Pulling my hair out over PHBG tuning

Hey guys, I'm a little stumped with my current setup and am trying to finally figure out why it isn't running its best. Here's the breakdown:

-19mm PHBG race style carb on an AV10 50cc Doppler setup w/Doppler pipe and Polini reed cage

-86 main jet

-42 pilot jet

-Stock starter jet

-W7 needle set on highest notch (leanest setting) (I've tried it on the second highest notch and also tried a W9 needle on the top 2 notches with little change)

- AU 262 atomizer

-Stock 30 slide

-Treats 12v CDI with a Jog box set at 1.5mm (it retards ~.5mm at ~8000rpm iirc)

-B7HS spark plug

With this setup it barely revs out on the stand and when you're riding it it seemingly 4-strokes like crazy pretty much everywhere from just off idle until WOT unless it gets on the pipe, then it seems to clear out and run smooth-ish on the upper needle up to WOT. I've changed the pilot from a 45 to the 42 and have been dropping the main down to where I'm at now but it seems to only have a little effect and it's already on the small side. My temps are around mid/high 200s idling and gets up to around 380 within a couple of miles of full throttle blasting. Based on the tuning spreadsheet I'm a little nervous to go much leaner but I don't know what to do at this point. From what it looks like my options are to maybe drop the pilot to a 40, use a #40 slide and maybe raise the needle a notch to compensate a bit?

TIA

Re: Pulling my hair out over PHBG tuning

If you have a 48 main try that or the 45 with the needle in the middle setting. Try the w9 first.

Re: Pulling my hair out over PHBG tuning

Sounds like maybe other issues.

Any leaks?

Re: Pulling my hair out over PHBG tuning

Reeds too soft?

Re: Pulling my hair out over PHBG tuning

It's your timing I realized.

1.5 is way too low for a jog box.

Re: Pulling my hair out over PHBG tuning

Swap the 2 stroke bushing in?

Re: Pulling my hair out over PHBG tuning

> JBOT Admin Wrote:

> -------------------------------------------------------

> It's your timing I realized.

>

> 1.5 is way too low for a jog box.

yep, set your main back to a good known value or you'll smear it for sure, watch your CHT and start bringing that timing up around 1.8. The engine is damn near running backwards by the time it retards.

Re: Pulling my hair out over PHBG tuning

Alright, I'll reset my base timing to 1.8mm btdc tonight. In addition to upping the main should I do anything else? (edited)

Re: Pulling my hair out over PHBG tuning

Been there done it.

chuck the PHBG in the trash, its going cost you loads in bits and still not work.

wasted 2 whole summers missing around on phbgs on my za50, i got even worst when i spent a load on race cdi, solid state. I

buy a mikuni done in half hour mate.

Re: Pulling my hair out over PHBG tuning

If you running reeds, drop the AU 262 atomizer its never going work, run the 4 stroke one.

Re: Pulling my hair out over PHBG tuning

Lol if you can't tune a phbg you dumb as fuck.

However, overly retarded timing will cause any carb to be un-tunable

Re: Pulling my hair out over PHBG tuning

Yea phbg are super easy to tune. Mikuni are just more forgiving and will run half way decent out of tune.

Re: Pulling my hair out over PHBG tuning

> Jason Ford Wrote:

> -------------------------------------------------------

> I cant figure out how to tune a PHBG

> Jason Ford Wrote:

> -------------------------------------------------------

>Get rid of the AU262 bushing

solid advice right there...

Re: Pulling my hair out over PHBG tuning

Once you start to get a handle on the set up STOP ADJUSTING EVERYTHING AT ONCE, index the throttle to 1/8, 1/4, 3/4 and tune to the sections of the index as pilot, atomizer, needle, main. Less chance to become lost.

Re: Pulling my hair out over PHBG tuning

> Graham Motzing Wrote:

> -------------------------------------------------------

> > Jason Ford Wrote:

>

> > -------------------------------------------------------

>

> > I cant figure out how to tune a PHBG

>

> > Jason Ford Wrote:

>

> > -------------------------------------------------------

>

> >Get rid of the AU262 bushing

>

> solid advice right there...

Is that a joke? I thought the AUs work well in reed setups, at least as good as an AN?

