Some HeLP On 28mm Keihin PWK Setting

M

molicka molko

Well-Known Member
Hello EveryOne..Im From Singapore..
Im Riding A Gilera Runner 180 SP..
Now Using A Ported Malossi 172 Kit..
With Standard 180 SP Exhaust..
Cant Use A Aftermarket Pipe,It ILLegal HEre,
& If U Are Caught..Its Not Worth Paying It..haha..!!
Anyway Im Using 28mm Keihin PWK..
Everything Is Running WeLL..
Its Runs Even Better,Then My Mikuni TM24..
But I Just Wondering,If You Can Give Me A Better Setting..
Currently The Carburetor Is Using,
MAIN JET (142) - SLOW JET (40) - NEEDLE CLIP (3)
Roller Weight - 12.5G & 14G..Mix Roller..
Also Here In Singapore IS HOT Weather & 300 Meter Above Sea Level..
So Hope Any Of The Setting Tips,Matches My Local Weather Temperature..
Thanx..Have A Nice Day..!!
:)
 
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Not a big help as i run different setups in our bikes, but i´d say you can fit a 45-48 idle jet and it should be crispier when you snap the throttle.
 
what problems are you experiencing from the carb? fueling problems at part, mid or full thottle? LC engines are very finicky about jetting compared to AC engines.
 
tiba_karotsu said:
what problems are you experiencing from the carb? fueling problems at part, mid or full thottle? LC engines are very finicky about jetting compared to AC engines.
Click to expand...

Hi Wats LC Engine & AC Engine..??
Mind Verify It..
Thanx..

Anyway Im Not Sure,My Problem..
I Think Somewher In The Start & Mid Throttle..
Its Like,When I Full Throttle At Start Or Mid
The Engine Would Go High Rev..
But My Bike Is Not Going Full Speed Acceleration With The High Reving Sound..
Means High Rev Sound With Slow Acceleration..

I Try Test Run It..It Run 140km/h
Like I Said,Diz Is My 1st Time Using Diz
Keihin PWK..
For Me Everything IS Better Compare To
My Mikuni TM24..
Keihin Carb Giving Me More Torque..
But Im Just NOT Sure If My Carb Setting Are Rite..
I Mean The AIR/Fuel Mixture..
Im Thinking Of Using A
145(MAIN JET) - 42(SLOW JET)..??????

ANYWAY I UPDATE MY ENGINE SPEC..
-Malossi 172 Kit..
-Malossi Carb Manifold..
-Malossi CDI..
-Malossi Torque Driver & Spring..
-Malossi Delta Clutch..(RED SPRING)
-Malossi Secondary Gear..
-Polini Speed Control..(Roller Weight 12.5g-14g)Mixed Roller..
-Standard CRANK..
-Standard 180 Exhaust..
-Carb Setting 142(MAIN JET) - 38(SLOW JET)

Weather Temp Is Around 25'C - 36'C OR 37'C - 49'C
300M Above Sea Level..
Hope Can Help Me More & To Understand Something....
Thanx..Have A Nice Day..
 
AC = air cooled
LC = liquid (water) cooled

by your description it sounds like you need to increase the weight of your rollers by a few grams, high revs & slow acceleration is a sure sign of too light rollers, use heavier rollers until the acceleration is in sync with engine rpm.

Piaggio 180cc engines are not high revving engines, they make power at lower rpm so you must test heavier rollers.

Mikuni carbs are crap compared to Keihin, i use the very same carb (PWK28 ) you have on 2 of our dragscooters & they are way easier to tune.
 
tiba_karotsu said:
AC = air cooled
LC = liquid (water) cooled

by your description it sounds like you need to increase the weight of your rollers by a few grams, high revs & slow acceleration is a sure sign of too light rollers, use heavier rollers until the acceleration is in sync with engine rpm.

Piaggio 180cc engines are not high revving engines, they make power at lower rpm so you must test heavier rollers.

Mikuni carbs are crap compared to Keihin, i use the very same carb (PWK28 ) you have on 2 of our dragscooters & they are way easier to tune.
Click to expand...

Thanx..
So I Need To Try A Heavier Roller's..
I TRY USING 14g Rollers Before..But It Ends Up Less Torque..
The Power Climb Slowly..
Any Tips What Roller To Try..??
How Bout The Carb Setting..
Should I Try Using 145(MAIN JET)42(SLOW JET)..
Im Now Using A 142(MAIN JET)38(SLOW JET)

Thanx Again..!!
 
ok, try changing out 1 roller at a time & increase it by 1g then test it, only this way you can really fine tune the transmission, don't change out all of the rollers at once, that would be too big.

as for the jets what is the engine response with the 142 when you are at wide open throttle? is it pulling hard? does it sputter? does it bog down like it has run out of fuel?
 
tiba_karotsu said:
ok, try changing out 1 roller at a time & increase it by 1g then test it, only this way you can really fine tune the transmission, don't change out all of the rollers at once, that would be too big.

as for the jets what is the engine response with the 142 when you are at wide open throttle? is it pulling hard? does it sputter? does it bog down like it has run out of fuel?
Click to expand...


Ok Thanx..I Take Note Of The Roller Change..

AS For The 142 Main Jet..
It Doesn't Sputter..
It Doesn't Bog Down..
Not Sure Bout Pulling Hard..
What Do You Really Mean By Pulling Hard..??

Neway Earlier Today..
I Did Some Test Run..
Rollers 12.5g-14g..
With 145 Main Jet - 42 Slow Jet..
Previous It Was 142 Main Jet - 38 Slow Jet..

