Hi all,

I just did a search on the average gas mileage and saw it was around 40-50 mpg.

I am getting roughly 70-80 MILES PER FULL TANK!!!!!  (thats before I switch to reserve - approx 11 litres)

What is going on,  please help with hints on what can be done to solve this. The bike is stock and I have just cleaned the carbs, checked the float height according to Mr Haynes and it appeared correct, although I'm not sure if I checked it correctly. 

Surely this mileage cannot be even close to normal.

Thanks everyone.

Sheesh!

No fuel leak?
Dirty Clogged Air Filter?
Carbs maybe stuffed? Does your exhaust pump out heaps of smoke (indicating you're running super rich?)
Dead cylinder?
Exhaust Blocked?
Valves stuffed?
Lack of cylinder compression


I can get about 350km's before switching to reserve.

Year and how many k's on the bike?

It's a 1990, can't remember the speedo mileage, 21000 something I think...

I cleaned the carbs 3 days ago, didn't really see any improvement with response, performance, fuel efficiency (or lack there of) and the bike still will not idle for love nor money.

I tried all differnet positions with the pilot screws with no noticeable difference.

No fuel leak, exhaust seems fine, the air filter is a tad dirty so I'll swap that out (can't see that as the only cause) and i'm fairly sure that she's running on both cylinders, although I couldn't say that I am 100% certain (I've never really attempted to confirm).

Other than the abysmal gas mileage and none existant idle, she seems to perform well enough, accelerates as one would expect, top speed around 105 -110 mph (indicated).

I have a similar issue with my old '81 Yamaha, I get 90/100 per tank and should get double that. A local bike mechanic has advised me to drill a couple of 3/8 holes in the airboxes, the filters are clean. He recons this is fairly common with "older" bikes. On no account run without filters.

On the grounds that it can do no harm, i can always tape over the holes, I have done this but I have yet to seen how the mileage works out. I trust the guy, he is something of a guru for bikes from the 1930s and 40s

Maybe looking at the spark plugs will give you some clues. Most likely a previous owner screwed around with the carbs, which you should never do. A stuck or dirty float valve might cause excess fuel supply but a dirty plug would result.

Quote from: ballyhoo on May 31, 2006, 11:55:13 AM
Most likely a previous owner screwed around with the carbs, which you should never do.

Yes!  Never!  They are perfect straight from the factory and they will stay perfect!   

Tire pressure maybe?  Although I doubt it would make THAT big a difference.

Also if you're normally doing 110 mph your fuel efficiency will be lower.  I get about 55-60 mpg but normally stay below 65mph.

I regularly ride in the higher RPM range and still rarely ever switch to reserve before 180 miles.

My huge ass Monte Carlo gets better gas mileage than your GS. There's something really wrong with that.

Dave

Quote from: My Name Is Dave on May 31, 2006, 12:41:47 PM
I regularly ride in the higher RPM range and still rarely ever switch to reserve before 180 miles.

My huge ass Monte Carlo gets better gas mileage than your GS. There's something really wrong with that.

Dave

Hmm, I fill up after 100 or so miles and always seem to put about 3 gallons in when I'm just driving to work and back (I ussally ride aggressively in the city though) two gallons when going on trips.  What the hell, do I have another problem I didn't even know about?

Quote from: NWDave on May 31, 2006, 03:07:44 PM
Hmm, I fill up after 100 or so miles and always seem to put about 3 gallons in when I'm just driving to work and back (I ussally ride aggressively in the city though) two gallons when going on trips.  What the hell, do I have another problem I didn't even know about?

I get 180-200 miles regularly before having to switch to reserve, and I also use my GS for commuting although it's usually on the expressway.  You might wanna look into that though... 

Quote from: NWDave on May 31, 2006, 03:07:44 PM

Quote from: My Name Is Dave on May 31, 2006, 12:41:47 PM
I regularly ride in the higher RPM range and still rarely ever switch to reserve before 180 miles.

My huge ass Monte Carlo gets better gas mileage than your GS. There's something really wrong with that.

Dave

Hmm, I fill up after 100 or so miles and always seem to put about 3 gallons in when I'm just driving to work and back (I ussally ride aggressively in the city though) two gallons when going on trips.  What the hell, do I have another problem I didn't even know about?

Yeah, that's low.

tires pressure
worn plugs/wires
chain out of adjustment (this would be very clear)
worn bearing (wheel)
brakes dragging
carbs need to be rebuilt and tuned properly
exhaust blockage my seem to flow right but has restriction in it.

Maybe you are only filling till it auto-stops? I think I can get in 1-2 galls till it auto-shuts off. After that I can put in another 2.

Quote from: NightRyder on May 31, 2006, 05:41:48 PM
Maybe you are only filling till it auto-stops? I think I can get in 1-2 galls till it auto-shuts off. After that I can put in another 2.

ummm, no.

Gonna be getting my carbs back soon, had them cleaned and rebuilt by a friend.. but  ya more than not, if I'm just riding to work and back it seems I have to switch over to the reserve at around 100 miles.

Quote from: galahs on May 31, 2006, 03:49:39 AM
Sheesh!

No fuel leak?
Dirty Clogged Air Filter?
Carbs maybe stuffed? Does your exhaust pump out heaps of smoke (indicating you're running super rich?)
Dead cylinder?
Exhaust Blocked?
Valves stuffed?
Lack of cylinder compression


I can get about 350km's before switching to reserve.

350km? How the hell? I can hit 225km on around 8 liters of gas. Dont know if that's normal as I have no clue what a gallon is, so can't match my mileage towards the numbers that's given here.

52.000km on the clock and 93 model.

Anyone who can tell me if that's good or bad?

140 miles to 2.1 gal = 66.6 mpg evey evey good

Quote from: shik on May 31, 2006, 06:38:20 PM

Quote from: galahs on May 31, 2006, 03:49:39 AM
Sheesh!

No fuel leak?
Dirty Clogged Air Filter?
Carbs maybe stuffed? Does your exhaust pump out heaps of smoke (indicating you're running super rich?)
Dead cylinder?
Exhaust Blocked?
Valves stuffed?
Lack of cylinder compression


I can get about 350km's before switching to reserve.

350km? How the hell? I can hit 225km on around 8 liters of gas. Dont know if that's normal as I have no clue what a gallon is, so can't match my mileage towards the numbers that's given here.

52.000km on the clock and 93 model.

Anyone who can tell me if that's good or bad?

Mine is a 2005 GS500F.  I have a 16 litre main, and a 4 litre reserve.

That's only 4.5 litres for 100km's.

With conservative riding I can get it to very low 3's.

OK, so I went over the entire bike last night....

-Brakes aren't dragging,
-tyre pressures are good,
-wheel bearings are good,
-chain is fine (cleaned, oiled well adjusted).
-I pulled the plugs and they are covered in soot so I'm obviously running rich. (the plugs are relatively new)

So I tried running on the left side (gear lever side) on its own and it ran ok, then swapped to the right (brake lever side) and it ran but was richer than the left but still ran.

One point is the fact that I screwed the pilot screws all the way in so they are closed (not letting any fuel through) and this helped with the idle and running on each cylinder but only slightly.

So I'm guessing my problem is I'm running really rich, I suppose I'll have to take the carbs off again. Anyone know the best, most accurate way of measuring the float heights, and anything esle you can think off would be appreciated.

Thanks everyone.

P.S. my friend, the person who owned the bike previously does tinker with things alot and almost all the time they don't work afterwards so god only knows what he may have altered.