Taffy

the list of people who like the Dell is very short but most of the problem stems from lack of help/results. I've heard little good said about them....shame.

But let's be fair, very few people have done much with them Heimar Bardasson and a couple more are all that come to mind.

even then the info was dumped but nothing really done to help people in the deep doo-doo.

Taffy

Taffy

I've intimated that I have learnt something about jetting, well certainly dell orto specific jetting very late on in this. I invite you to spot the mistake I have made all the way through before I learnt that lesson.

looking back, it can be seen that I was being told by the bike but ignoring it!

Thursday 25th April 2019. nice cool spring evening
start with the old jetting for a run.
185MJ, K58, C5, 45PJ, .75 turns out of the FS, DR276 atomiser, /65 slide cutaway, 1.5MAJ, 0.4PAJ.
test; pulled very well, didn't start so easily.

Special needle fitted on C5.
ran great, could catch it out now and again doing a snap wheelie test.

45 to 42PJ
crisper low revs and FS up to 1.0 turns.

C5 to C4.
great respons mid revs and able to take really low idle

Tue 14th May
new DCPR8EIX fitted.
little dry low down. secondary snap not there. C5 again maybe?

decide to plough on with reducing the slide cutaway so the PJ can also come down.
/65 to /50.
fuel screw immediately can turn to zero and still runs!
test;
blubbered and missed an intermittent beat at low revs (very rich)
the S in SNAP was great, the NAP was rich.

42 to 40PJ
DR276 to DR274
FS happy at 0 but left at 0.5 turns out. still burbling.

PJ40 straight past 38 to PJ35.
FS now happy at 1.0 turns.
Fantastic! Idle shot up! FS now dies between 0.5 and closed. (as it should) Really, this is the best ever!

was going to go home but push myself; 'go on, test something'.

so DR274 to DR272
starting is the best i can recall, i can't even hear the button, it is just running. only ever been like that once before in all the tests.
Curates egg though (so good in parts) it got richer at idle and goes dry in the pilot area.


well!
might as well see if someone can spot what i say things do in the first post and then spot what is happening several times but it hits me here on this day and I realise I have been making a mistake that has cost me many, many hours of testing....

Taffy

Taffy

see the diagram above.
the K51
what your seeing is the richness of the original needle. it is lean on the needle straight which can be seen against the left wall of the chart. it starts way leaner (and below) the K58 and then goes mega rich.

I've tried to show the K58 'special'. note I've added a purple line which roughly represents what I've done by hand to the needle. I've made the taper start around 5mm earlier and then blend in. But it isn't the 8mm difference in start of a K51 (44mm FtT) and a K58 (36mm from the tip). I'm putting it on a shadowgraph to see WHEN the taper starts and then I'll draw it up.

If you look in previous charts you can see that one clip difference wrecks the bike and is but 1mm visually in the charts but look at the void between the K51 and the K58!!! it's like the middle of the K51 and the K58 are different by around 40 clip positions! every single needle drop has had an effect on another part yet there are 40 needle slips of difference.

the next thing to notice is that some of you will know that the Keihin "Superneedle" i do has 4 angles of taper.

well count the angles in the K58 special. Three! but the point is, a 650 Husaberg is a 650 Husaberg whether it is 2001-2003 or 2004-2008 and they both want the same fuel curve. same goes for the 550 and the 501.

the same needle that I put in a keihin carb for the 380 husaberg i put in the 650 and the only difference is one PJ and one MJ difference.

it therefore stands to reason that this needle when done is, with small changes going to work for all Husabergs 350-650. all I need to do is tickle up the knowledge on each CC and country etc.

cheers

Taffy

Taffy

Ok to bring us up to date

Wed 15th May
MJ; 185
MAJ; 1.5
Needle K58 special
Clip; 4
PJ; 35
Slide: /50
FS; 1.5 turns

first ride of the day and excellent except a little dry spot at 2mm of opening.

needle C4 to C5 - see if I can't get rid of it.
test; now has a double stutter, worse!

C5 to C3 and FS happy ay 1 turn out but will stall if all-the-way-in (as it should)
test;
no report (probably still has dry spot at 2mm of throttle)

PJ; 35 to 38. FS = happy at 1-1.5 turns.
did a test of checking the popping on the overrun and less at 1.5 turns than at 1 turn.

PJ; 38 to 40. FS happy at 1 turn again.
test;
hesitancy back again, large overrun single pops. rich somewhere!


