21mm PHBG tuning.

Patrick Kearns /

Hey im running a 21 PHBG carb on my 78 free spirit.

setup

70cc Kstar

case matched E50

19mm intake

tecno boss pipe

malossi E12 air filter

CDI

timing 17 degrees

main jet 88

idle jet 45

So at WOT it boggs down but if i back up on the throttle alittle it stops bogging and will run fine. did a plug chop. how does the color look? still in the break in period.

plug.jpg

Re: 21mm PHBG tuning.

#CrazyWayne™ rocks. #CrazyWayne /

Death plug

Re: 21mm PHBG tuning.

hey hey, its wayned world!

Re: 21mm PHBG tuning.

Looks like a melted piston

Re: 21mm PHBG tuning.

Patrick Kearns /

What should I up jet too?

Re: 21mm PHBG tuning.

which atomizer and needle are you using?

Re: 21mm PHBG tuning.

#CrazyWayne™ rocks. #CrazyWayne /

What oil and mix you running in this thermal reactor?

(edited)

Re: 21mm PHBG tuning.

Overpriced Parts /

Just bing it (14-15mm will be great) and save your phbg set up then after your tuning skills are better then reinstall.

That way your kit will broken in not broke.

You need to enjoy your moped when the weather is nice

Re: 21mm PHBG tuning.

You need to give way more info bro. or pictures. might be the airbox/filter your using. i say buy a nice 83-86 jet range and some saber fuel 100:1 off treats.

Re: 21mm PHBG tuning.

what plug is that? try a colder one. i run a b7 in my 70cc with a 21mm phbg.

Re: 21mm PHBG tuning.

Im running a 86main on a 21phbg and my plug looks no where near the same color as that. Kabooom is in your near future if you don't fix that

Re: 21mm PHBG tuning.

DON'T bing it... fix the tuning before you ride anymore.... Bings are for stock bikes - they have no idle mixture circuit. You can run them on kits, but I don't know why you would.

Put bigger jets in it till it four strokes, then back down until stops.

I hate bings. 88 is close... Buy some 90's. You shouldn't need to break 100... If you do I bet you've got a leak... Have you leak checked it? 88 is reasonable for that setup I think - my money is on leaks.

If you used the stock gaskets I bet that's your problem.... They're so thin they're worthless. Cut some real gaskets. You always have to trim gaskets, so skip a step and cut your own.

Re: 21mm PHBG tuning.

Overpriced Parts /

Wrong ^^ its the pipe that makes the power . 56mph with my polini maxi 15 mm bing derestricted Estroil no porting.

I hit 60 mph with rev run pipe 15 mm bing

21 mm is a waste on a 70 cc anyway even if tuned unless it's ported

The inside of the intake port is = to about 18.4mm

So a 19mm carb is fine

I run 19-21 phbgs

And mikuni 24mm carbs too

so I'm not stupid

I ran a 19mm dellorto on a dmp 70 cc and it was fine

It was a little faster and had more mid to hi rpm power then a 14-15 mm bing

but not double and a 14 mm bing with rich needle just killed it off the line .

Each to his own I'm tired of emails of how to jet/tune on a 70 cc kit with a phbg and local kids wanting me to fix tune their treats "party pack combo".

It's just easier and cheeper to get a bing and 3 jets (14mm 70,72,74 ), ( 15mm bing #78, 80, 82 jets)

Then a 21 mm phbg and 10-15 main jets, 3-4 pilot jets, 2-3 slides (though# works good for me) 2-3 needles ( though # 8 seemed to work good for me)

Re: 21mm PHBG tuning.

#CrazyWayne™ rocks. #CrazyWayne /

That's right Ken hell good tuners can go 50+ with a 12mm carb.

And all you need to do to adjust the bing idle mixture circuit is mod the slide to lean it out.

Running a 21mm carb without doing major porting with a real intake an pipe not a POS boss pipe slapped on a non-ported kit.

That big carb is for spinning 12+K in the hands of a pro tuner to go 70mph.

Hell i nip 70mph with a 19mm carb @11.3k the power is in matching your porting to the pipes hit, then you tweak the back presser to the carbs flo.

Bing info

https://www.mopedarmy.com/forums/read.php?7,2891329,2893812

https://www.mopedarmy.com/forums/read.php?7,2116363

https://www.mopedarmy.com/forums/read.php?7,2117054,2120556#msg-2120556 (edited)

Re: 21mm PHBG tuning.

Chill Ken - don't spaz out. I never said the carb made the power. I realize that the 21mm carb is over kill for this bike... I know people go really fast with tiny carbs and people hardly ever max out the potential of their carb throat diameter

I don't like bings because they're one jet carbs... hell, get a 15mm phbg or Amal... SOMETHING with an idle mixture circuit. I just hate 14sha's and bings. I don't feel like they have very well tuned mid-low ranges on kits. If you're only going WOT - go for it - for those of us that commute this isn't the case.

I never would've bought a 21mm carb, but if I had a 21mm PHBG and a bing and I had to put one of them on a kitted engine - I'd always put the 21PHBG on.

Bings are fine if you're at WOT all the time, but for those of us that ride in cities and congested areas - it's just not ok. The low and midrange needs to be tuned too so we're not cooking our cylinders doing 25-30, not just WOT.

Have you ever watched a temp gauge on a kitted engine when you come to midrange and low speed with a Bing? I have. That's why I don't run them on kitted bikes.

Re: 21mm PHBG tuning.

I agree with ryan there, bings are just too limited , you can adjust your entire range with a phbg

Re: 21mm PHBG tuning.

