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June 15th, 2019, 08:23 AM   #1
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I Ride: Husaberg FE501e 2003
Dell orto - just about everything was wrong....or was it the needle all along?


i don't very often start a thread here now. But I think those of you with a 1990-2003 bike may well be very interested in following the workings through this thread.

So, the target was easy starting which has been achieved with the 'Easy start' kits. all those with round slide Huseys can start them now with this kit. BUT, it doesn't change the low speed running, the 'snorting' through the air filter that indicates usually snort = lean. does your do it? yes? well, they all do!

I decided to use an FE501e from 2003 I had in stock, I could see an alternative con rod to help keep thses bikes going but felt that i had to be the Guinnea Pig for it. so I dropped in the XR400 rod with my stepped pins that i had had made and knew that the first tests were for the main jet (MJ) and that meant flat-out! so "hello con-rod maybe?"

here is a list of what the various parts of the carb do
this has an effect on all areas but mainly top speed or 6th gear rolling on.

this introduces air to mix in with the MJ. it sits at 6 o clock under the belmouth. it works the nearer the red line you get. NOT maximum power. it starts just before maximum power but then goes to the red line.

it fights the MJ. it has the most effect at the red line. so it effects maximum power. if you have a big MAJ you must overcome it with a bigger MJ. so it's real job is to extend from maximum power to the red line. to make more useful power.

this is 4th and 5th gear roll on.

PJ;part 1.
this has to help with starting a little but it's main job is 2nd gear from 1mm of throttle to when you change into 3rd gear.

It is affected directly, 100% by the slide cutaway and the PAJ. not a little but they ARE the PJ, they decide what the PJ will be. that means, that no matter what you play with, if the slide is wrong, then the slide says which PJ and and so does the PAJ.

The PAJ;
this is at 7 o clock under the bellmouth. The air that goes through here starts slowly and grows to a fast maximum. a PJ has to 'tango' with it as a partner. if you want a small PJ then you need small air.

the size of your PJ can be small but if the PAJ is large then there will be a point where the little 35PJ is at it's maximum but the big PAJ is drawing huge air. just as it hands over to the needle, there will be a dry spot because it is all air and no fuel.

Slide Cutaway;
the size of this dictates the size of PJ. it can be as little as 3mm or as much as 6mm. Lineaweaver used 7mm to overcome some problems...

it has two jobs, the first is to start the bike, the 2nd is low speed in 1st gear.

a small cutaway, will make the air go through a small mouth at the front and an engine has to - like you sucking air to breath through a straw - it has to suck harder!

if it sucks harder, it creates a fantastic vacuum under the slide and fuel is sucked up extra hard and fast. so a /30 slide sucks hard and a /60 slide sucks soft.

now, this is just the air speed we are taliking about here. if you have done 'blow painting' in your art class, you will know that you can blow gently and no ink comes up the tube. blow harder and you get a nice ink spray, then just a little harder and ink is everywhere and dribbling down the canvas.

greater air speed gathers more fuel too but it is NOT in ratio. it ramps up.

Dell orto - just about everything was wrong....or was it the needle all along?-vacuum-section-drawing.jpg

The vacuum under the low slide sucks fuel earlier and harder so you cap it by making the jet smaller. when the inlet valves close and crush that mixture up, it is going to be the same as lazy bones on the right, the bigger slide cutaway. at the beginning of the air going through and under the slide, it is so slow, no fuel is sucked up! at the end as well as the air slows down, it also doesn't suck fuel up, yet that is air with no fuel mixed in so we must have a larger PJ so that in the middle, at the peak, loads of fuel is in the air and again, like the small cutaway, when the inlet valves close and crush it all up, guess what? it is exactly the same mixture.

the same mixture via two different ways of doing it.

So by picking the slide and PJ we can start the bike. so why the choice you ask.

well the slides job is now done but the real reason we have the PJ is for 2nd and 3rd gear low speed stuff.

PJ 2;
so while we have a choice of slide and PJ for starting, there is only one PJ for low revs - the right one! so you would pick the right PJ here, then pick the slide to go with it for starting. at the same time, the PJ has to be carried on the boat via the air through the PAJ.

so what are the rules in this liquid mess?

Thy PJ will have a matching PAJ
Thy PJ/PAJ need the right slide height to start the bike. it's the slide that changes
the Fuel screw wants to be out 1 to 1.5 turns. it wants to start to suffer as you turn it inwards to close it, from .75 of a turn and wants to stall from .25 to closed.

we still have 2 more to go (or 3, or 4....) so next is;

this is the tube the needle goes up and down in. The AB series that husky use were made with a tube sticking into the air stream and are known for decent low speed and starting, they are not for performance.

the DR series that the huseys run are flush with the bottom of the venturi and are known as a little poorer on starting and a little better on power.

anyway, an atomiser is all about resisting fuel going between it and the needle straight. as the taper starts, the atomiser looses its say in what happens.

so you think you got that? notice i did NOT say; "an atomiser is all about the gap between the needle and it" because it isn't.

