dellorto PHBG 21 mm carb setup

good luck to you, take your time with it don't rush things, it takes time to develop a sense & feel for tuning 2strokes, it's both science & art.

i agree i am doin it today if my idle jets arive so hopefuly it will work and i will be thankfull to you because its you that has given me great advice 9||69||6 my denso 27 spark plugs looks to be long threaded and my old one was short i hope it fits:) cost me £15 haha .
 
:'(just fryed me engine. cut dead today while doing 63 mph maybe size 80 jets to lean looks like its going to be expensive. no compresion at all. OUCH!!!!!!!!
 
WTH happened? did you stick a jet a lot smaller than your previous one? also did you bleed off the cooling system of air bubbles or pockets thoroughly? the cooling system palys a big parts in keeping your cylinder from seizing.

if you holed a piston which i suspect you have a preignition problem which can only be solved by increasing your cooling capacity (2 radiators).
 
WTH happened? did you stick a jet a lot smaller than your previous one? also did you bleed off the cooling system of air bubbles or pockets thoroughly? the cooling system palys a big parts in keeping your cylinder from seizing.

if you holed a piston which i suspect you have a preignition problem which can only be solved by increasing your cooling capacity (2 radiators).

I took it apart i had a water leek out of the bleeding nipple,
i rid thirdteen miles through traffic at an average speed of 30-40 mph then opened it up to see what it could do then i reached 63.2 mph on my gps then engine cud dead .
inlet manifold vibrated lose,
my piston ring was ring inside its grove on the side of the piston were the arrow is, nearest floor or bottom,
my barrel has marks on it and it makes a horrible screetching noise when you turn it over slowly which i think it might be the ring vibrating since the ring grove had enlarged.
my piston is recked how do i upload photos on here and i will show you. my spark plug was white,
dry and i suspect it was far to lean because it was screaming the revs just kept on going and going.
 
go to imageshack.us, click browse to choose pics from your file, you can also resize them by checking the box & setting the pic size, click upload or host it button, when the next page appears scroll down the page & copy "the hotlink to forums 1" & paste it here, voila the pics are posted.

that does indeed suck, probably the manifold is teh culprit which was aggravated by the coolant leak on the nipple. as a great 2stroke tuner once said "90% of my work is spent finding out what doesn't work so i can succeed in the remaining 10%."

live & learn from your mistakes, 2stroke tuning is never easy.
 
an old man told me today "a person who desent make mistakes, doesnt make anything at all! i just need to thread lock my manifold bolts. also i took my cylinder to a machanic and he said the cylinder is fine just needs polishing or buffing. also my piston is wrecked the piston ring doesnt fit into its grove i will order a new one tomorrow. also i think i need a better bleeding nipple on top of cylinder because the one i have has a whole in it do you know anything i could replace it with ? also i would like to get a more flow pump any sugestions please.
thank you for your help.

my idle jets size 40, 42, 45 came today so it is just the case of building the bike back up but this time much better and stronger.9||6
 
just concentrate on building it right this time, save the porting for later until you tune it to run reliably.

did you measure your squish last time? this time set it to 0,60mm just to be safe from detonation.

i have never used loctite in all my years of building engines, the key is just to tighten the bolts enough not to strip the threads.
 
What is porting i have been wandering about that for ages. Is it where you grind the port holes bigger? because i read on this that people have been tuning there ports but i dont know what it is. my squish is 0.56mm. most of my faring bolt clips ar threaded of taking them off all the time. i need to get some new ones. i am building it today after work so any tips on how to run the engine in. i hear that you have to take it easy but give it bursts of full throttle to seal the rings. do you know anywere in the uk that sells better water pumps.

Thank you tiba
 
honestly i don't know any stores in the UK so i can't help you with that.

porting is a tuning process which involves altering the port dimensions of the cylinder & crankcase for more performance, this should only be done with someone with a lot of experience & knowledge of 2stroke tuning.

as for break-in we just run the engine at around 6000 revs & play it around there for an hour, after that we consider it broken in. it's from the Malossi manual that came with the MHR BB 77cc kit.
 
i have ran it in for an hour or so now. my oil ratio is 36:1 my idle jet is 45 and my main jet is 85 if i make the main jet any higher it gets worse i cant even pull away with out it going blurrrrrr. after about 40 mph it just takes off. i will keep trying different jetsizes. any ideas? also with jet sizes 45 and 92 wet the plug. i still have a standard clutch with blue springs and dopler reed valves so i am going to buy a polini reed valve tonight and then see if that makes a difference.
 
