PHBG tuning issue

[br4inl3ss]

hello.
trying to dial in my dellorto 19mm phbg ds.
yes its on a 4 stroke, but most knowledgable people doesnt look on the 4 stroke forum so here i go.
or they just barely know what a phbg is lol. anyway. 

so the carb is with AN 262 so its in 4 stroke mode as it comes from factory.
i think idle jet is 30 or 32 i dont remember but going bigger doesnt solve the issue.
main jet is.... 85 i think. too small but doesnt fix the issue either.

the problem is on quick throttle action ( be it 1/4 or 3/4 or full ) it try to stall. if i hold it then it will stall.

hitting the choke at the same time doesnt help. think its worse but not 100% sure.
putting the needle clip at the highest position make everything worse. barely accept any throttle even slowly.
so it must be in the lowest position.
without air filter its worse.
turning the mixture screw counterclockwise seems to help but thats onlt like 1/2 turn before it falls out. and it also make idle way too rich.
a bit contradictory i know.

some rare people talk about changing the slide ? some talk about changing the needle ?
Simon a french youtuber did install one on video and he didnt change anything beside main jet.
he is NOT a liar. everythign he do is proven. but maybe he forgot to tell he had to change something after ? cant get an answer from him.
and his terrible community just tell to get a 2broke isntead. the usual french weird mentality.

both atomizer and needle are stock, aka AN 262 and W 09
as seen here  www.maxiscoot.com/fr/produit/carburateur-19-dellorto-phbg-ds-30512?vctype_id=13
its in french sorry. tried in english but all the specs disappear.
stock idle jet is 45 but thats wayyyy too big. as i see it even 32 is too big.

there is a shop that tried to help me because he did install phbg on 4 stroke in the past and alot of time. at a time he was doing 6-7 a year. thats alot for such a swap. he said he never had to change anything but main jet. liar or whatever ? i dont know. his shop is highly reputed here.

i do not ask for opinions but help. thanks.

[Lucass2T]

So if I understand right, if you quickly twist the throttle and then hold it at a certain position, it dies?

[br4inl3ss]

not 100%.
if i quickly twist the throttle it make a behhhh behhh sound like 2t moped. if i hold it then it'll die.
if i go slower its fine.

i'm sorry i have two videos i just forgot about them.

with air filter


and without air filter

[br4inl3ss]

UPDATE
this morning i upjetted main jet from 85 to 95. absolutly NO change for this issue.
the choke is useless. way too rich ( cold and hot ).
but thats probably because the choke is jetted for 2 stroke which require richer mixture.
that doesnt stop me from sleeping right now but its an issue to be addressed last.

re-tested today with a temp handlebar and throttle so we see better and easier to operate.
not installing it the proper way because at any moment i may need my scooter so id have to swap to cvk carb and fast.

the more i test the more i think its the needle. but which one to get.... is it too rich or too lean. thats THE question. i can buy one or two if i squeeze the wallet, not a set.

[log]

I think that you are lean at 1/4 to 3/4 throttle. You said you moved the needle. Did you allow for more gas or less gas? Also keep in mind that I'm not super knowledgeable, but that's just my opinion.

[br4inl3ss]

thanks. at least you dont answer to get a bee (2 stroke) unlike those terrible french people (well i am french but french canadian not french from france)

the best i get is with the clip all the way down.
the more i move it to the top of the needle the worse it gets.
so if i can focus right to understand properly (damn adhd), it's still too lean ?

what is misleading here is it doesnt seems to be throttle position related but how quick it change.
maybe its just an impression and you are right ?
but then again its fine if its slow. maybe thats normal when the needle is too lean ?
never experienced that before so.....

lets say i need another needle because it was just a bad impression and bla bla bla which is very possible.... and knowing i have the stock W9... then what needle would i need ?
W10 ? W8 ? W12 ? W6 ? ? ??
i would like to be able to buy a kit but $$$$$$$$

[br4inl3ss]

UPDATE
its definitively the needle (or the slide ? i dont know the effect of a different slide).
tried to go crazy on the main jet (115) because someone told me it was the main jet too small.
NOPE. no change at all on my issue. but its so rich it refuse to go over 5200 rpm. terrible.
he is stubborn its still too small...... the heck... i blocked him on the spot.

so the test i did according to a french guy on youtube (he also sais it was my main jet too small)
first i put back the HUUGUE way too big 40 idle jet.
he said 1 turn out from fully seated (while the whole planet says 2 or 2.5 ?)
then 1/4 turn in or out maximum, else the idle jet is too small or too big.
i told him 40 idle jet is way too big. he said impossible....
so i wasted my time with the 40, then 38, then 36... with 36 i was able to tune the idle but with 1.5 turn out. wrong.
tried with 34, thats acceptable according to his "1/4 turn max else jet is wrong wize". but with 1/2 turn out.