OK here's a mentally visual test.
a 12" waterpipe is letting water out the end in hundreds of gallons a minute. a man drives a tractor with a telegraph pole 10" diameter and forces it 10 feet up the pipe. you and i can now go over and fill a bucket up once every minute.

but if the tractor takes a 10" paint tin lid over to the pipe and put it inside the end, the water barely stops, dozens of gallons still exit the pipe. yet the blockage in area size (known at school as the CSA or 'cross sectional area') is the same?

so the same becomew true of the needle and its needle straight.

If I have the needle on clip 1 (leanest. clip at the top. pointy end down), I maybe have 12mm of straight in the atomiser, but if I'm on clip 4, i only have 8mm in the atomiser. let's sort the needle out first. a clip and a gap are worth about 1mm so 4 clips and 3 gaps between them are about 4mm.

so let us say we moved the needle for best midrange gradually during testing and we go from C1 to C4, we are now letting more fuel by the needle at idle too! there's an argument that C1 is with one atomiser and C4 is with the next size down/smaller atomiser!

on racing two strokes, you changed the needle one clip and you changed the width of the needle as well, just to keep everything other than that midrange change you were after - the same.

Fuel Valve;
this is another phuq up but this time it is a dell orto one. as if we don't have enough phuq ups by husaberg, we gotta have them by dell orot too! the float arm is meant to cut off fuel with the arm parallel to the body join twixt carb and float bowl. alas, the fuel valve is used in many carbs with many floats and the fibre washer underneath the Fuel Valve is critical to this. the 300FV that we use in all Husabergs comes with anything the Italians can find. when new, it is red and 1mm. it crushes to around 0.8mm. In the 40mm carbs this is fine but in the 38mm carb, it needs a thinner one. around 0.6mm. But then you'll get a fuel valve with a 0.6mm fibre washer in it and the problem goes the other way.

Dell orto - just about everything was wrong....or was it the needle all along?-steyels-float-height.jpg

a high float arm causes burbling and a low one like the photo means flat spots and coughs and it is all dell ortos fault!

this is my name for rich at idle; 'ber-ba-ba-ber-ba-ba-ber' there are two noises. one is the 'purr' of the engine but all the time in the back ground you can hear it; 'ber-ba-ba-ber-ba-ba-ber'. it is so normal, you THINK it is normal!!! then one day you have the correct mixture and the noise is gone and you realise you were 'suckered'. p

Fuel Screw (FS)
this is the one on the front left corner of your carb, just over the top of the exhaust. if it is closed = it leans the total mixture. if it is open = it is enrichening the total mixture.

the FS is a mixture of what comes to it from the PAJ and the PJ. the job is already done when it gets there, it can't change THAT ratio.

but the collective 'pilot mixture' is way richer than the stuff being drawn through by the needle and MJ etc on the main circuit. its collectively richer so we use this screw to add to the main stream.

visualise this.
helicopter over a river that is a little muddy - but you can still see the bottom! - in from the side comes a stram, not a lot of water coming down this stream BUT, it is as muddy as hell! it is thick with mud.

so the pilot circuit, while it operates, "tops up" the main circuit. without it the bike is designed to stall. with it, we use it to top-up.

1.5 turns of the FS is considered the right amount of turns out IF the PJ/PAJ ratio are correctly complementing everything else. but of course, the atomiser can be worn, the needle on C1 or C4 as said above. then we have winter and summer....

this really brings us to the last on here and that is the "top bitch in the show", the "queen bee", "she who will be obeyed". The Needle!

The Needle
if we set a table in a big function hale, all the K,F,S, glasses, napkins-the lot....all the chairs are bang in the middle of the table mats, then I go to the end of the 100 foot table and pull the undercloth 18", what have I done?

is there anything now right about the table? nope! and that my friends is the phuqing needle the total BITCH!!!!!

change anything about the straight of the needle (remember the paint pot lid above?) the beginning of the taper start (remember C1 to C4 above) and everything is out.

we're not helped here by the fact that dell orto made around 90 needles all known as the K series. The K9 is the worst, its a real dog (sorry, I'll get my coat ), there are small clutches that make patterns but nothing as systematic as that by keihin...and we suffer because of it.

luckily for me, a Go-Kart team had done a programme which they sold on to Eurocarb here in the Uk and they sell this simple little programme on. all you can do is profile one needle v another and go up and down clips. the other two things it factors in is the atomiser but that is misleading and the MJ, which is a joke. But the needles are what it is about. This was very helpful because without it there was nothing....thanks to that kart team!!!


