dellorto phbg 19mm carb from treatland tuning woes

graydog8josh

New Member
Nov 23, 2012
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Starkville,MS
I got the phbg 19mm carb from treat and I have no idea how to start tuning it.
it says its got a starter jet
an idle jet and a main jet, needles atomizer and all this just to tune it.

All i have that will fit it now is the main jets 60 to 85

to get a roundabout even tune comparable to my rt carb that i have on there right now with a 66 jet what should i do.

Btw im running 36:1 with a mildly ported reeded and tuned motor it runs just okay with the 66 jet and the rt carb (34mph) but it was running super rough when i slapped on the new carb and i couldnt get a good idea of what was happening.
 

graydog8josh

New Member
Nov 23, 2012
447
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Starkville,MS
Really what im looking for is some to tell me
" hey im at sea level, i have a reeded motor with an expansion chamber. I have the phbg carb and i am using..
main jet: xx size
idle jet xx size
needle : xx
clip position: xx
atomizer: xx
 

Goat Herder

Gutter Rider
Apr 28, 2008
6,248
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N.M.
60 to 85 is way too lean for me over here at 6000 ft. On the little Morini I beleive 90 or 92? Pretty sure about that... With the stock atomizer of course and idle jet.. not too sure? 50 to 55 would be my guess for idle jet size. Been a long time since I had to give my carby some thought. We have folks here at sea level. Supprised nobody has piped in?
 

Goat Herder

Gutter Rider
Apr 28, 2008
6,248
10
38
N.M.
I think mine came stock with a 262 AU atomizer because I had to go three atomizers sizes the other direction on mine, and know it was a W9 needle. I run a 49cc two stroke Morini. If that helps?
 
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Huffydavidson

STREETRACER/MANUFACTURER
Jan 29, 2012
1,076
4
38
st.louis,mo.
I have two PHBG carbys ones a 19.5 and the others 21mm and DUDE your back in class . There is so many variants is not just altitude and atmosphere but how your engine setup is configured.
So I'm pretty good at it now, however it has taken quite some time to get to the point of fine tuning. So if you want to drop me an email and maybe swap phone numbers I'll share with you what I've got I've got several internet pages that I could forward to you and things like that and help you the best I can but it's just too much to do here.
 
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graydog8josh

New Member
Nov 23, 2012
447
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Starkville,MS
right now im at 74 main
40 idle
clip at bottom
and it is a little boggy right off idle the middle is pretty good and full is boggy at hi rpm it is boggy too
 

rogergendron1

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Sep 18, 2013
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The dellorto phbg is sweet but a newbs nightmare lol

You can get idle jets idle jet emusion tubes main jets and main jet emusion tubes new needles with differant tappers and even differant cutaways for the slide! !!

Now the stock emusion tube for the main is probably good and the idle jet is probably good too and the needle is probably the right tapper and your slide cutaway will worl just fine

so that leaves us with the idle jet and the main jet amd slide needle posistion


i like to mark on the throttle an arrow then on the pther side i mark wot then i mark closed then half way then 1/4 then 3/4 throttle position on the twist throttle . This way when i look down i can see an arrow pointing to a marker and the marker would indicate the jet the carb is on at that throttle posistion . Exe i twist the thrpttel and take off then it starts to bog so i look down and i see the arrow pointing just over the half way mark . That would let me know i am on the needle jet and its position or shape need to be changed! !!
 

rogergendron1

New Member
Sep 18, 2013
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woburn ma
Or or i get a bit of four stroking and look down to see i am pointing at the 3/4 marker dead on . That would tell me the main jet is too big and the needle should go down one clip

you realy need some markings on your throttle to see the jets and to tune them during test rides!

but put it this way if the bike even starts with the carb on it then your close already!
 

graydog8josh

New Member
Nov 23, 2012
447
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Starkville,MS
Thanks roger i think important too rich at full throttle but instead of sputtering its diving likeits getting no fuel its weird. would it do that if it was 6 sizes too big it was doing it at 82 and its still doing it at 74
 

graydog8josh

New Member
Nov 23, 2012
447
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Starkville,MS
just so people can believe ive spent time and money on jetting, lol. heres some of my jets, they're all over the house.

jets from 60's
5 stock jets(im guessing their all 70 jets i never use nt stock jetting unless its on a new engine with the nt carb completely unmodified and breaking in)
70's 72 74 76 77
and an 80 and 84 jet

also , plugs. i have never used the stock ones but i collect them when i sell people good ngk plugs to run their bike on
 

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ldrancer

New Member
Jun 3, 2014
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3rd planet
hold it full throttle for a bit. and see where its at. sometimes it would take me nearly 2 miles of riding around to see what its doing. maybe your 3/4 is too rich. if its boggy at around 1/4 throttle, when you get going, then your rich. if at takeoff, as you rip the throttle back the bike doesnt even move in the yard. pilot. mixture screw. or maybe the atomizer.
 

Huffydavidson

STREETRACER/MANUFACTURER
Jan 29, 2012
1,076
4
38
st.louis,mo.
Moped Army has some real good info on tuning the PHBG carbys. Also do a Google you'll be reading and learning a lot!!! They are COUNTLESS ways to get the same resuits!!!!
 
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graydog8josh

New Member
Nov 23, 2012
447
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Starkville,MS
yeah thanks hd. thats what im trying to use to tune by and this is where im at:

top speed 36mph

idle jet 40
main jet 85
needle in richest setting
idle mixture screw halfway in/out

about the same top speed as my rt carb :-\ with less responsiveness and much bigger jets. the 70's jets were way too lean at wot it was cutting out
 

ldrancer

New Member
Jun 3, 2014
11
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3rd planet
i figured that stuff out on my own. they wont really help, .. unless you got a moped. i would think a bike wth a motor on its a moped.

but for me to find any problems with up top tuning, i had to cruise my bike, well, floor it with it just running badly, on me, for 2 miles. at least. i have a cht gauge also. the worse part is when its actually running if its running hot. if its not hitting then its usually not raising temperatures either. unless you got an air hole, leak, or something too. going on. after 2 miles or so, a needle problem, would usually disappear then the main jet would run for me showing how its tuned. usually every main jet will hit, but unless their extremely rich. or lean, maybe. yea. but that was my trick to getting the main jet to come u and show up whats going on.

im not remembering how i figured where the main jet was or the needle was in this place now, thou. and by the way oh who cares about that other place. im giving tips right here.

hes at a forum why you gotta mention another one.
 

Huffydavidson

STREETRACER/MANUFACTURER
Jan 29, 2012
1,076
4
38
st.louis,mo.
I changed slides up from 30 to a 40 in one bike and 50 in the other BIG difference in throttle response. Gona order a 60 just to have in my "tuning drawer"
 

ldrancer

New Member
Jun 3, 2014
11
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3rd planet
cutting out? probably rich. keep on holding it. you mean, raw dogged cutting and running pretty erratically and hesitatingly, like? thats lean. but, just boooorrrr is rich. if you hold it itll usually for me, pop and backfire. holding it wide open. edit: then you'll know its rich.
 
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