cold in most instances and will not give the best performance at slower speeds. BP5ES plugs will run about 250 degrees hotter than the BP6's.

[kevxs]

this thread has me intrigued because my bike is running great but my mileage is less than stellar. I do all city driving and last season I was getting about 28mpg which is less than ideal, however this season I've been getting 25mpg and the last tank was 22mpg!! Kinda hard to justify owning a bike that gets worse mileage than my little SUV!

Anyway like I say the bike runs fantastic (at least at city speeds), a couple of the plugs looked a bit rich, i put the colortune on it and the while the color is orange at idle but immediatly goes to a nice blue as soon as the throttle is opened a bit. I don't know if thats a clue to whats going on here but as always I'm open to suggestions! I'll check my plug gap whenever I come across my feeler guages.

[Diskman01]

Nate- Try a different gas station? Maybe they are still running the "winter blend"? Also, make sure that you are not using that ethanol crap. The 87 octane at Shell makes my XS happy.

[donebysunday]

Last year I averaged about 32mpg. I changed nothing but so far this year Im sitting around 22. Almost exactly 100 miles per tank. Thats almost all highway miles.

This last week I did nothing but to and from work. 2 miles out out 21.5 each day is in town. The rest is interstate running almost exactly 4.5k rpm.

Today I took it out and ran about 4 miles at the 4.5k. Chopped the ignition, and the plugs looked great. Got back in town, ran a mile or so at around 2k, checked and still looked good.

I don't have any leaks that I'm aware of. Ive checked the petcocks and fuel lines multiple times. Ive also checked the timing and vac advance.

Any ideas?

So your getting good color, not like me ? Yet my mpg. varies from 21-39 depending on how I ride using 93 non ethanol. This is really getting interesting ? Thanks For the post ! We may get somewhere ?

[CaptonZap]

Two things are the main determinant of mileage. One is the state of tune of the engine, and the other is the change of velocity of the bike and rider.
Railroads get good mileage because of, among other things, they maintain a speed, and avoid stop and starts as much as possible. Every time you twist the throttle, you are using gas to change your speed. The faster you go, the more power is required to overcome wind and rolling resistance. The more often you stop or slow down, the more fuel it takes to get you back to where you were, speed wise.
Is your machine set up to factory specs? Have you personally inspected every part that can be inspected without tearing the engine apart, and comparing it to factory specs? Check timing with a timing light, check advance with the light and a vacuum gauge? Check output of the coils with a spark gap test, plug gap, etc? Float level, jet and needle sizes and positions, air filter condition. Velocity tubes in place?
Valve clearance, cam timing?
Any deviation from stock usually means a decrease in efficiency. It may sound "cool", but it takes fuel to make loud noises.

If you don't have a manual, get one, and it will spell out all of the values you should tune to. If you do that, and try to maintain a steady speed, I'll bet your mileage will get better.
Try to time the lights so that you don't have to come to a complete stop, and then slowly get back up to speed. You don't need to be on the tail of the car in front of you, you'll just have to brake when he stops at the next light. Fuel wasted.
These bikes are capable of 40 +/- mpg, so yours can probably do the same.

CZ

[TopCatGr58]

High mileage, the holy grail for the XS11!

I see that you have the HD clutch springs....but have you checked the settings for them at the engine. IF the frictions have worn a little, then the throwout pin may be too tight, and that can then cause clutch slippage even with HD springs...so resetting the throwout can ensure the plates are fully gripping and not slipping under load!

CZ posted many good tips on getting the engine in proper tune, simple things like dirty air filter, dragging brakes, low tire pressure, running at too high MPH speed. And yes, poor quality gas can cause problems, too much ethanol produces less energy. I run Ethanol 10 gas, but I also run premium because of my Wiseco big bore and concerns about knocking with the higher compression and burning holes in pistons! I only get around 30 mpg, but I like to twist the throttle ... that's why I ride an XS11. It's NOT a commuter for me, but my leisure "toy", so I play when I want to!

Hope you find the fuel sapper and correct it.

T.C.

[Tat2demon]

Thanks for the reply guys.

Im tearing it down tomorrow to start getting it ready for paint.

While its apart Ill pop in some new plugs and I think pull the carbs and wet set them. I just did a dry set last time. However I would think the plugs would show if the float was off.

Its not the gas. All I run is 87oct with no ethanol and the last 3 tanks have been from different stations/brands.

The last full tank was 100 miles, only 10 of which were in town riding. The other 90 were steady, relaxed interstate driving at 65-70 mph at 4.5k rpm so I cant imagine its driving style. I got the same crappy mileage on completely in town tanks.

The clutch springs were just put in. About 300 miles ago. I "refaced" the steels and frictions at the same time, along with adjusting both the clutch lever and throwout.

Ill have to check on the brakes. I had the front all taken apart at the same time as the clutch.

I would like to be able to give some kind of driving diagnostic to help pin down the issue but the bike runs like a raped ape. Ive test ridden a few bikes for a friend over the last week and my 11 has put every one of them to shame.

[BA80]

I get lousy mileage to and from work too Nate. I think it's from dodging morons on the road.

Normally I get 32 -36 on the highway. It's the stop and go, shift down, shift up that kills the mileage. Sometimes commuting I only get 90 - 95 miles before the light comes on.

Warm up times and enricher use make a big difference too.

OOPS I just noticed your riding a standard. How does your air filter look?

[Tat2demon]

Like new. Its a KN that I put on last summer. I think Ive only put 3k miles on it since I bought the bike.

[DGXSER]

What plugs and gap do you suggest Don for best performance and mpg. ?

Sorry for the delay in responding, been on the road away from my info. Stock gap is .7-.8 mm or .028-.032 in. I gap mine at .032.

[BA80]

Spark plugs should be set at the minimum gap spec when they are new because the gap will widen with wear. Just sayin'.

[donebysunday]

Sorry for the delay in responding, been on the road away from my info. Stock gap is .7-.8 mm or .028-.032 in. I gap mine at .032.

Thanks Don !
I had my plugs at 28. Did a midnight run last night on my 81LH named AFTER MIDNIGHT Nice and easy few curves minor hills 35-55 staying on National Ave out of Milwaukee 5 mi. to get out of town then no stops watched the lights in town came back with 45 mi. on, filled it, 1.75 gal. = 25.7, light on the throttle stayed in higher gears. I did better on the last trip in the twisties Something I'm doing or not doing Goin to get a new set of BP6ES and set at 30.