Why is my bike only getting ~41 MPG?

[Juan1]

My bike is an '89 that was purchased with about 5,000 miles on the clock, and my mechanic stated he believes the mileage.  It was apparently crashed, and them spent lots of time in storage.  Within the last 1,000 miles I've done the valves, taken care of a vacuum leak, cleaned and balanced the carbs, and the bike runs well.  A compression test shows it'll handle over 150 PSI on both sides, and the bike still can get up into triple digits.  Still, I'm getting relatively bad gas mileage despite the fact I'm not flogging it.  Anyone have any ideas on possible culprits?

[natedawg120]

what's the length of your average ride?
air filter clean?
got jets?

[Juan1]

Air filter is clean.  Jets are normal.  Average ride is 15-20 minutes.

[kml.krk]

if you're mostly riding around a city (strop and go traffic) your mileage is going to be highly reduced.
That is why car companies always advertise car's mileage as "Highway Mileage",because you get most miles to the gallon on the highway where you don't have to constantly accelerate or decelerate.

just my thoughts, please don't quote me on this one 

[fred]

Eh, that's about what I get on my '94 commuting to work every day. Fuely  I wouldn't worry about it too much. Worry if you start getting something very far from average without a significant change in riding style. Perhaps check your plugs to see if you're running super rich... You can look at my data for the last year here: http://www.fuelly.com/driver/fredzyda/gs500e-2

The guys who are reporting 60 or more miles to the gallon seem to all have F models with jetting on the lean side and only ride on super flat country roads with no traffic at 40 miles an hour. If you ride in traffic a lot in a hilly place or drive at freeway speeds a lot, you're going to get worse mileage.

[Juan1]

Fred,

Thanks for that info.  I do live in San Diego and have used the bike to commute.  Now that I'm done fixing mechanical stuff on the weekends, I can see what she'll do on longer rides.

[ohgood]

if you're mostly riding around a city (strop and go traffic) your mileage is going to be highly reduced.
That is why car companies always advertise car's mileage as "Highway Mileage",because you get most miles to the gallon on the highway where you don't have to constantly accelerate or decelerate.

just my thoughts, please don't quote me on this one 

sorry, had to quote

actually, the gs gets better milage (from my experience) commuting than on the interstate. provided you don't gun it from every green light or stop sign.

try it-

one afternoon tooling around town at 34-50 mph, NOT gunning it

vs

one afternoon riding interstate speeds 75-85 mph constant

you may be surprised.

F models may fair better, provided you 'tuck' a little.

[drewbytes]

My bike gets 52-54 US mpg (4.3-4.5L/100) whether I commute, ride on the highway, slow riding practice or whatever. It's almost always exactly the same mileage. I got that as stock and still get the same with exhaust, filters and jets.

I can't imagine getting 5.5L/100 (42 mpg) no matter how hard I rode it so it certainly points to something not being right.

[murf425]

Check your tire pressure.  My bike suddenly went from 60 mpg to 45, and I couldn't figure out why.  Turned out my rear tire had 12 psi in it!!  Problem with bike tires is that they're pretty rigid, so you can't look at it and tell it's low.
Filled it up and my mileage instantly went up to 55.  The rest I blame on the air filter, which I just haven't gotten around to replacing yet.  Spark plugs, too.


Of course, my new bike is going to be less than 45 on the best of days, so...

[natedawg120]

yeah 15 to 20 minutes isn't a long commute that is probably what is dinging you the most.  Check your tires and if that's all it gets mileage wise as long as it's running strong you might just have a thirsty GS. 

[The Buddha]

I got 45 with K&N and pipe with a 25K mile 89 on commuting type running.
If your exhaust isn't smelling like gas - even faintly, then check intakes and air box and what not for over flow.
Oh, I had an ignition advancer in mine, likely made a small difference with complete combustion.
Cool.
Buddha.

[ATLRIDER]

My 96' has a full V&H, lunchbox, 15T sprocket, ign. advance, 150/40 jets.  Getting around 40mpg running on at hwy speeds.  Changing the sprocket made a big difference in reducing mpg.

You running stock jets?

[ivany]

Fred,

Thanks for that info.  I do live in San Diego and have used the bike to commute.  Now that I'm done fixing mechanical stuff on the weekends, I can see what she'll do on longer rides.

Hey there, another San Diegan.

I live around here too. I commute to work and school (10-20 minutes per trip) and get very reliably 47 mpg. So you're not very far off. Almost 100% of my riding is city - when I took it out on the freeway for long trips my mileage shot up to mid 60s - even saw 74 once. So, don't worry about it!

[commuterdude]

mebbe a lil brake drag or too many cookies......

[lilwoody]

The guys who are reporting 60 or more miles to the gallon seem to all have F models with jetting on the lean side and only ride on super flat country roads with no traffic at 40 miles an hour. If you ride in traffic a lot in a hilly place or drive at freeway speeds a lot, you're going to get worse mileage.

I'm a guy getting 57 (was getting 60 until E10) riding with my wife on 260 mile round trips to Key West or really anywhere outside the city. It's pretty flat around here, except the bridges and we surely aren't doing 40 but I'm not driving like I stole it either. I'm going to Marathon solo tomorrow (160 miles round trip) I'll post the milage monyana. I notice around town I do get less milage but my bike rarely sees 9500. Keep it under 6k and you should get good milage.

[fred]

Here's a fun side note to this discussion: My GS had a leaky caliper, so for the week and a half it took me to get parts and fix it, I borrowed my friend's KLR250. I fixed my GS last night so when returning the KLR, I filled it up and checked the mileage. Riding that bike for a week and a half on the same commute as my GS I got 49.5 miles to the gallon. It seems like my particular combination of riding style and commute just doesn't lend itself to great mileage...

Another fun fact: after riding a KLR250 for a while and switching to the GS, the GS feels like a superbike! If you want to take a stock GS and make it feel like it is the fastest thing you've ever driven, just ride around on a 250 every day for a bit and switch over.

[bill14224]

You can read my bike's specs below.  I average about the same whether I'm commuting through the suburbs, which I do every day, or go on a 100-mile blast through the country at 70-80.  Every time I fill-up, I'm putting in about 3.5 gallons after 200-220 miles.  I am being as forthcoming as I can be.  Only one time did I actually "ride for gas mileage".  I went camping for a week and got 67 mpg on that tank, and that was before I got the 17-tooth front sprocket and the V&H pipes.

[Juan1]

mebbe a lil brake drag or too many cookies......

The bike is running great, compression is good, the valves are within spec and the plugs look ideal, so I don't think the engine is the issue.  The sprockets and chain are new and are adjusted properly, so I'm ruling that out.  I've been riding fairly conservatively, so I'm ruling out a lack of self control.  There are no fuel leaks, so that isn't the problem.  However, my front brake is dragging a tad.  I'll back it off tonight and check the rear brake while I'm at it.

[qwertydude]

Sprockets and chain might be new but did you count the teeth? Should have 16 in the front if it's got a 15 or 14 you'll definitely lose some mpg. Also what rpm are you actually shifting? For everyday riding I shift at 3500 to 4000, if I need to go faster I just open up the throttle more, lots of times full throttle, but still shift early and keep rpms low. With a 18 tooth front sprocket no matter what, I never see less than 60 mpg.

[The Buddha]

BTW Buddha jetting is not great for power or gasmileage. Its developed to be right for all weather riding, coldest rainiest day in the world and it will start and run, for quick starts and predictable warm up and no rpm hovering upon closing throttle, and general cool running.
Better power and mileage, lean it out some, maybe go to a smaller main or get needles out form the washers.
Cool.
Buddha.