Thanks from steve, mars, Huskyfatman and 2 others

Last edited by Taffy; June 15th, 2019 at 08:43 AM.
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June 15th, 2019, 09:33 AM   #2
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fuel valve - as they get older, the fuel valve spring weakens and just says 'phuq it' and simply lets more fuel in.

fuel valve fibre washer - as said, the FV fibre washer size can be 0.6, 0.8 or 1.0mm. all these change the straightness of the fuel valve arm.

add these two togethr and you have a toxic problem for anyone. this is enough to halt any bike from starting.

The carbs up to 2001 on the waterpump-on-the-head engines often came with a /50 slide cutaway, yet all the bikes from 2001-2003 came with /40 and the FX and FC470s came with an incredible /30. no chance! more later on the slide cutaway....

these small cutaway engines needed a 33-38PJ for starting but needed a 40-45PJ for low speed running.

the choice of needles is a shocker and sadly, Husaberg realised that they needed an 'early taper start needle'. Both the K51 and the K35 are early start taper needles but the overall design is wrong. it would seem that the R & D people just didn't know how to jet them correctly OR that the cheif buyer kept getting a bargain price on the wrong specification carbs? very strange.

another problem is the choke. when first trying a variable choke, it took 4 days to realise that the bike wants the choke cable pulled just 1mm on the cable.

each day i tried different positions with no joy and each day i ran the battery flat just to have to charge the battery for 24 hours again!

eventually on the 5th day i started at 1mm and 'caught' the engine. it fired and the rest as they say is history!

the reason it is another phuq up is because the hole for the air to go around, the circuit if you like; is 5mm ID. now that is a set amount of air and a close look at the choke jet options in the purchase manual shows that you can buy choke jets from #40 to #155.

the Husaberg is down for a #50 choke on the earlier engines and a #45 on the later ones from 2001. Now the 5mm hole makes sense! if i had a #155 choke jet I would ALSO want a 5mm hole through which the air could go and SUCK it up!

but out of 46 choke jets, we use the second smallest and that little #45 is giving its maximum through its tiny hole with just 1mm of lift. the air that goes through isn't even the cross section of the middle of the hole, it is the little bit across the bottom. the air is going through the shape of a 'smile' 1mm high.

if you keep pulling the choke lever, all you do is introduce more air! more and more air for the same choke jet size.

you may question if a larger choke with more air could match in ratio higher up at say 2mm of lift but the overall package is so rich, the bike wants to stall after 10 seconds.

slide cutaway
But as said previously, it is the slide cutaway that has a pre-destined PJ/PAJ to go with it. and at /40 the PJ has to be pretty small and in the low medium 30s. yet they want a low medium 40s PJ at low revs. change to a 42PJ and the bike can't start the bike because that 42 is too rich. change it to a 33 or 35PJ and it starts but can't rev because the PJ is too small.....thus the snorting (meaning lean) that most of you know about.

if you take the bellmouth off and look at the front face of the carb, you'll see two brass rings down the holes. the hole at 6 o clock is the MAJ and that is usually 1.5mm ID. this is enormous. it is fighting the MJ all the time at high revs. they just fight each that simple enough for you?

the PAJ comes at 1.0mm ID. this, for the pilot circuit is also; enormous! if this has a matching 50PJ then happy days! but if the PJ is a 40 then what happens is that as revs increase, air speed and suction increases too. more fuel, faster fuel gets drawn through the jet, but suddenly, the small PJ levels off at flat out, just like running next to a 6 year old! but the PAJ carries on faster and faster and changing the mixture to lean!

there is a 'sour spot' where this can make the bike vibrate for 200-300 revs and then luckily the needle takes over and it is all forgotten. In the Uk, you can feel it coming out of a roundabout behind a few cars and instead of changing gear into 3rd you hang on in second and the bike sounds terrible!

we haven't really said much about the shape of the needle here as it is just too complicated. more on the needle later....bitch!!!!



Thanks from steve, mars, Huskyfatman and 1 others

Last edited by Taffy; June 15th, 2019 at 11:19 AM.
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June 15th, 2019, 11:08 AM   #3
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Brilliant read. Fantastic wealth of knowledge there, thanks for taking the time to write it up! As you may remember, I have your complete carb kit running in my bike, and to me it runs great! easy to start, awesome power, but I'm grateful for a detailed write up on how each adjustment affects another, as I can now see if I can find any improvements on what I've currently got!