Thu 16th May
first run, excellent bar 2mm dry spot.
PJ40 big drop past 38 and 35 to 33. the leanest! FS happy at 1 turn.
test; lot better at 2mm.

needle C3 to C1
If you snap the throttle and miss it, it never catches up, but if you snap the throttle it's a monster. midrange affected (poorer) but the top end in 4th and 5th loved it.

which do i raise to make sure I don't miss the nsnap?

PJ; 33 to 35. FS happy at 1.5 turns.
test; lovely snap! not quite nice higher.

Needle C1 to C2 (richer)
test; midrange back. bang on. no surging, no turbo, no two stage, no snorting, no popping on the overrun. starts straight away.

finishes;
MJ; 185
MAJ; 1.5
Needle K58 special
Clip; 4 now down to C2
PJ; 35
Slide: /50
FS; 1.5 turns


testing that is left.
because on a previous thread I pushed myself to test at the end of the day and the dropped the atomiser from DR274 to DR272 and really improved the starting, and also because the PJ is so low at 35: I want to see if it'll take a DR270 and also what happens to the PJ. also, to see if the starting doesn't become better still.

I wanted the jetting to end up in the "middle" well the atomiser is the halfway one but so is the DR270....there are 6. but the PJ is lower than I wanted.

is the PJ suppresed in anyway by the .4 PAJ or is it right that both are small.

I also should try some top end stuff but on road gearing. i don't like this type of testing anymore. Too fast, too noisy, too old!

also, I have put a PROPER BLUE KEIHIN bellmouth inwhat is really the dell orto air filter adapter (AFA) that I have called here "the bellmouth" but it isn't really. this should net a good midrange improvement.

here is what i did to the choke;

look at the size of the hole the alloy bung filled. the choke still only wants 1mm of lift at the lever!!!!

I really wanted that Japanese high idle. I have only ever had it once and not sure how to get it back!

Taffy

Taffy

so nobody see what they think was my continuous mistake?

well, I'm feeling better that it isn't so obvious. would have thought Ned would get it though....

Taffy

Huskyfatman

Thanks for the info Taffy!

I’ve had 4 bikes with Dellortos, none Husabergs, but they’ve been pretty good to me. I find them to be less finicky than FCR’s which need constant pilot jet cleaning due to crappy fuel quality and are way more sensitive to jetting. FCR’s definitely have the edge in outright performance, but the old Dells are fine for a trail bike.

I’ve had to replace a couple worn needles on my old 610 huskys, but have never had to mess with the jetting much though they seemed a touch rich. Once you learn the starting drill they do just fine.

Same for the Rotax lump in my old ATK, just clean the Dell every once in a blue moon and it mixes great. Plus the handlebar mounted choke and estart makes it easy.

I for one like ‘em!

ned37

maybe, but i felt like a nap after the second chapter of this book

Taffy

I only simplified it for you Ned..... it has an inbuilt age allowance!

Taffy

ned37

tinwelp

Taffy,
keep up the good work. I'm confident you'll get the perfect result in the end!

Personally I'm quite happy with the Dellorto on my FE400. I've FCRs on other bikes, and although they're excellent carbs with fantastic adjustability, they are very far from perfect. Huskyfatman hits the biggest nail on the head: pilot jet blockages. Don't ride an FCR equipped bike for two or three weeks and it's almost guaranteed you'll need to strip and clean the pilots. A massive pain in the arse on something like a KTM twin.

Choke performance could be better on the Dellorto, but honestly, if it starts on the button after sitting totally unloved for three months, what more could you ask? Fuel on, choke on (standard Husaberg fitting, no fancy bar-mounted lever), crank for a few seconds, then turn off the choke whilst continuing to crank... and it fires straight up on the next compression event. Hold the throttle open a smidge for a fast idle until it's warmed through for maybe 15 seconds, then it'll idle hands off. No drama. When fully warm it'll accept a wide throttle blip without 'bogging', and performance is great on- and off-road.

It took me a while to eventually find this happy state of affairs, and I'm the first to admit it's far from ideal fuelling (being a touch rich in the mid-throttle, mid to high engine speed range), but it's good enough.

How did I get to this point? I followed YOUR guidance in the wiki as a starting point, and experimented with small variations of jetting. The only thing I didn't bugger around with is the slide cutaway, which to this day remains standard for the Dellorto 38.

If you're interested, I'll pull my notes and post my current jetting. If you can improve on that, I'll definitely give your suggestions a try.

Thanks.

Cheers... Paul