#CrazyWayne™ rocks. #CrazyWayne /

The bing's tuning is not limited just your ability to tune Mel.

Re: 21mm PHBG tuning.

Overpriced Parts /

I'm chilled Ryan I'm not yelling in bold type ha ha

But your mistaken again my bing powered bikes are some of the coolest bikes I got and I run full side covers. In you few years of moped experience you come to only one conclusion . I gots several bikes running different carbs it's no biggie for me this moped tuning stuff is easy compared to banks of carbs on multi cylinder motorcycles that I had to tune. So that being said bings a better choice for noobs running unported kits and the cheep aftermarket pipes.

Most of the people who seize on this forum are with non bing carbs anyway

I like difference of opinion and nothing is set in stone .

I'm not hating so don't either

Re: 21mm PHBG tuning.

I'm not yelling... Bold face is for emphasis, CAPS LOCK IS FOR YELLING haha

Just wanted to make sure I didn't have words put in my mouth again like saying the carb makes the power...

I'm sure your bikes run perfectly cool in the upper throttle ranges - I have no doubt and will not dispute. However, I refuse to believe you can run a bing at low throttle speeds and idle with proper mixture on kitted engines. That's where my problem lies.

Since it's been so long since you've been a newb, I don't really think you're qualified to ascertain what is good newb advice and what isn't. I on the other hand, still know less that you and wayne, but know enough and have been a newb recent enough to know that someone in this position would be better off with PHBG (once again IMO).

I don't see what the problem with PHBG's and the kids around your area is... work your way up slide positions from idle and stop when you get to WOT... I'd tell em to buzz off and try harder. It's not that hard. Don't see how people don't get that.

Not trying to be an ass, just trying to save this guy some headache because I believe the bing is going to give him MORE trouble.

If patrick is still reading here's the link to the dellorto tuning manual (edited)

Re: 21mm PHBG tuning.

Also, the reason I'm being so passionate is because I remember when I switched my bing out for a Phbg on my 70 kit... I was so much happier and it made so much more sense.

So it is just my difference of opinion... Lots of frustrating hours of opinion tryig to get that damn bing to run right

Re: 21mm PHBG tuning.

@Wayne.. you may be right about my ability, and I highly respect your experience and knowledge on the subject, but I don't see how a bing can be as tunable as a phbg considering it's lack of options available. So fill us in Wayne, instead of just acting smart ass.

Re: 21mm PHBG tuning.

#CrazyWayne™ rocks. #CrazyWayne /

^ true bings can be a bitch till you find the right combo of parts to make it perrrrr & rip.

Tuning a 21mm phbg will be harder for a nub with good skills.

If he had a 17.5mm to 19.5mm max Ya it will be much ezer to tune in.

the flow from his 68cc kit with a 21mm carb will be confusing to tune in and change with any whether and temp change.

Re: 21mm PHBG tuning.

#CrazyWayne™ rocks. #CrazyWayne /

@ Mel we covered the bing tuning do a search and read the links i posted.

Re: 21mm PHBG tuning.

Crazy, Thanks, I will ,and understand ,I'm not near the tuner you are, Wayne, but that's why I come here, I want to know what you know. And treats has only, 1 needle, 1slide, and 2 atomizers to choose from, if there's more available , I'd like to know where.

Re: 21mm PHBG tuning.

Overpriced Parts /

No harm Ryan. Man bings are sooo easy and are great carbs especially the large 17-40 mm sizes. Mat from motorwest says bings are the best for his race motorcycles " so crisp and clean carburation better then mikuni, dellorto, keihin carbs"

If after a bing is jetted correctly for good power all around but it won't idle then a small about 3/32 ish hole in the front and rear of the slide is all I ever needed to get a good idle and that is with a full rich needle clip sometimes. I'll post a picture of the slide hole sometime soon.

I think a 17mm bing works better then a 19-21 mm on a kstar-dmp 70cc kit.

I ran 2 -14mm bings on a 60cc euro kit it ripped and I had it tuned in a afternoon but a pain with cables, hoses ,space and plain looked stupid too.

I even used a lawn mower carb on a kit before.

Run what you brung ha ha.

No wrong way is what I say. Experiment have fun

Re: 21mm PHBG tuning.

There are posts about modifying the slides and drilling an aux hole in the body near the floor. I fiddled around with it quite a bit with no luck. Maybe I'll revisit it someday just for entertainment, but I probably won't fool with it again.

Re: 21mm PHBG tuning.

Overpriced Parts /

Ah not on the floor of the slide much higher that is the secret of unlocking the bings power and having good idle

Re: 21mm PHBG tuning.

Overpriced Parts /

That back hole is in about the same spot (the highest spot on the slide at idle) too.

When the throttle is cracked the hole is covered not affecting/changing the flow or design of the slide

A groove or "eyebrow"and or positioning the spring out of the way on the inside of the slide may be needed for more air flow but maybe not.

photo(175).JPG

Re: 21mm PHBG tuning.

#CrazyWayne™ rocks. #CrazyWayne /

Ken your back hole mod is just an air leak, it dose not mix air with gas & oil and can give lean pockets in the combustion burn.

This slide mod will lean the idle mix.

Stock slide on left------------- slide with mod on right

(edited)

Re: 21mm PHBG tuning.

Overpriced Parts /

Nope. Only leaks air at idle not anywhere else. As soon as the throttle is cracked the holes are blocked but has to be in the right place or yes you will have a air leak.

Many times the slide profile needs to be stock not modified.

If modded like what you show you still may need to put a hole

I do need to show more pictures and how to make placement

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