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June 15th, 2019, 12:47 PM   #4
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I Ride: Husaberg FE501e 2003
original set up is;
MJ; 185
MAJ; 1.5
needle; K51
Atomiser; DR272
slide cutaway; /40
clip; 3
FS 2.75 turns open
PAJ; 1.0
choke #45

carb was changed for easy starting to;
needle is K51
clip; 3
Atomiser; DR272
slide cutaway; /50
FS 1.5 turns open
PAJ; 1.0
choke #45

alas the next 10 test runs gave nothing but confusion
Dell orto - just about everything was wrong....or was it the needle all along?-paj-maj.jpg
my young mechanic had put these two jets in the wrong way around. I couldn't tell my arse from my elbow as i worked on needle and MJ. eventually I took a peak at them and found them wrong and so swopped them. NOW we can set to work on it!

Fri 26th January 2018
slide changed from /50 to /60
corresponding PJ change from 45 to PJ52. PS = 1 turn
report; runs sweet! 0.5 turn (in) of PS stallsrevs sweetly! test run and unbelievable att low revs. sliky smooth but dry at the bottom and off idle plus no power. PS turned in to 0.75.

try DR270
stutters at low revs. popping on overrun.

DR270 to DR274. PS to 1.25 turns
smooth all over but backfires oin mid and low on overrun.

Sunday 4th february
first run aswas. PS; 1.5 turns. stalls at .5 turns excellent!

drop C3 to C1
terrible, starved, judder then turbo

C1 to C4.
beatiful, but open throttle 2mm and it moves stage 1 then to a stage 2. no backfire

C4 to C5.
cardboard under clip. popped on overrun but finally no hesitation.

/70 slide? DR274? (different) needles?

6th Feb.
changed from standard carb with 1.3MAJ and 95PAJ to carb with jets in the back. 150 (1.5) and 100 (1.0) fitted.

DR274 to DR276 (the thinking is that she's starved off fuel due to too mush needle straighht in the hole. so if you can't lift the needle any higher....make the hole bigger!)
test; PS stalls at 0.5 out = excellent. pops on overrun otherwise excellent.

needle down from 5 to 3.
test; very smooth

drop needle, C3 to C2
a little 2-stagey off idle. very smooth and powerful pops on overrun.

Wed. 7th Feb
needs to be revved to keep running nice off choke.
.75 FS. hates anything over 1.25 turns. but also stalls on anything under 0.50 turns....very narrow area.

two changes (breaking my rules)
52 to 58PJ and /60 slide to /65 slide.
didn't even ride it, it just snorted when blipping the throttle so no chance if riding!

58 to 55PJ
had to raise the idle (bad news, so bike doesn't like it)
dry sport at 2mm of lift.

raised needle from C2 to C4.
nice. slight surge off idle. otherwise excellent. hardly popping on overrun.

conclusion; will it pull a bigger PJ if I open the PAJ to 1.25? then I can drop the needle.

Thurs 8th feb.
55PJ up to 58. also PAJ up to 115 (1.15) choke down from #50 to #40.
starts as if lean then suddenly speeds up on its own (Japanese style)
FS stalls at .25 and again at 2.0 turns.
rode great! dry at the bottom, ace in the middle.

C4 to C3 (leaner-dropping the needle)
test; ran great. just as above

C3 to C2 (ditto)
flat spot at bottom end.

conclusion; whatever i do with the K51, i have a HESITATION at the bottom. I've tried everything to juice it up. needles with cardboard under them. massive atomisers, huge PJs at 55 or 58, hhuge slide cutaways...was close to a /70 cutaway a few days ago. Can't do anything with the K51. I have about 12 needles from around 2002-2003 when I first got the FE400e.

using my own drawings on a piece of paper and different coloured pencils (at the time) the K9 (a bit of a dog....) looks the best I hold.

K51 to K9 and clip 3 (of 4)
the rest the same.
test; ACHIEVED!!!
FS happy at .25-.75 out ran great, no snorting! stalled on overrun twice. no flat spot at last!

Dell orto - just about everything was wrong....or was it the needle all along?-k51-c5-v-k9-c3.jpg

this is only the beginning!


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June 15th, 2019, 02:52 PM   #5
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So the above diagram shows a reduction in the needle taper start BUT the needle is narrower. The K51 is the only needle with a 45mm taper start. many others are around 36mm. the K35 is 43mm taper start.

But the K51 is the only needle out of the 90+ needles that is wider than 2.50mm. it is 2.52mm. taking the paint pot lid theory, I just could not get rid of the hesitancy. but allowing more fuel up the side by using the largest atomiser and now this thin needle that was 2.45mm (on the straight part) now we are in business!!!

