Darmah fuel consumption

[hashashan]

Hey guys,
I noticed that i can pour fuel out of a bottle at the speed that my darmah drinks it and i wondered is 1:10 ratio(liter per 10km) is normal.
how much fuel your darmah's drink?

[sevicke]

mine drinks a bit but i dont care well worth it not concerned with economy
not riding in an economicqal way either taps open all good. costs more to run than my ute by a long shot

[abmartin]

My SS with 40 mm carbs uses about 5 litres per 100 km which seems to be about normal for these bikes.

Bruce

[Craig in France]

<snip> ... and i wondered is 1:10 ratio(liter per 10km) is normal.

No, Hashashan, that's way off.

The owner's handbook claims 5.5 litres/100km = 18 kms/litre (see "Performances" on page 42). While that may be a bit optimistic, I personally never get less than 45mpg = 16kms per litre (SSD, 32mm carbs).

What size carbs are you running, and what jets?

Ciao

Craig

[mgh1955]

Consumption will vary with depending on city/open road and sedate / agressive. None the less, a well maintained/tuned sd900 engine should run reasonably economical on open roads and steady medium speeds (say around 110kph). I get about 16.5k's per litre (say 6 litres per 100k). Anything significantly less than that indicates a problem.

So if you are only getting 10k per litre at steady open road speeds then yes something not quite right. Check plugs and see if they are heavily 'oiled' (running rich).

Could be a variety of causes - clogged air filters, incorrect carb settings, poor ignition, poor compression, overweight pillion passenger!!

Mick

[garryc]

Both an Aussie mate and I have 78 SD's and neither of us can get much more that 150 ks out of a tank.

[hashashan]

well the plugs do get black but nothing I could do could fix the problem. I guess the carbies just had better days and should be replaced soon.
I use 32mm carbs with 122jets(thats what is written on them). open air filters(yes they are clean)
what does the iignition has to do with it? and how can I check it ... my ignition is the original system so that could be a problem

[mgh1955]

Hashashan

I run 40mm dellortos with K&N filters so I don't know if you have right main jet for 32mm units.

If the ignition timing is 'late' (plugs spark latter in compression stroke than they ideally should) then air/fuel mix is not fully combusted in time to generate maximum expansive force on the piston crown as the piston is already well advanced on its down stroke (we are talking milliseconds here)

The other ignition problem is the spark has less 'ooomph' than it should and again result is less than efficient combustion with reduced force on piston crown. Try new plugs for a quick and not too expensive diagnostic check for this one

Aside from that if ignition is problem and I am not saying it is, you need to get an expert to do the diagnostics (coils status, timing check, etc)
If your bike has bosch electrics though as I have had no trouble with mine I'd suspect carby problems first.

If slide needle is old it may be worn such that carby is sucking in more fuel than can be efficiently 'used' in the combustion process.
Pull out slide and have a close look at the needle. Is it pitted &/or ridged?

There is no need to replace carbies (if bodies are OK) as they can be overhauled. Buy yourself a dellorto 'overhaul' kit and new needles if existing are worn.
Plenty of info (diagrams etc) on this site.

Probably worth doing a compression test on cylinders as well
This link has info
http://www.docv.org/cgi-bin/news/newssc ... plate=site

Mick[/url]

[Craig in France]

Both an Aussie mate and I have 78 SD's and neither of us can get much more that 150 ks out of a tank.

Scary, Garry . You should be getting 240+ (the factory claimed 270km per tank).

Ciao

Craig

[Craig in France]

Hi Hashashan,

122 is the specified jet for use with the factory air boxes. So, if you're running open filters, you're on the small size, if anything. So, next questions:

1. What size idle jets do you have? They should be 55 or 60 depending on which type of 32 carbs you have: 55, if PHF32C; 60, if PHF32A

2. What size needle? Should be K16 (or K6), with the clip in the middle.

3. The slides should be 60/3 for PHF32C; 70/2 for PHF32A.

4. What condition are the needles, jets and slides in? If the bike has been running without proper air filters, both the needle and the slide - and the carb body itself - can be extensively damaged.

5. Are the pumps working?

6. As Mick said, what are your compression readings? Have you checked the valve clearances?

7. What's the fastest the bike will go? Should be around 180-190 km/hr.

Ciao

Craig

[hashashan]

I dont have any idea what type is my needle or the udle jet .. where can I see it? The clip is not in the middle but ratehr all the way up. I have this problem with my bike that it constantly kills spark plugs, it will take him about 30 inutes to cover the plug with black soot. So I moved the needle as low as possible to lean the mixture, well it didnt help.
The needle is in rather normal condition, no visible scraches or pits, however it is not new and possibly should be replaced.

4) how can i know the condition of the jets? or the slides???, it has proper air filters, K&N.
5)what pumps? the jetting pumpos on the side... you mean when i press them do they spit in fuel .. if this is what you mean then yes.
6)didnt do a compression test yet. and didnt check the valves, which could also have a problem with their rings I have a suspicion that I have oil in the cylinders.
7) 190?????? when I got it went 160 and I didnt push it further because it wasnew to me and I was afraid now it goes slower, much slower. I guess i can get it to run 160 but 190 .. no chance.

