gas mileage

[windjammergump]

just put a wiseco 1179 kit in my 81 special...went thru the carbs before hand and everything is new...got bike back today rode it 50 miles on 8 dollars of gas (3.64 a gallon) and now on empty....thats 25 miles to the gallon..i fig it should be 40 to a gallon.....110 mains and 45 on the low side whats up to fix my mileage...????thanks for any sugggestions....i need them bad.............gump

[SFerinTEXAS]

No help here as I have not done the wiseco deal. But just for curiosity what was your mileage before? I got a reasonable 42 on my last XJ fill. Its all stock. + iridium plugs.

[jetmechmarty]

It might help to break it in a bit. Check the plugs for proper fuel burn. I'm in the low thirties with a stock bike. On a long slow cruise, I can get 45 mpg. If I run hard, it drops well into the twenties. My bike is pretty much stock.

[James England]

just put a wiseco 1179 kit in my 81 special...went thru the carbs before hand and everything is new...got bike back today rode it 50 miles on 8 dollars of gas (3.64 a gallon) and now on empty....thats 25 miles to the gallon..i fig it should be 40 to a gallon.....110 mains and 45 on the low side whats up to fix my mileage...????thanks for any sugggestions....i need them bad.............gump

Isn't an increased fuel consumption to be expected if one increases the cubic capacity of the engine? I don't get 40mpg from a standard XS1100 and I don't hammer mine either. I'd have thought a possibly enthusiastic riding style, coupled with a 7% increase in cubic capacity, on a 30+ year old bike with a dry weight of 560lbs or so (your weight to be added to that + luggage etc), would lead to 25mpg. Years ago, on my new one, driving very enthusiastically along a 200 mile stretch of motorway (as 19 year olds often do), I could actually see the fuel gauge move relentlessly downwards.

Although it's not generally praised as a fuel economy measure, I'd have thought you're now a prime candidate for the XS750FD modification. It would probably be a fuel saver for you, given the increased capaciy of the engine. You'd take 500+ rpm a minute off at around 60mph... more as you go faster.

[bikerphil]

See if your brakes are dragging a bit, JAT

[DGXSER]

May not bt the issue, but those 45 pilots are not stock, 42.5 is stock. What are your pilot air jets?

Make sure you check your plugs and the gap on those as well. Once went on a long ride with a fellow XSive, he was having some carb issues so he opened up his plugs to try to compensate. We went about 60 miles into our 100 mile trip before he ran out of gas, we filled up before we left. He reset the plug gaps before we came back, he made it home on the tank.

[natemoen]

You have a lot of extra friction going on inside a fresh engine after a rebuild. Give it 500 or so miles before you start wondering.

[ManagerMike]

Ditto on what Nate said, let it break in. However, I still find that my 78 will get around 40 mpg OR run like a scalded dog..... but not both.
Guess it just depends on the left side of my brain at the time of measurement........

Of course the 40 mpg calculation was derived during a long and careful (and unintentional) stint on reserve

[Poprock]

New engines need time to settle in. I have about 3000 on a new set of intake valves (OMP polished stainless) and the bike is running sweeter every mile. After a break in valve adjustment, it has leveled out nicely. Fuel consumption is speed related. It's 65 miles from me to the closest place to legally exceed 55, and i get from 34 to 36.5 running a 850 FD, Fairing, etc. With some tweaking, hotter coils, maybe some iridium plugs it might go up. Might try that some day.

[crazy steve]

..i fig it should be 40 to a gallon.....

A number often strived for and seldom achieved...

Truthfully, few attain that mileage, and numbers in the mid to high twenties aren't at all unheard of. The best I've ever gotten was 40 mpg, and that was only once. With a big-bore, I would expect a small loss, and until that new motor is loosened up, I wouldn't worry...

[windjammergump]

12.75 fill up at 3.49 a gall.....

filled tank to the hilt...got 80 miles to a tank of gas...just guesssing on the 25 mph ....a little over 3 gals..got me 80 miles...rode 200 miles and filled tank 3 times but had gas when i got home....my old bike was an 1100 and got 125 miles to a 3 gallon tank...but it did have some miles on it.....thanks GUMP

[TopCatGr58]

Hey Jammer,

I've got the same bike, same little big bore kit, some 16+K miles on the engine now. 4-1 pipes, Indy filters, otherwise stock setup..cams, carbs with 117.5 mains, 42.5 pilots, I do have high output coils, OEM final drive.

The speed you're riding at has a definite influence on the mileage. On the superslab pushing a small windscreen, my 220lbs, rectangular saddlebags at 70mph, and it gets consistently 30MPG. Surprisingly this weekend at the XS East 2011 rally in Western Virginia, running the twisties with just the windscreen removed, but more "Spirited" riding, rpm's in the 5-6k range but mostly in 2nd and 3rd gears at 30-50mph, I was actually seeing higher mileages rates closer to the 40mpg range!?

The WIND puts a tremendous load on the engine....the faster you go, more horsepower that's needed and the more fuel needed to develop that horsepower, so even though speed limits have returned to the 65-70 range over much of the country, I would bet if you did an experiment and ride at 55mph one time and measure vs. 70mph trip that you would find a much better mileage rate at the slower speed....but it's not as much fun, and takes a bit longer to get where you're going!? And as stated, after breakin, it'll improve also!

T.C.