So now, we have a new mission


how low can you go......

Sun 11 february 2018.
Always start with the old settings unless it can't be avoided due to massive work needing doing.

MJ; 195
needle; K9 (very thin on the straight at 2.45. lots of fuel getting by)
Clip; 3
atomiser; DR276 (the biggest)
PJ; 58
FS; .75 turns out
slide cutaway /65
PAJ; 1.0 (100)
MAJ; 150 (1.5)

C3 to C2 (leaner)
ran sweet. idle liked it.
C2 to C1

DR276 to DR274
great but no snap wheelie

keep the DR274
raise the needle though C1 to C2
test; better snap wheelie, snorts at bottom end, difficult to start.

Monday 12 feb
back to C1 and back to the DR276
silky smooth, not so easy to start warm (note: bikes need to be lean to restart when warm and baby, she ain't lean right now!!!)

try and reduce something else. ah! the
55PJ to 52PJ
also /65 slide down to /60.
1.15PAJ down to 1.0PAJ
test; not as smooth but very good. slight 'hunt' at top of PJ and off idle. FS out to 1.5 turns and easy to start.

back in the workshop
52PJ down to 48PJ
bike hunting and snorting = hated it!

14/2/18start with a 50PJ so = 48 to 50PJ.
needle C1 to C3 9richer)
FS = 1.5 turns
unridden. not happy.

test run
slight snort off idle but when warm is gone (so only just enough fuel for cold satisfaction is what I'm saying). lots of popping on the overrun (means several things are wrong). I'm getting up to my neck here in sh*&.

C3 to C2
clear snort off a closed throttle but midrange is ace. ran great, lowered idle (a great sign) no backfiring on the overrun.

C2 to C1
FS = .75
ran great, dropped idel again. popping back. 6th is dead flat at 120kph.

Time for a new needle I think. this K9 taught me that the K51s width was all wrong. the K9 starts narrower therefore the taper angle is not so sharp. I need a needle with a similar width and can help me lower the juice even more. the bike is dead at the top end. this is because the tip of the needle is too fat. so a second taper would be nice.

Dell orto - just about everything was wrong....or was it the needle all along?-k9-c3-v-k67-c5.jpg
so I chose the K67. mind you, I bought a bloody handful of various needlescoz I wasn't sure what was going to happen.

note how the K67 is even thinner (2.44) on the straight than the K9 richening this area and then a littl leaner through where the PJ would be and then note the little flick at the top meaning the needle tip thins out quickly which should help 5th gear.

K9 out. although the last run was C1, the K67 has to be two clips up to be the same so from K9 at C3 I start at K67 C5. luckily it is a 5 groove needle this one!

test run one
Stunning! so light when moving off! the engine wants to help! come on, lets go!! you dare just drop/dump the clutch. no snorting, zapped it! taller gearing needed for valid testing.

dropped the needle (lean) C5 to C3. PS is still just .75 turns out.
test; slight vibration off closed then awesome, incredible turbo all the way to the top.

now a mistake.
50PJ down to 48PJ.
FS is now 1.5 turns.
test; starts on button, no popping on overrun, slight snort at low revssurges even though you just touched the throttle at low revs....goes off on its own.

C3 to C1 (may as well see a real difference as a 'maybe')
test; slight jerkiness throughout when opening the throttlein PJ area and then TURBO.

so C5 ace, C3 'OK', and C1 Jerky....more fuel needed at the end of the PJ?

Time for a new needle and I've seen one. it'll be even thinner on the straight and now we're getting real thin! the next one is a K68 which is just 2.42 wide.

I fit the K68 on the ame C1 but it is the equivelant of lifting the the last needle one clip (richer).
K67 C1 to K68 C1
testsame Fs. ran fine, snorted at low revs

C1 to C3 (so compared to the K67 its like lifted 3 and narrower on the straight. i'm having to richen the bottom AGAIN!).
a strange turbo surging from closed (like being catapulted) then some soft surging, no snorting at all. more of a BWOARRRR)

C3 to C2 (leaner)
nearly surges. but clean, ran well. PS 1.5 and dies under 1.25 turns. hyper critical.

a look at the needles available says that the K68 was simply the wrong choice and that the K66 is better, no need to worry about going back to 2.44 width, this I now know can now be dealt with.

let's see all these last 3 needles on one sheet and all on the same clip. I also add the K67 a second time still on C5. I've picked C2 for all of them.