this guy tho... he knew i already had the correct main jet because it was running perfect WOT. he made me put a bigger jet because he was stubborn it was too small and said we must set mj FIRST. thand not false but i ahd that dialed in...

its literally impossible to set the correct idle with a bigger idle jet than 36 and thats well beyond "1/4 turn".
ofcourse its clockwise direction.

over multiple months ive had different input as to how much turn out from fully seated is correct on a phbg... some says 1, other says 2 some says 2.5... no way to get a real number. but apparently this change according if its on a 2 stroke or a 4 stroke. makes no sense to me but whatever. what do i know...

oh he also made me put the needle clip on the 3rd notch. i knew it would be worse i already tested all that but to get help you must do the nosesne because its always your fault else. and i was right again, the problem is worse the higher i put the needle clip.

yeah thats means its too lean. the best i can get is on the last notch down. its far from enought tho.

later today when the temp get hotter i will try a temp spacer inbetween the sldie and the clip. been doing this with cvk , no reason it wont work with phbg. its not a good solution i know. but just to test to be sure.

i still need input on what needle should i get... the previous one (w8) or the next one (w10), or w6 or w12...

[Lucass2T]

Do some reading on why most 4t's have a CV carb and not a normal one like 99% of the 2t's.

4t's suffer quite badly from sudden vacuum changes in the venturi. When you whack the throttle, vacuum disappears for a moment and fuel can't be metered right at that instance. Thats the moment it stalls.
They counter it by adding a vacuum controlled slide, thats called a CV carburetor.

Not sure how to counter stalling 9n a 4t with a non CV carb. But theres probably tons and tons of literature around on that specific topic.

Good luck👍

[br4inl3ss]

Apr 21, 2024 13:08:54 GMT -5 Lucass2T said:

Do some reading on why most 4t's have a CV carb and not a normal one like 99% of the 2t's.

4t's suffer quite badly from sudden vacuum changes in the venturi. When you whack the throttle, vacuum disappears for a moment and fuel can't be metered right at that instance. Thats the moment it stalls.
They counter it by adding a vacuum controlled slide, thats called a CV carburetor.

Not sure how to counter stalling 9n a 4t with a non CV carb. But theres probably tons and tons of literature around on that specific topic.

Good luck👍

yes.
thing is.. honda, suzuki , and i THINK kawasaki too had some arer model of 4 stroke quad ( dirtbike for zusuki ) that cames with PHBG from factory. so they can work on 4t thats 100% sure. thier setup if top secret info tho.

desactivating the accelerator pump on PoS CV carb doesnt cause this issue at all. tried that for days last season when trying to figure out my issue with msot carbs. the only thing desactivating accelerator pump did was run better when releasing and applying throttle at high speed. thats all it did. oh and it helped starting it the first time after installing a carb (squirt gas into intake isntead of waiting ti to come by vacuum).

what you said make 100% sens. but not. 
PWK do work perfectly on 4 stroke and they dont have accelerator pump.
I PERSONALLY DID on my 87 kayasaki bayou, on my honda 250x,
if i knew before that people were so retarded nowadays i wouldnt follow all those ****** "get a phbg and be done with carb problems"buy a phbg put a pwk that the info is all over.
so i'm stuck with many cv carb and none working decently, and a phbg that works like ive never had any carb work this good, but with this issue. but i know they CAN work on 4t just like pwk, i just need to know what it need. 

[aeroxbud]

If it works best with the needle clip at the bottom. Then it sounds like it needs a thicker needle.
Just buying one will be a crap shoot though. That's why you usually buy a set.

[sckanksta]

As a start I would recommend:
40 pilot jet
W7 needle, clip in the second from top
Find a main jet from there

I often get a w16 needle with the sports phbg dellorto copies from china, harder to get those right. Which needle do you have in the carb right now?

[br4inl3ss]

Apr 21, 2024 19:26:44 GMT -5 aeroxbud said:

If it works best with the needle clip at the bottom. Then it sounds like it needs a thicker needle.
Just buying one will be a crap shoot though. That's why you usually buy a set.

ok thanks. if its definitivly the needle, ill try to buy a set. i found motoforce and naraku kit, in the same praice range and mostly, AVAILABLE!.

