Fuel Range / Economy

[Keef]

Hi all
worked out that I'm getting about 22kms/litre.
Seem reasonable ?

I have a 16litre tank , 4.2 of it is reserve , so I should get about 250kms out of it before I hit reserve then the reserve should give me at least another 80kms , so my range should be about 330kms , maybe up to 350km if on road.

Does that sound about right ?
How does thta compare with your Dommi ?

[squirrelciv]

Getting around 19 km/ltr here. Tank will take 14 ltrs after just hitting reserve and that will do me about 275kms

[2001henry]

Congratulations! my 88 domie just has a 13l tank (probably 11 before reserve), and I can hardly ride it more than 200km (95% in town though) which is a mere 15.5 per liter...
and by the way, what can be done to make it less thirsty?
Henry

[samwise]

Congratulations! my 88 domie just has a 13l tank (probably 11 before reserve), and I can hardly ride it more than 200km (95% in town though) which is a mere 15.5 per liter...
and by the way, what can be done to make it less thirsty?
Henry

Ride more out of town

I used to hit reserve on my '88 at 170km, so that's the same as yours per litre (based on 13.5-litre tank with 2.5-litre reserve included).

Maximum I got out of a tank was 229km, but only put 12 litres back in the tank, so that was 19km per litre, mixture of minor roads and motorway, with some town work thrown in.

[Rubberchicken]

You could try replacing the needle jet, as these do wear over time creating a richer midrange and thus more fuel consumption.

I replaced mine a while ago, also fitted a platinum spark plug, and fuel use went from 17 km per liter to 19 km per liter.

[2001henry]

You could try replacing the needle jet, as these do wear over time creating a richer midrange and thus more fuel consumption.

I replaced mine a while ago, also fitted a platinum spark plug, and fuel use went from 17 km per liter to 19 km per liter.

Shall I replace it with OEM needle?
I've read somewhere that you need a different needle if you want to ride in altitude. What is it exactly that needs doing in this case? And where to find the needle? I'm planning to ride mine to the Pyrénées, so it might well be worth the change.

[Rubberchicken]

I meant the needle jet: The tube that the needle slides through.

These fellas:


Because the needle is usually hanging downwind it rubs against the same spot all the time, making the hole egg shaped, and letting through more petrol.



It's hard to see, but one of them is clearly egg shaped and the other one is brand new.

For riding in the mountains you might need a slightly smaller main jet because the air up there is thinner which would make the bike run more rich. But since most bikes these days are running a bit lean anyway I doubt you'll really need it...

[2001henry]

thanks rubberchkn, the pics + explanation are great, i think I'll probably do with changing the needle jet.

[Mervinh]

you guys do not understand carbs properly i recently found this tech article on the RD forum this will explain it all


Vacuum, venturi, bernoili's principle, hah! Here's what actually goes on.

Inside the carb are thousands of tiny gnomes, each with a small bucket. As you open the throttle, more of these gnomes are allowed out of their house and into the float bowl, where they fill the buckets and climb up the carb's passages to the intake, where they empty their buckets into the airstream.

But if you don't ride the bike for a while, bad things can happen. Tiny bats take up residence in the chambers of the carb, and before long the passages are plugged up with guano. This creates a gnome traffic jam, and so not enough bucketfuls of fuel can get to the engine. If it gets bad enough, the gnomes give up and go take a nap. The engine won't run at all at this point. Sometimes you'll have a single dedicated gnome still on the job, which is why the bike will occasionally fire as the gnome tosses his lone bucketload down the intake.

There has been some research into using tiny dwarves in modern carbs. The advantage is that unlike gnomes, dwarves are miners and can reopen a clogged passage. Unfortunately, dwarves have a natural fear of earthquakes, as any miner should. In recent tests, the engine vibrations caused the dwarves to evacuate the Harley Davidson test vehicle and make a beeline for the nearest BMW dealership. Sadly, BMW's are fuel injected and so the poor dwarves met an unfortunate end in the rollers of a Bosch fuel pump.

Other carb problems can occur. If the level of fuel in the float bowl rises too high, it will wipe out the Section 8 gnome housing in the lower parts of the carb. The more affluent gnomes build their homes in the diaphragm chamber, and so are unaffected. This is why the bike is said to be running 'rich'.

If the fuel level drops, then the gnomes have to walk farther to get a bucketful of fuel. This means less fuel gets to the engine. Because the gnomes get quite a workout from this additional distance, this condition is known as running 'lean'.

The use of the device known only as the 'choke' has finally been banned by PETG (People for the Ethical Treatment of Gnomes) and replaced by a new carb circuit that simply allows more gnomes to carry fuel at once when the engine needs to start or warm up. In the interests of decorum, I prefer not to explain how the 'choke' operated. You'd rather not know.
__________________________________________________ _____________


Now it would appear to me that the little guys are full of the joys of spring and working too hard, maybe a few words in thecarb teling em to slow down would help your fuel consumption

[Rubberchicken]

maybe a few words in thecarb teling em to slow down

NOOOOOOOOOOOOOOOOOOOOO