Dell orto - just about everything was wrong....or was it the needle all along?-k67-c5-c1-k68-c2-k66-c2.jpg
the two to note are the K67 C2 and the K66 C2 in pink. they have the same taper start but the K66 gets leaner the further along the needle and then at the last moment, BANG, it is richer! that narrower tip should allow a leaner MJ when i test it too. (blunt wide ended needles act as a wall for a MJ so the size has to be increased, and then there's the opposite too...).

so to recap
MJ; 195
needle; K66
Clip; starting on C4 same as K68 C2.
FS; 1.5
PJ; 48
atomiser; DR276
slide; /60
MAJ; 1.5
PAJ; 1.0
slow starting, smooth take off. wheelies, no popping, revs iout really fast, snap is TOO good!

C4 to C2 (lean)
test; snort, hovering, all at the bottom, then excellent. C3 next.

24th feb 2018
C2 to C3 (richer)
Gearing 16x 48T
excellent. good off the bottom, two stage go so perhaps C4? strangely, dry at 81kph in 5th? (probably needle tip bu I let it go for now. it'll tell me more if i need to know about it?).

C3 to C4
no snorting. pulls the same as C2 and c3. idle dies under 1.0 turns FS.

C4 to C2 again
test; occasional heavy backfiring.

then something I shouldn't ever do but I think i know what is needed here. we are getting the needle in the ball park now but if I don't get the MJ right NOW, it'll be like pulling that table cloth 18" I mentioned.
195MJ to 190MJ. also
C2 to C5 - richer (to counteract the MJ coming down and to go back to what was working when C4)
DR276 to DR274 atomiser
test; better top end, turbine smooth, no dry spot, popping on overrun, FS; 1 to 1.5 turns out best.

48 to 50PJ
test; heavy single popping on the overrun. lean? complete absense of any vibration from the engine (a very good sign)

7 march 2018
very cold. ice cold.
50 to 52PJ
test; heavy backfiring (well rich) just .75 FS is happy (rich then)

Time to check the MJ again(so take it seriously now!) and another needle looks good. it is the K61. this is 2.44 at the root so the same.

let's look at it against the K66 it replaces and also its timely to remind you of what we started with. The K51 in C3 and a DR272.

Dell orto - just about everything was wrong....or was it the needle all along?-k51-c3-k66-c5-k61-c5.jpg

as can be seen, the K66 and the K61 add a lot of juice at the top end, they are way richer than the K51 at low revs and idle. indeed, the K51 is nearly off the graph. you lean basted!!!

now remember that the K61 and K66 are on C5, if they should ever drop to C1 or C2 they will be way leaner than the K51 having only just a second ago was at idle having been way richer.

you think I'm getting nowhere don't you?


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June 16th, 2019, 12:33 AM   #6
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So on a mild Wednesday evening I fitted the K61 after the intitial run and started safe +1 clip.

8 march 2018
K61 needle (was K66)
clip 5 (+1 from the K66)
50PJ (was a 4
Idea to start safe and then work down.
test: starts well, runs beautifully!

10 march 2018
Did some top speed tests again as the bike is getting closer and closer and the needle tip thinner!
190MJ to 185MJ
test; better everywhere, gained 5KPH everywhere except top where it can't coz its dirtbike gearing.

drop needle C5 to C3
bike ran nicely, PJ a little weak, but needle brilliant! top end not a strong though? (strange?)

3 changes at once but all in seperate areas so easy to check otherwise I shouldn't.
185 to 182MJ
C3 to C5 (richer)
50 to 52PJ
test; Excellent! the 52PJ makes it really smooth low down, no vibration.

I then do 5 tests with a /65 slide cutaway and a massive 60 and 58PJ. down on the atomiser from DR274 to to DR272. the bike likes the DR272 but I can't work out why? just off idle it judders too and fro in what I call 'Morse coding'.

then came 5 tests on the 23rd March 2018. lowering the needle from C5 to C4 to C3 but with the /60 slide back in. it seems that if you move the throttle like a fraction it goes werrrr....waaah!!!!!! all on its own. this I call 'the turbo effect'.

the set up is now
.75 FS
/60 slide
MAJ 1.5 and PAJ 1.0.

Studying the needle charts, there is nothing left i can buy. the K61 is the only one. there is one that would do if I'm prepared to put washers under it and call it 'clip 5' or clip 6 & clip 7 etc. it is the K58

even to compare them, i have to put the K61 on clip 1 and the K58 on clip 5. just to see the similarity.

Dell orto - just about everything was wrong....or was it the needle all along?-k61-c1-v-k58-c5.jpg

so looking at this chart, you can see that the K58 needle tip is REALLY thin and will boost 4th-5th gear no end. that is with it on the maximum (rich) of C5 and the outgoing K61 on C1. BUT IT WASN' was on C3. so now to match it I have to pretend i have 7 grooves. all i find is some cardboard in the bush and make a quick fix 'washer' to lift the needle up.