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are you running with the stock air box on? on our Beta Ark with Evo1 LC untuned it has 50 pilot jet & 72 main jet, we don't have a smaller pilot jet here so i just turned the scew by .5 turn from close.

also the needle clip is set at the top groove (#1 leanest) so it doesn't blubber when you crank the throttle from idle.

try running more oil, 25:1 should be fine.

what are your transmission settings? sounds like the tranny is off if it takes you 40mph before it pulls strong.
 
are you running with the stock air box on? on our Beta Ark with Evo1 LC untuned it has 50 pilot jet & 72 main jet, we don't have a smaller pilot jet here so i just turned the scew by .5 turn from close.

also the needle clip is set at the top groove (#1 leanest) so it doesn't blubber when you crank the throttle from idle.

try running more oil, 25:1 should be fine.

what are your transmission settings? sounds like the tranny is off if it takes you 40mph before it pulls strong.

is seems to run best with 50 idle and 80 main. i didnt know you could adjust the needle clip. if i take it apart do you think i will be able to adgust it (phbg 21mm).

my oil is 35:1

my transmition settings are: polini super speed variator (9 rolers). i got lightest waights that came with is installed. and blue clutch springs.

i want to upgrade all my transmitions but i dont know which stuff to get appart from the polini evolution 2 setup.

also my timing is about 10 mm advanced and my overheating light keeps coming on until the power kicks in at 40- 45 mph.

Thank you very much tiba !;)
 
:'(just fryed me engine. cut dead today while doing 63 mph maybe size 80 jets to lean looks like its going to be expensive. no compresion at all. OUCH!!!!!!!!
How's the new engine? Done yet? Sorry about the motor bud.

I'm still in testing, currently at 96 main 42 idle. (I'm going to lean to a 94 today)
It's running good, but still too rich. Plug blackens at 1/2 to FULL throttle.

Here's something, The bike has always run smooth at WOT, (by smooth I mean vibration-free, clean-sounding burn, massive pull), but that's where it is still running the richest and blackening the plug. Then, at low rpm, it is just right, (i think) on which jet (42), but doesn't run as smooth as WOT IMO.
Maybe Tiba could share what he knows about this. I assume it is related to my taller gears as the bike tries to get moving.

I washed the bell and the clutch pads, and there is still a hint of vibe at low end, but it's much better, and haven't stiffened the clutch yet but will play with that next. What would happen if you loosened your clutch way down towards like 4000rpm? Is that more like a stunt-bikers setup? or, Would it lug and bog up to high rpm? Just curious as I am new to clutch settings, but do get much of the theory.
 
It's running good, but still too rich. Plug blackens at 1/2 to FULL throttle.

Question for ya Tiba. Will a correctly jetted carb bring a dark plug back to a chocolatey brown over time? I ask because I have a few black plugs around now and was thinking that they could be used again when the jetting is right. I know this sounds pretty newbish, but that's because I'm a Newbie. LOL
 
is seems to run best with 50 idle and 80 main. i didnt know you could adjust the needle clip. if i take it apart do you think i will be able to adgust it (phbg 21mm).

my oil is 35:1

my transmition settings are: polini super speed variator (9 rolers). i got lightest waights that came with is installed. and blue clutch springs.

i want to upgrade all my transmitions but i dont know which stuff to get appart from the polini evolution 2 setup.

also my timing is about 10 mm advanced and my overheating light keeps coming on until the power kicks in at 40- 45 mph.

Thank you very much tiba !;)

yes you can adjust the needle clip to richen or lean the 1/4 to 1/2 throttle range, the pilot jet & screw deals with idle to 1/8 throttle range.

are you running the 128mm overrange rear pulley right now? at what rpm the clutch does start to engage?

for the setup that you run you might want to add an extra radiator or install 2 of those flow coolers.
 
How's the new engine? Done yet? Sorry about the motor bud.

I'm still in testing, currently at 96 main 42 idle. (I'm going to lean to a 94 today)
It's running good, but still too rich. Plug blackens at 1/2 to FULL throttle.

