28 mpg

[TomB]

Agreed, as per my previous post. I just don't see how anyone gets 35mpg+ on one UK gallon, let alone a US one. I've had four XS1100's (running ones, that is) and even my new one didn't get that...

I can get 50mpg (ImpGal) out two of my XS's James, witnessed by other UK club members, other members in our club get 50mpg as well so I'm not on my own. Those two XS's have newish/low mileage carbs, one of them wears FJ1200 carbs the other XJ1100 carbs

My original XS did 50mpg when new blasting down the UK motorways at 100mph (though it did have a well streamlined fairing fitted at the time) that original bike now with 82K miles on the carbs only does 35mpg.

[TomB]

Mentioned here are the needle jets (emulsion tubes), I agree, the needles themselves could be well worn on high-ish mileage carbs which will significantly increase fuel use in the midrange.

Even with new jets, float heights set correctly, new mixture screws and set correctly the fuel use will be very high with worn needle jets and needles.

One other thing is checking plug colour, if you take them out after a ride when you're home all you've checked is tickover mixture ......coz thats the last thing the engine did before you turned off the ignition. You need to do different throttle opening plug chops, as in ...cut the ignition, snap shut the throttle and pull in the clutch to coast to a standstill all at the SAME time and check plug colour (with heat proof gloves), do this at different throttle openings to find out WHERE your carbs are rich. Sorry if this is teaching granny to suck eggs but you'd be surprised how many folk check how their bikes' running AFTER a ride




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[Yard Dogg]

THAT'S RIGHT BABY I LOVE CHOP TESTING!! GEAR GRINDING BALLZ IN THE WIND GRIMACE FACE WHITE KNUCKLE ROARING SCREAMING NASTY HOT DIRTY SPEED, then hit the kill switch and coast to a stop.

[TomB]

I'll have a pint of what Dawgs on please





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[BA80]

I can get 50mpg (ImpGal) out two of my XS's James, witnessed by other UK club members, other members in our club get 50mpg as well so I'm not on my own. Those two XS's have newish/low mileage carbs, one of them wears FJ1200 carbs the other XJ1100 carbs

My original XS did 50mpg when new blasting down the UK motorways at 100mph (though it did have a well streamlined fairing fitted at the time) that original bike now with 82K miles on the carbs only does 35mpg.

I'm not sure I can quite swallow that.

[fredintoon]

- - - No advance, your vacuum diaphram is bad or the hose is leaking. Not enough, probably the same issue. Either way, this will hurt fuel economy under 'cruise' conditions. - - -

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Hi Steve,
OK, I pulled the vacuum pot and did the poor man's check by sucking on it.
Little bastard whacks in and out just fine when I do that.
Tried moving the backplate by hand, kinda squeaky and sticks a bit so I squirted oil at it and now it moves nice.
Reassembled, started up and nothing moves.
Will check further tomorrow, gotta put the cover back on to go somewhere and the rig is my only transport.
BTW, the engine turns clockwise as you look at it from the left side and the vacuum advancer would turn the backplate counterclockwise if the effin' thing worked which means the bike is running retarded all the time?

[Yard Dogg]

Maybe the vacuum nipple is plugged on the carb intake boot. Sounds like it should work. How much pressure does it take to advance the timing?

[jetmechmarty]

I'm not sure I can quite swallow that.

Imperial gallons are big.

[James England]

Imperial gallons are big.

US gallon = 3.785 litres Imperial gallon = 4.54 litres

It's quite a difference.

[jwhughes3]

In England always drink pints, never shots....their ounces are smaller than US but their pints are bigger

John

[James England]

I can get 50mpg (ImpGal) out two of my XS's James, witnessed by other UK club members, other members in our club get 50mpg as well so I'm not on my own. Those two XS's have newish/low mileage carbs, one of them wears FJ1200 carbs the other XJ1100 carbs

My original XS did 50mpg when new blasting down the UK motorways at 100mph (though it did have a well streamlined fairing fitted at the time) that original bike now with 82K miles on the carbs only does 35mpg.

I bet if you put OEM carbs back on those two with the FJ and XJ carbs, you'd get a lot less than 50mpg.

Quite honestly, I find it pretty incredible that an XS1100 with a fairing gets 50mpg at 100mph. Really. I mean, how did you calculate that figure? Did you actually do 100mph starting with a full tank, then do a decent measured mileage (ie at least 25 miles) all at 100mph and then re-fill the tank?

One of my XS1100's was a Martini with an excellent OEM fairing. I toured most of Europe on that bike, all at legal speeds, nowhere near 100mph, and no way did it do 50mpg at any speed.

[jetmechmarty]

The fact is, I should be doing better than 28 mpg. Agreed? I'm finding it very difficult to get more than 30 mpg.

[DGXSER]

Agreed.

[jetmechmarty]

It may be fixed.

I put a vacuum gauge on the advance unit. It moves and it does not leak. I put the vacuum line back on the #2 carburetor. I started the bike, and nothing. The vacuum advance unit does not move when I open the throttle. I sprayed some solvent into the carburetor fitting and poked around with a piece of stainless steel wire. I cranked her up and now the advance unit moves when I crack the throttle.

Why would that orifice be plugged? It seemed to be running very strong, so I guess now it will pull harder. Thanks for all the help guys!

[TomB]

I bet if you put OEM carbs back on those two with the FJ and XJ carbs, you'd get a lot less than 50mpg.

The XJ11 carbs are MKIII BS34 Mikunis, with almost identical carb settings to the European 5K7 Sport only one size up on main jets which should make them richer, so changing them for original 5K7 carbs wouldn't make any difference.

FJ12 carbs are MKIII BS36 Mikunis with 142 mains in, they've been plug chopped carefully and the engine runs crisp but not weak. I have done 240 miles without going onto reserve with this XS (Avatar bike)

My original XS doing 50mpg was and still is on its OEM BS34 Mikunis, it did 50mpg over long distance touring checked through lots of tank fulls, its carbs are now well worn and does 35mpg

Sorry it sounds like bragging, I'm simply trying to say good MPG is possible without riding slow.

Here is Lamrics take on it Clicky


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