[br4inl3ss]

Apr 22, 2024 6:13:06 GMT -5 sckanksta said:

As a start I would recommend:
40 pilot jet
W7 needle, clip in the second from top
Find a main jet from there

I often get a w16 needle with the sports phbg dellorto copies from china, harder to get those right. Which needle do you have in the carb right now?

ok thanks.
40 pilot jet is impossible. the screw all the way in its still way too rich it barely stays running.
i MUST use 30 32 or 34. smaller = better (less turns IN). bigger than 36 = screw fully seated and too rich.
does the needle affect in any way the required pilot jet ?
ill try to buy a needle kit. so ill have all of them.
i just hope i wont buy that for nothing because its not the issue.

its legit Dellorto with stock everything but pilot/main jet. that means it has w9 needle.
this is the description of it and its what came on, i verified.
DELLORTO PHBG 19 DS
Main jet : 75
Pilot jet : 45
Choke jet : 60
Needle W9
Diffuser : AN 262 (four stroke)
Dellorto Reference : 2631

maybe the air passage is clogged thats why it needs such small pilot jet and the choke is way too rich ? bit it was brand new liek that so tis unlikely.
or a bad batch that have bad passages ?

[sckanksta]

Apr 22, 2024 10:17:40 GMT -5 br4inl3ss said:

Apr 22, 2024 6:13:06 GMT -5 sckanksta said:

As a start I would recommend:
40 pilot jet
W7 needle, clip in the second from top
Find a main jet from there

I often get a w16 needle with the sports phbg dellorto copies from china, harder to get those right. Which needle do you have in the carb right now?

ok thanks.
40 pilot jet is impossible. the screw all the way in its still way too rich it barely stays running.
i MUST use 30 32 or 34. smaller = better (less turns IN). bigger than 36 = screw fully seated and too rich.
does the needle affect in any way the required pilot jet ?
ill try to buy a needle kit. so ill have all of them.
i just hope i wont buy that for nothing because its not the issue.

its legit Dellorto with stock everything but pilot/main jet. that means it has w9 needle.
this is the description of it and its what came on, i verified.
DELLORTO PHBG 19 DS
Main jet : 75
Pilot jet : 45
Choke jet : 60
Needle W9
Diffuser : AN 262 (four stroke)
Dellorto Reference : 2631

maybe the air passage is clogged thats why it needs such small pilot jet and the choke is way too rich ? bit it was brand new liek that so tis unlikely.
or a bad batch that have bad passages ?

Yep, the needle will also affect the start/idle. Last time I misplaced the e-clip and the engine wouldn't start, was too lean.

Just use the 45 pilot and a more normal size main jet, 2nd or 3rd notch on the needle. Oh, and don't let the needle names fool you; w7 isn't very close to w8 and w8 aren't again behaving so close to w9. Its no logical cronologic naming to it.

Get some start gas too see if that can help you find what's wrong, and check if the throttle cable are ok. Take of the airbox and see inside the carburator when you use the throttle, does it go all the way up/down.

Hope you can find out what's wrong =)

[br4inl3ss]

Apr 22, 2024 16:38:14 GMT -5 sckanksta said:

Apr 22, 2024 10:17:40 GMT -5 br4inl3ss said:

ok thanks.
40 pilot jet is impossible. the screw all the way in its still way too rich it barely stays running.
i MUST use 30 32 or 34. smaller = better (less turns IN). bigger than 36 = screw fully seated and too rich.
does the needle affect in any way the required pilot jet ?
ill try to buy a needle kit. so ill have all of them.
i just hope i wont buy that for nothing because its not the issue.

its legit Dellorto with stock everything but pilot/main jet. that means it has w9 needle.
this is the description of it and its what came on, i verified.
DELLORTO PHBG 19 DS
Main jet : 75
Pilot jet : 45
Choke jet : 60
Needle W9
Diffuser : AN 262 (four stroke)
Dellorto Reference : 2631

maybe the air passage is clogged thats why it needs such small pilot jet and the choke is way too rich ? bit it was brand new liek that so tis unlikely.
or a bad batch that have bad passages ?

Yep, the needle will also affect the start/idle. Last time I misplaced the e-clip and the engine wouldn't start, was too lean.

Just use the 45 pilot and a more normal size main jet, 2nd or 3rd notch on the needle. Oh, and don't let the needle names fool you; w7 isn't very close to w8 and w8 aren't again behaving so close to w9. Its no logical cronologic naming to it.

Get some start gas too see if that can help you find what's wrong, and check if the throttle cable are ok. Take of the airbox and see inside the carburator when you use the throttle, does it go all the way up/down.

Hope you can find out what's wrong =)

ok thank you.
ill ahve to wait a week or two before i get a pack of needles.
meanwhile ill just try with a spacer that mimic another step on the needle.
i will also verify that nothing is clogged (air passage mostly).

i have another issue for sure. too rich on idle and on choke but too lean on acceleration ?... yeah...