Dell orto - just about everything was wrong....or was it the needle all along?-20180204_133334.jpg

27 March 2018
K58 (2.46)
clip; so called "clip 7".
FS; 1.25
slight turbo off closed. PJ area rough. really powerful though! 130kph on a whiff of throttle compared to before! poor starting.

turns out the choke jet was blocked.

so we now have a great midrange and top end but still all kinds of things are happening at lower revs. 'turbo' (see a little higher up), 'two-stage roll on'.

28 March 2018
DR272 still (note this point for later. this test and the next test. I didn't see it until the end of testing. note the DR272 to DR276)
FS; 0.5 out
PJ;52 to 58
proper washers underneath clip and so called C6 now. really trying to juice up the bottom for that creamy smooth moving off from the kerb etc.
smooth with the 58PJ.

DR272 to DR276
PJ58 to 52 (the atomiser is expected to pass more fuel at low revs so balance it out by dropping the PJ).
runs great but lean on the PJ area. dry...
FS now 0.5 turns.

PJ52 to 58PJ
smoother off the bottom. idle is nice and steady. FS stalls from .25 to closed (so VG then) a little dry above the PJ?
ideas; atomiser down? /65 slide?

Good Friday 30th March 2018.
tried around 8 tests. I tried gradually making the atomiser smaller through 274 and 272, also the slide went from /60 to /65 as well as at the same time a 58PJ down to 55 and then 52. It snorted at low revs with the 52PJ. It turned out that putting washers under the needle to make C7 as well as a 55PJ and the DR272 atomiser were the best set up with the description;
I went down from DR274 to DR272 but up on the PJ from 52 to 55 at the same time and then wrote; 'why not try the 52PJ with the DR272 as well..."but there's no point" I replied to myself. Oh dear!

so this was the best i'd had though when it was on C7 and a 55PJ. I wanted to get the jetting in the middle of what you can buy and the DR272 is but a 55PJ is near the top extreme and so is a /65

So on Easter Monday 2nd April I tested to see if I couldn't bring down the slide and PJ in relationship down and down. I also changed the PAJ for the first time to a 75 (so .75) jet. the result of 7 tests was disappointing.

But three tests are revealing
DR274 to Dr272
/50 slide
test; burbles like hell (rich) low speeds

DR272 to DR270
bottom end blubbery

even tried a DR268 and i called it 'after a little hesitation it was fine'. but i wasn't getting anywhere with it. for the first time I did some testing and got nothing back other than the knowledge that a low slide and PJ wasn't going to work.

It was looking more and more like the low end problems were only solvable with the needle on C7 or with 6 washers a kinda "C8".

Wednesday 4th April 2018
5 more tests with the atomiser now down to DR268 the slide down to a /50 and the PJ down to a 33 at one point. ALL had their problems but the small slide cutaway and small PJ with a small PAJ wasn't working. C7 was!



Last edited by Taffy; June 17th, 2019 at 12:14 AM.
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June 16th, 2019, 02:34 PM   #7
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Wow. Taffy that’s a lot of fantastic info to take in .I have a your spruce up and tune up kit which I am working on now. It is ten times better than before but I need to do more work on it. This info will really help when I have understood it properly (Black art of carburation).
FE501 2003
Back to reread it again and again lol
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June 17th, 2019, 04:37 AM   #8
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So the story at the moment is that the K58 works as long as it is lifted up 2 or 3mm.

that there are a series of 'turbo' and 'two-stage' and just about everything else you can think of at low revs and off idle.

It appears that as long as you throw a 58 PJ in - which is enormous! that you get somewhere.

the 58PJ is making up for something as there are many circuits doing a little bit each at low revs and on a closed throttle.

it's not hard to spot what it is....the needle.

the taper start on the K51 is 45mm from the tip. it is 43mm on the K35 yet on the K58, K61, K66,K67 and the K68; it has a taper start at 36mm. that is 7mm lower. THIS is why the needle needs lifting almost out of the top of the slide!

jetting is like a pile of books, if each part does its job right nothing happens but if the second and third book are over one side then the 4th and 5th book have to be the other way or the books all fall down!

The next idea is that if the needle straight is wider but the rest the same, the bike will idle leaner but correctly allowing that 55Pj to stay.

the K58 is 2.46 but the K48 is identical bar the straight which is 2.48. the leaner straight allows instead of 0.75 turns of the FS, for iot to be 1.5 turns.
THEN I can keep that 55PJ knowing it only helped the low speed and didn't stuff it in on the idle as well. well it does sorry BUT the needle straight withdraws the offer of help as the gap is smaller.