I Notice That The Engine Doesn't Have The High Reving Sound Problem,With The 12.5g-14g Rollers..
I Mean My Acceration Equal To Reving Sound..
Kind Of Like It..
BUT Power Has Slighter Torque..& Slacking Abit..
Its More Harder To Get Speed After 120Km/h..
I Suspect Of The 42 Slow Jet..
My Bike Feels Like Its Eating To Much Air..
The 145 Main Jet Seems Rite to Me..
Wat DO YOU Tink..??

Anyway Some Question..
What Do We Need To Set First..? ? ?
Set The Rollers OR Carb..? ? ?
Cause Im Experiencing..
When My Rollers Are Light-We Need A Richer Carb Setting..
& When My Rollers Are Heavy-We Need A Leaner Carb Setting..
Is This True..??
Am I Right..??
Or Just My Instinct..HAH..!!
HELP..:'(

Its Really Hard To Set This Keihin PWK On My Runner..
Compare To My Previous Mikuni TM24..
But I Know That Keihin Are Way Powerfull..
Fast Respond..
Cause I Do Own A KTM 200..
With 39mm Keihin PWK..
Wont Give It Up On This 28mm Keihin..
Just Need Some Patience..

Thanx For Ur Time On Me..
Do Help Me More..
Have a Nice Day..!
Cheers..!!!!
 
you change too many things at once, you should concentrate on getting one part of the system running correctly befoe you move on to adjusting another part or you'll get confused as to what has made it work better o worse.

LC engines like leaner mixtures & when you get the main jet size right it will pull hard at wide open throttle, i think you should put the 142 back & test again with the current rollers, if it gets better then try going leaner like a 140 or 138 & try again. you'll know when you have gone too lean on the main jet when you go WOT (wide open throttle) & the engine simply bogs down like it was running out of fuel, if that happens put back the previous main jet & you're done with it.

the pilot jet only deals with idle up to 1/4 throttle position, it doesn't affect WOT position so don't go changing the pilot jet when you want to adjust WOT operation. here is a guide on how to tune a carb;

pilot screw = idle
pilot jet = idle to 1/4 throttle position
needle diameter = 1/4 to 1/2 throttle position
needle taper = 1/2 to 3/4 throttle position
main jet = 3/4 to WOT

on our 70cc & 80cc drag scooters we run 130 main & 38 pilot (70cc), 128 main & 35 pilot (80cc) with the Keihin PWK28 carb, since you have a bigger displacement the engine is sucking harder on the carb so the vacuum signal to the jets will pull more fuel so the need to jet it leaner.

carbs by themselves are not powerful, it is the tuner that makes them powerful by adjusting them to work perfectly for the given engine setup & conditions. a carburator is only as good as the person tuning it, you can buy the best carb in world but if you don't know how to tune it then it is worthless.

goodluck
 
tiba_karotsu said:
you change too many things at once, you should concentrate on getting one part of the system running correctly befoe you move on to adjusting another part or you'll get confused as to what has made it work better o worse.

LC engines like leaner mixtures & when you get the main jet size right it will pull hard at wide open throttle, i think you should put the 142 back & test again with the current rollers, if it gets better then try going leaner like a 140 or 138 & try again. you'll know when you have gone too lean on the main jet when you go WOT (wide open throttle) & the engine simply bogs down like it was running out of fuel, if that happens put back the previous main jet & you're done with it.

the pilot jet only deals with idle up to 1/4 throttle position, it doesn't affect WOT position so don't go changing the pilot jet when you want to adjust WOT operation. here is a guide on how to tune a carb;

pilot screw = idle
pilot jet = idle to 1/4 throttle position
needle diameter = 1/4 to 1/2 throttle position
needle taper = 1/2 to 3/4 throttle position
main jet = 3/4 to WOT

on our 70cc & 80cc drag scooters we run 130 main & 38 pilot (70cc), 128 main & 35 pilot (80cc) with the Keihin PWK28 carb, since you have a bigger displacement the engine is sucking harder on the carb so the vacuum signal to the jets will pull more fuel so the need to jet it leaner.

carbs by themselves are not powerful, it is the tuner that makes them powerful by adjusting them to work perfectly for the given engine setup & conditions. a carburator is only as good as the person tuning it, you can buy the best carb in world but if you don't know how to tune it then it is worthless.

goodluck
Click to expand...


Thanx Again..
Now I Understand..
I Do My Best Fine Tuning It..
Anyway Wher U R From..??
 
@ tiba
Your'e running @ 130 main jet on your 70cc there?
The temp over there must be the difference.
In holland we usually dont go lower then 135.
 
tiba_karotsu said:
close, very close my Singaporean neighbor. ;)
Click to expand...


Close Huh..!
Can It Be Malaysia OR Indonesia..??
Really Wher U From..??
HAHA..!!
Anyway,I Oready Get My Bike Perform Better..
Im Using A 140(Main Jet) 38(Slow Jet)..
Someday Wana Try Lean It To 138..
All Thanx To You..*D
Thanx For Ur Very Patience..
Now I Understand More On Keihin Carb..

& Oso Can I Have Some SparkPlug Tips..
Im Now Using The Denso Iridium IW27..
Tinking Of Using A Colder Plug IW29..
Can Share PRO'S & CON'S Between This 2 Sparkplug..??
Does It Affect My Carb Setting..??

Thanx..!!
 

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