Here's something, The bike has always run smooth at WOT, (by smooth I mean vibration-free, clean-sounding burn, massive pull), but that's where it is still running the richest and blackening the plug. Then, at low rpm, it is just right, (i think) on which jet (42), but doesn't run as smooth as WOT IMO.
Maybe Tiba could share what he knows about this. I assume it is related to my taller gears as the bike tries to get moving.

I washed the bell and the clutch pads, and there is still a hint of vibe at low end, but it's much better, and haven't stiffened the clutch yet but will play with that next. What would happen if you loosened your clutch way down towards like 4000rpm? Is that more like a stunt-bikers setup? or, Would it lug and bog up to high rpm? Just curious as I am new to clutch settings, but do get much of the theory.

if you adjust the clutch that low it would surely lug & bog until it hits the powerband. adjust it so it engages just a few hundred rpm before the powerband kicks in, for road racing setups we adjust teh clutch a few hundred rpm well into the powerband.

after you make a WOT run hold the carb, if it's cold you're still too rich & the black plug is a dead giveaway, by leaning it out to a brown color it should give you more power & let the engine rev a few hundred rpm higher.

i always shoot for a clean & crisp (rapid) throttle response when i tune the carb, nothing beats a sound of a well tuned 2T engine.
 
Question for ya Tiba. Will a correctly jetted carb bring a dark plug back to a chocolatey brown over time? I ask because I have a few black plugs around now and was thinking that they could be used again when the jetting is right. I know this sounds pretty newbish, but that's because I'm a Newbie. LOL

that's a 10-4 buddy.
 
are you running with the stock air box on? on our Beta Ark with Evo1 LC untuned it has 50 pilot jet & 72 main jet, we don't have a smaller pilot jet here so i just turned the scew by .5 turn from close.

also the needle clip is set at the top groove (#1 leanest) so it doesn't blubber when you crank the throttle from idle.

try running more oil, 25:1 should be fine.

what are your transmission settings? sounds like the tranny is off if it takes you 40mph before it pulls strong.

It was already on top clip but on my evo 2 instructions it says get a 19mm phbg. I got a 21mm phbg. So it says use 98 main jet which i have. A 262 atomiser which i have, size 40-50 idle jet which i have. this is where i think its not working: the carb has a w16 needle and it says use a w3 needle if you look on the dellorto web site w3 needle if fatter by .45mm which will nake run even leaner. with me having a 21mm carb instead of a 19mm carb which this information about needle sizes. do you think i will need the next size up or down from w3 with the carb being 2 mm bigger.

also my reed valve doesnt have that rubber block with a whole through the middle in it since i didnt get one with the doppler one. but when i looked at the polini one it does and you get to types of reed petals i think because one set of reed petals had one colour wrighting on it and the other set had a different colour.

here are some links of different needles and the polini reed valve:
http://www.adrenalin-pedstop.co.uk/p/POLINI-REED-VALVE-FOR-MINARELL-1505.aspx


http://www.thisoldtractor.com/gtben...specifications_for_phbg_carburetors_-w_slides-

i have already ordered reed valve with block in it just not sure what needle to get with it being a 21mm carb instead of a 19mm carb.

thanks tiba your great help!
 
if you run the W3 needle it might go too lean & seize the piston, even a 0,01 to 0,02mm increase in needle thickness will be a dramatic change for such a small carb. i suggest you stick with teh stock needle for now, it worked for us so i think it will work for you, you just need to tune the carb really well.

what problems are you experiencing this time with the carb & engine?

get the VForce 3 reedvalve it's better than the malossi & polini reedvalves, it's what we use on our race scooters.
 
if you run the W3 needle it might go too lean & seize the piston, even a 0,01 to 0,02mm increase in needle thickness will be a dramatic change for such a small carb. i suggest you stick with teh stock needle for now, it worked for us so i think it will work for you, you just need to tune the carb really well.

what problems are you experiencing this time with the carb & engine?

get the VForce 3 reedvalve it's better than the malossi & polini reedvalves, it's what we use on our race scooters.

like i said i have already ordered the polini reed valve but not the needle i tryed the needle at all settings but still no improvement. im starting to think its my transmition or clutch because my clutch bites after a second or two and the revs dont build up and there is no variation sound. what will cleaning my clutch bell do? and how would i get my clutch to kick in when the power band hits. thats what i would love. i will try and find a site that sells inline radiators. thanks tiba.
 
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