'99 KTM exc 300- mental fuel consumption!

[multijoy]

I've posted about this bike before (bit of a hard starting issue), which may or may not be linked.

Anyway, today we did the bocketts run as far as we could before the 300 ran out of fuel. Fine, no problem. Off to petrol station, fuel can, back, time to head home.

Until it ran out of fuel again. Back of the fag packet sums suggest that it's doing somewhere in the region of 20mpg, which really doesn't seem right!

Temperamental start aside, the bike seems to be running fine. It's on premix, 50:1, give or take a whisker. Could probably do with a new spark plug, air filter cleaned and oiled yesterday.

Is 20mpg about right for a 300 2t, or is this a symptom of something else? It does also have a tendency to piss fuel out of the carbs when leant to a side (not enough to account for the current consumption!) which does suggest that there is something not quite right there (although I have been led to believe that this is an 'endearing' feature of these machines).

Any thoughts?

Cheers,
Rich
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'11 CBF1000A, '99 C90, '98 CB500
silky666: He rode amazingly well considering his bike is the weight of a small van and had slicks on.

[Wafer_Thin_Ham]

Stop pinning it everywhere?
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[Adamantis]

It doesn't get pinned everywhere - far from it! Pootled the nationals at about 45 in top gear, flipping the revs around so it doesn't sit in one place for too long.

Just before it runs out of fuel it makes a distinctive noise - I can only describe it as the bottom note vanishes, and it just makes the high "scream" noise?

Laura
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Rides: '91 CG125 (Sold), '00 CB500S (Sold), '97 Thundercat (Sold), '99 KTM EXC 300 (SOLD), '99 RSV Mille (stolen. Thieving SCUM!!!), '94 DR350 (sold), '10 Vstrom 650 (hated it so much I gave up riding), now on the OH's CBF1000 until I can afford another Mille...

[Frost]

Bigger cylinders tend to give worst economy, so i wouldn't expect greatness form a 300 2t! On the other hand though 20mpg is very shit. Apparently the bike has a 2.25 gallon tank, so you're getting 45 miles per tank? Gearing is an issue too with off road bikes as the gears tend to be very short and closely spaced. The hard starting could be related to it running rich and consuming more fuel as a result. An easy way to test this is to try starting it when hot, and first thing on a cold morning. If it starts as well or better in the cold it's running rich.

[.....]

45 miles from a tank isn't too bad. I think I get about 55 from my Gasser and I think the tanks are the same size.

No fuel coming from the carb overflow?

[multijoy]

Only when it's tipped to the left!

I wonder if the idle is upped a whisker it'll avoid having to keep the revs on when it isn't needed, which could make a bit of difference.

Good to know it's in the right ball park, though. It's only the 15 miles to/from the lanes you really notice it the low mileage. Might be worth a bigger, or at least transparent, tank!
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'11 CBF1000A, '99 C90, '98 CB500
silky666: He rode amazingly well considering his bike is the weight of a small van and had slicks on.

[boundy]

I was only getting about 25 on my GasGas ec300, having the carb correctly jetted, fresh spark plug and air filter should make a notciable differance

[stevo as b4]

I wouldn't expect much mpg from a big 300cc+ 2stroke engine IMO. My old KMX200 was used mainly on the road, and it would never do more than 40mpg at the most. I would think a 300 or bigger would be down to 25mpg easily really.

[G]

Definityely worth doing general maitenance and cleaning out the carb too, while you're at it (should be very easy to do). My 200 went from being a bit bitchy starting to very easy/regular!

There's plenty of options for a bit bigger tanks. The 4 strokes do do better on fuel, but then do worse on maitenance and make a horrible mess when it all goes wrong!

[stinkwheel]

My dads KH350 does about 25mpg. My old 350 powervalve could easily drop below 20mpg if ridden enthusiastically.

So, 25mpg from a performance 300cc 2-stroke engine isn't outwith the realms of possability.
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“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[multijoy]

Might be time to work out if a small van will be cheaper than the run from home to the lanes!

That or a tow rope...
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'11 CBF1000A, '99 C90, '98 CB500
silky666: He rode amazingly well considering his bike is the weight of a small van and had slicks on.

[garyd]

a small van would be even cheaper on the lanes
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CRF230 all you need

[Blue_SV650S]

My 250 does ~25mpg so, no, not surprised you are getting ~20mpg!

It is ridiculous and means you need to plan regular fill-ups/a route with petrol stations that are no more than 40(ish)miles apart!!
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The purpose of life is to fight maturity.