I want to get new carbs because I wanted to upgrade them to 40mm. anyone selling?

now regarding the sparks, I guess I have a poor spark because the spark plugs are always sooted ... anyone has any ideas why is that? oil? bad carbs?
I do have bosh electrics but I still want to change those. they are very old and probably faulty.
about the ignition timing.... any chance I can check this w/o a stroboscope?

[Craig in France]

Blimey Hashashan, you aren't half making us work hard ... . Right, here goes:

I dont have any idea what type is my needle or the idle jet .. where can I see it?

Both parts have the numbers stamped on them, as do the slides. You may need a magnifying glass to see the numbers on the needles.

The clip is not in the middle but rather all the way up. I have this problem with my bike that it constantly kills spark plugs, it will take him about 30 minutes to cover the plug with black soot. So I moved the needle as low as possible to lean the mixture, well it didnt help.

Not surprised. Your problem is not with the main jet.

P.s Do you KNOW that the enricher (choke) pistons are sealing properly? These MUST seat properly. If not, you are running with them on all the time . And this may be all of your problem .

Best thing is to simply buy and fit new ones. Steve Allen has them @ $8.50 each. Also, make sure you have some free play in the cables.

how can I know the condition of the jets? Or the slides???,

Visual inspection is all that is necessary. Look for scratches or areas of wear - these will show up as shiny.

... it has proper air filters, K&N.

(Not my idea of proper filters, but each to their own.)

... what pumps? the jetting pumps on the side... you mean when i press them do they spit in fuel .. if this is what you mean then yes.

Good. Part of their purpose is to enable you to run a smaller idle jet.

... didnt do a compression test yet. and didnt check the valves, which could also have a problem with their rings I have a suspicion that I have oil in the cylinders.

Which could be a consequence of the engine running too rich. The excess petrol can wash the oil of the bores and lead to ring failure. You need to do that compression test ...

... now it goes slower, much slower. I guess I can get it to run 160 but 190 .. no chance.

Again - you need to do that compression test.

I want to get new carbs because I wanted to upgrade them to 40mm. anyone selling?

Try Steve Allen. But be aware that it's not a straight forward swop. You will also need to get different inlet manifolds and, possibly, new cables. Steve will advise.

...now regarding the sparks, I guess I have a poor spark because the spark plugs are always sooted ... anyone has any ideas why is that? oil? bad carbs?

Your plugs are fouling and failing because your bike is running WAY too rich!!

...I do have bosh electrics but I still want to change those. they are very old and probably faulty.

One thing at a time, Hashashan! Get the carbs working right first! Why do you want to change the ignition system? Unless you intend tuning the bike for racing, the Bosch system is fine ...

...about the ignition timing.... any chance I can check this w/o a stroboscope?

Yes.

Ciao

Craig, exhausted

[hashashan]

first of all, thanks for all the help.
does anyone of you ever used the colortune plug to check the mixutre, well i have. and the mixture seems fine, at least it gives the perfect color.
oh and about the choke, i am nearly 100% sure that the problem is not with the choke. the o-rings seem fine and the channel is clear. also I fitted the cables all the way to the bottom.

[Craig in France]

first of all, thanks for all the help.

No worries!

does anyone of you ever used the colortune plug to check the mixture, well i have. and the mixture seems fine, at least it gives the perfect color.

I used to use one years ago, but only as a rough guide. However, the fact that you've got a blue flame is interesting ... How many turns out are your mixture screws?

oh and about the choke, i am nearly 100% sure that the problem is not with the choke. the o-rings seem fine and the channel is clear. also I fitted the cables all the way to the bottom.

Sounds good, especially if the ColorTune is telling you the idle setting is good/near enuf. However, be aware that the seals at the bottom of the pistons can look ok, but still not be sealing well. Are they hard? Can you see the marks of the enricher jets on them?

And there is (yet another!) possibilty ...

If the floats are set too high, the bike will run rich. Personally, I don't find float heights the easiest thing to measure, but the procedure is described in the Dell'Orto manual here
http://www.filejumbo.com/Download/2AF768C516D326F8

And here's another way that someone else uses:

To check the float height without removing the carb from the engine:
• Using a piece of alloy strip, make a tool which spans the carb body and has an depressed central section that will allow the floats to drop by 17mm.
• Close the fuel taps
• Remove the float bowl of ONE carb
• Hold the float up with the tool
• Open the fuel tap. If fuel flows, close the tap and bend the tang UP and check again
• If no fuel flows, gently move tool down so that the float down falls until petrol flows. If you need to move it more than 1mm (which would make 18mm total), you need to bend the tang DOWN.

Ciao

Craig

[hashashan]

what do you mean how many turns out my mixture screws? I just didnt understand you.

ummm what selas, what pistons? the engine pistons? once again I dont get you (I guess I have the problem here )

and the floats are ok, my mechanic told me so, I guess that his opinion is good enough for me, or at least I wont be able to measure it better then him.