Fuel Mileage

[Shovel Jockey]

New to these XS650's and this forum. Just curious what you guys are getting for fuel milage on a stock bike(or modified). My stock '75 is only getting 41-42 mpg. Runs great though, 11k miles, no apparent major issues, tires properly inflated, filters clean. Every so often the bike spits back through the carb. I live at 2500'asl and ride to 3500-4000 asl daily. I am running 87 octane 10% ethanol over a NGK BR8ES plug that stays pretty dark, problem there? I can get non-ethanol fuel but it's 25 miles away. Any thoughts? Thanks, JOE

 

[aldo5468]

I average about 50 mpg on fairly level terrain in SE Michigan about 600-700 ft asl - typically 50-mile runs, mostly on state / county rural hard surface roads. I use premium fuel - around here it's 10% ethanol.

 

[gggGary]

At that altitude slightly leaner jetting may be appropriate. BUT in South Carolina it's would be too easy to go to sea level and maybe hole a piston................. Hills and aggressive throttle use make 40 MPG a reasonable number. Are you SURE the carburation is stock? I have seen a bunch O strange stuff opening up "stock" XS650 carbs. Just last week a "stock" pods only 79 I opened up had 150 mains instead of the stock 135s. Mis-set float levels and leaking float valves can both cause excessive fuel burn.

 

[pamcopete]

Here is a chart of the results of several 70 mile runs with changes in the ignition system with each run. The course was mostly clear highway with very little traffic, 600' to 700' ASL, 70F ambient, tires inflated to 32 PSI, 55 MPH max speed and a 33 tooth rear sprocket on my '81/H with PAMCO ignition, stock BS34 carbs, EMGO Dunstal replica 27" mufflers and paper air filters.

Starts out with mileage that you can expect under those conditions but the mileage steadily improves with each change in the ignition system. Timing was set to stock timing and spark advance was also stock. The bike was filled up at the same pump after each run and the mileage was calculated. Notice that the mileage continued to improve even with the larger 135 mains, which are recommended for this setup.

Improved gas mileage also equates to more HP because the engine is running more efficiently.

 

[sreimer]

I get 50 - 55 with somewhat aggressive riding both city and highway.

 

[xjwmx]

I get 60 mpg on a 100 mi ride I take pretty often. A lot of it is hills and curves and I'm in 5th only about 3/4 or the time total. '81 stock carbs and jets, and 17/34. 'Tarded timing, 87 gas of unknown whatever composition, Mike's regular replacement coil for '81. BP7ES plugs. Spitfires tires.

 

[weekendrider]

Shovel Jockey you might get a little better mileage and "lighter" color on the plugs by switching to a 7. The manual recommends NGK BP7ES or Champion N-7-Y.
You don't need or want the resistor types (BR).

 

[retiredgentleman]

I get around 55 mpg, and thats riding up in the mountains. I've tried both regular and high octane and I can't detect any difference. Your carbs need to be tuned properly to get decent fuel consumption.

I use stock jetting (stock air boxes, stock exhaust). I live at 3400 feet ASL and have taken trips up to 7200 feet ASL. Works just fine.

If you have pods and open exhausts then re-jetting is likely required.

 

[5twins]

Yes, try the 7s. The BP7ES is available now at most auto parts stores for about $2. They come in boxes of 4, get one - 2 to use and 2 spares to keep on the shelf. Don't buy them at a motorcycle shop, you'll pay nearly twice as much for the same plug.

 

[swbill]

Wish I could get millage. With my wiseguys 2-1 intake and 36mm carb in lucky to get 30 miles.

 

[5twins]

You're probably jetted too rich. What really kills mileage is having the needle/needle jet too rich. The wrong mains and pilots can hurt too but that midrange setting is the biggie. That's where you spend most of your time running.

 

[Punkskalar]

My Black and White bike gets about 47-50ish, beating on it constantly....

 

[azman857]

55-57 mpg 2500 alt, city and county roads.