High fuel consumption

fj12_rider · February 25, 2013, 06:12:15 AM

Hey all .
I`m having problems with really high fuel consumption . Can anyone give me some Ideas to check ? I was getting up near 200 mile per tank and i`m currently getting around 130 . Theres no leak that I can see or smell . I`ve had the carbs off for a clean and set them up (not synced them as yet as i have no guage) its a 1990 and the pilot screws were open at almost 4 turns out . I`ve put them back to stock at 2 turns out , theres a bit of a flat spot now at 60 ish mph but i`ll open them up a little but more to get rid of that . Any help will be most appreciated , its costing me a fortune at the min !

Cheers
Dave

fj11.5 · February 25, 2013, 06:21:56 AM

its possible that the o,rings on the needle seats under the floats are perished and letting fuel past, next time you have the carbs off, with the float bowls off, leave the carbs upside down and blow into the fuel inlet tube, if its the o,rings not sealing you should be able to hear air

fj12_rider · February 25, 2013, 06:33:36 AM

Thanks for that , The other thing I neglected to do was check the float height thinking about it . I`ll get them off this avo and check them .

Cheers , anything else I can check ?

fj11.5 · February 25, 2013, 06:51:49 AM

cant think of anything else at this late hour

but will post up if i do,, float heights being spot on make a big difference to consumption and running better, ,

FJmonkey · February 25, 2013, 07:09:20 AM

I use to get 50mpg, then I put UNI pods and a Suppertrapp on, more like 43/45mpg. Remember to turn the choke off, that will kill your mileage.

fj12_rider · February 25, 2013, 10:47:37 AM

Cheers monkey; I always kill the choke within prolly 30 secs . She doesnt like to run too long on it anyway .

I pulled the carbs off again today and they were covered in all manner of gunk .

These are the 2 I haven`t worked on yet :

These are the 2 i`ve finished I sprayed the tops black:

I`m sure they were working at they`re best looking like that especially the chokes , I`ll do the other 2 tomorrow and see what happens .

The floats in the 2 i`ve worked on were 2mm out on the float height ! both were around 20mm and should be 22.3mm

Pat Conlon · February 25, 2013, 10:51:11 AM

How do your plugs look?

fj12_rider · February 25, 2013, 11:16:06 AM

Quote from: Pat Conlon on February 25, 2013, 10:51:11 AM
How do your plugs look?

They look ok , little bit sooty maybe but nothing too bad . They are prolly pretty old

Pat Conlon · February 25, 2013, 11:33:00 AM

They look a bit rich but not too bad. On the factory carb settings, my plugs were white.
Set your floats then get your carbs sync'ed. The proper sync. makes a big difference.
Run a couple of tanks thru, and see where you're at.... Let us know how you are doing.

fj12_rider · February 25, 2013, 12:00:58 PM

Will do thanks mate.

I made a manometer last year but it wasn`t that great because I didnt have anything to reduce the airflow enough to get a settled reading . I`ve ordered some tap valves now so I should be able to get them sync`d up in the next few days . Will be interesting to see how far out they are as they have definately been "fiddled" with .

racerrad8 · February 25, 2013, 03:20:53 PM

Quote from: fj12_rider on February 25, 2013, 10:47:37 AM

I see the spring for the sync adjuster is not in the proper position on this set of carbs. It is trapped around the flange where it should just be under the flange applying linkage/sync pressure to the screw.

Randy - RPM

andyb · February 25, 2013, 03:41:24 PM

Quote from: Pat Conlon on February 25, 2013, 11:33:00 AM
They look a bit rich but not too bad. On the factory carb settings, my plugs were white.
Set your floats then get your carbs sync'ed. The proper sync. makes a big difference.
Run a couple of tanks thru, and see where you're at.... Let us know how you are doing.

+1

When things are right, they're whiter than many people would expect, but that assumes you ran the bike long enough for them to burn clean after using the choke to start it.

andyb · February 25, 2013, 03:45:32 PM

Quote from: fj12_rider on February 25, 2013, 10:47:37 AM
Cheers monkey; I always kill the choke within prolly 30 secs . She doesnt like to run too long on it anyway .

Betcha things are richer than they need to be then, unless you live in some strange portion of the UK that I'm unfamiliar with. Takes a bit of time to get things warm enough to have decent throttle response without the choke... hopefully not >15min, like the wife's VF was on stock settings (since fixed, obv), but a few minutes of riding at least. Unless you're saying it idles okay without the choke but still has some fluffiness in the throttle.

(Sorry about posting twice, trying a different format to read things in.)

fj12_rider · February 25, 2013, 04:49:24 PM

Quote from: racerrad8 on February 25, 2013, 03:20:53 PM
Quote from: fj12_rider on February 25, 2013, 10:47:37 AM

I see the spring for the sync adjuster is not in the proper position on this set of carbs. It is trapped around the flange where it should just be under the flange applying linkage/sync pressure to the screw.

Randy - RPM

They aren't put together just pushed them together for the photo :-)

Andy : the last time it was run was litterally a couple secs to get it out of the shed on choke so its a bad example really , I'll show again when I've run it for a bit

fj12_rider · February 28, 2013, 10:26:10 AM

So .... Carbs cleaned and adjusted , Refitted . Valve clearances adjusted had to change the shims in 6 , will sync the carbs up tomorrow and then run a couple of tanks of fuel through it and see what she give me. It SHOULD now be the best I`m going to get from it anyway so there isn`t a lot else I can do , so fingers crossed she`ll be all good now . The throttle response is way way better thanks to the new shims anyway .

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High fuel consumption