I do 5 tests and on each one I reduce the PAJ from 1.0 (100 idle jet) down through 90, 80, 75, 65 and then finally; 50. a 50PJ representing 0.5mm in diameter. now remember; a 50 hole isn't 50% smaller than a 100 hole. if you have to ask then you weren't too good at Maths at school.....

Dell orto - just about everything was wrong....or was it the needle all along?-k58-c5-v-k48-c5.jpg

So the K48 is fitted on C7, the /65 slide, a massive 55Pj still. But this dryness at the bottom persists. after 4 runs of play on the 5th April I gave it up as no good. nice theory....

I check the ignition timing again for any imperfections and decide to advance it just 0.5mm. there is no noticeable difference but now it is correct again.

the idea now is to go back to the K58 C7 and a massive PJ at 55 and therefore the /65 slide. but now, I'll keep the 50 PAJ in the front face of the carb.

on the night before the tests, the Friday, i realised that i had tried everything else. it is in my nature BTW to go round the OUTSIDE of a problem and work to the middle and learn on the way.

several of my mistakes had been things I kind of knew couldn't really work but the problem is at the bottom end and that is the most complicated area of jetting. there are 5 or 6 things to change and all add a little to the feast.

This had to be the problem. The PAJ!!!! all along! yes, that's it!

I got up on Saturday 7th April and said to my partner; "100% gauranteed today. I'm going to knock it dead!"

So I started with
MJ; 185
needle: K58
atomiser; DR276
Clip; 7
PJ; 58
PAJ; now down to '50'
MAJ still 1.5mm
FS just .25 out. anymore and it is very rich.

test 1
ran fantastic. no problems.

test 2; 58 to 50PJ (only a small drop of 3 jets then! cocky sod!)
ran spot on. slight hint of dryness at 2mm of throttle. FR now stalls from .75 to closed as it shoud do.

test 3; 50 to 42PJ (again only a 3 PJ drop. the arrogance of it.....!)
excellent! still only a slight hint at 2-3mm of opening. FS at .75 to 1.5 turns (spot on) no backfiring at all on the overrun.

i then wrote; could consider 33PAJ and 40/42PJ and also a drop to DR274 again". as you'll see later, I just miss being lucky yet again.

So that was it, that was how i finished testing in early April 2018. I then produced a kit named the "Bergbooster kit" just for the 2001-2003 FE501s.

I altered the spec from the above in one way which i shall not say here.

all along, I knew though that the needle straight taper start at 36mm up the needle was way too late. so I rode the bike for 11-months and kept a 48PJ in it, had a little 'hint' of dry at 2mm but otherwise it was super.

I enquired with my engineer about machining down the needle and was told that it would be so weak it would bow away from the cutter.

"try and do it by hand!" was the reply. So i set too and marked where I wanted material off the needle. got some "wet 'n dry" P600 and a little parts cleaner on it and wrapped around an old hacksaw blades and split the P600 between them. I then put the needle in the drill on the drill stand and proceeded to take off some material.

how much? I have absolutely no idea at all!

so how did it go?



Last edited by Taffy; June 17th, 2019 at 04:43 AM.
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June 17th, 2019, 11:52 PM   #9
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Originally Posted by gozzo View Post
Wow. Taffy thatís a lot of fantastic info to take in .I have a your spruce up and tune up kit which I am working on now. It is ten times better than before but I need to do more work on it. This info will really help when I have understood it properly (Black art of carburation).
FE501 2003
Back to re-read it again and again lol
well from now on you'll be able to see what improvements i have made since your kit was designed. I'm at the end of my 5th page of notes and there are 33 lines per page.

while the first page was fecked by the young mechanic a bit and the 4th page i went "round Will's house" double checking stuff (around Easter 201 it still represents 100 solid runs and 25-40 waisted.

just licking my lips to start rattling on about the needle I modified.


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June 18th, 2019, 05:29 AM   #10
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Post traumatic husaberg stress disorder PTHSD.

I prefer the dellorto to the kein. Not only does it fit in and out the bike it is easy to get at and jet. After spending years with Amal Bing and Mikuni the Dellorto was a puzzle till I got the Manual. Start with stock jetting then focus on main jet and work out how big using the choke and fuel tap to test at wfo. I went huge at195. Then I think 38 pj and as the needle wears out and so does the needle jet use the worn out needle with a new nj instead of sand paper. The 38 pj gave an average good performance not needing to replace the wearing needle and NJ all the time. The pj needed to be supported by regular new slides that were out and was the cause of flame outs that I think I still have a stock off new shiny ones. Despite Harley type idling and better idling on the kein I never got the kein to put out the snap and power like a switch that the dellorto gave. PTHSD
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