Re: Pulling my hair out over PHBG tuning

So, based off of some others opinions it seems like I wasn't running enough advance so I re-timed it to 22° (1.8mm btdc), changed out the plug (it was black) and upjetted to a 92. It's a bit revvier in the low end but still 4-strokes throughout the range and bogs out at WOT (sounds different though, lean bog now), it can't even rev up enough to variate. I messed with the mixture screw and it seems to marginally wake up the bottom end when it's only about half a turn out from fully in. At this point I think I'm going to drop to a 40 pilot, hopefully that cleans up the low throttle position fueling enough to run it into the needle without 4-stroking. Other than that (and upping the main a bit more) I'm still at a loss. Maybe a 40 slide would make a tangible difference?

Re: Pulling my hair out over PHBG tuning

is it one of those doppler pipes with a crazy restrictor in it? I dunno if they still do that but they used to be hella restricted for the euro market

yeah i was just joking that dude said he couldn't figure out how to tune a phbg then proceeded to give you bad tuning advice.

AU atomizer should be perfecto.

Re: Pulling my hair out over PHBG tuning

I only saw the restrictor in the ball joint ( removed it) but not the pipe itself. Is there one in the pipe too? My bike was going pretty fast before I dropped in the W7 so I don't think there's an obstruction there...

Re: Pulling my hair out over PHBG tuning

Mikey Antonakakis /

Should just be in the ball joint.

One tough part with a good 50cc kit and pipe (like you've got) is that the fueling requirements are vastly different from low to high rpm, much moreso than most moped kits. Gets worse when you port. Also not helped by the low compression ratio (at least for the water cooled kits) you get out of the box. My Peugeot Doppler kit was like 2mm squish out of the box? (And still is). It absolutely rips at high RPM but can hardly rev into the powerband. Best to just tune clutch and variator for high RPM use only, IMO. At least if you're okay screaming everywhere you go.

Re: Pulling my hair out over PHBG tuning

> Jason Ford Wrote:

> -------------------------------------------------------

> Been there done it.

>

> chuck the PHBG in the trash, its going cost you loads in bits and

> still not work.

>

> wasted 2 whole summers missing around on phbgs on my za50, i got even

> worst when i spent a load on race cdi, solid state. I

>

> buy a mikuni done in half hour mate.

george.gif

Re: Pulling my hair out over PHBG tuning

> Graham Motzing Wrote:

> -------------------------------------------------------

> yeah i was just joking that dude said he couldn't figure out how to tune

> a phbg then proceeded to give you bad tuning advice.

giphy3.gif

Re: Pulling my hair out over PHBG tuning

was there something about the silencer too? like it had an extra tube in it you had to shorten or something?

i was mostly thinking about the washer in the ball joint, but i've never owned one just talking shit.

Re: Pulling my hair out over PHBG tuning

> Mikey Antonakakis Wrote:

> -------------------------------------------------------

> Should just be in the ball joint.

>

> One tough part with a good 50cc kit and pipe (like you've got) is that

> the fueling requirements are vastly different from low to high rpm, much

> moreso than most moped kits. Gets worse when you port. Also not helped

> by the low compression ratio (at least for the water cooled kits) you

> get out of the box. My Peugeot Doppler kit was like 2mm squish out of

> the box? (And still is). It absolutely rips at high RPM but can hardly

> rev into the powerband. Best to just tune clutch and variator for high

> RPM use only, IMO. At least if you're okay screaming everywhere you go.

Yeah I figured it's good to run it cleaner in the bottom range to be able to rev it into the powerband and then fatter in the top of the range for when you're on the pipe. I just got back from tuning it and finally got a setup that is 90% dialed in, I thought I'd share if for anyone else who's interested:

-100 main jet (pretty much perfect, I may go up to a 102 thought just to see)

-42 pilot jet, mixture screw 1 1/4 turns out from seated

-Stock starter jet

-W12 needle set on second highest notch (runs clean until you have to open the throttle a little more to get higher RPM, 4-strokes for a second right before it gets on the pipe). I think a W11 needle might be perfect because it doesn't start metering fuel until slightly later, it may get rid of that tiny bit of 4-stroking but still keep it safe, either way I'm pretty happy with it right now.

- AU 262 atomizer

-#40 slide

-Treats 12v CDI with a Jog box set at 1.8mm btdc.

-B7HS spark plug

Idle temps are high 200's/low 300's and it doesn't get over 380ish on long WOT stretches. I need to put it through it's paces but so far it seems pretty spot on.

Thanks for all the help from everyone!

Re: Pulling my hair out over PHBG tuning

Can we keep this tread going please. I have almost the exact same setup and the exact same problem.

Ive been messing around with my phbg now for about 3 straight weeks and I'm sure my neighbors are ready to kill me and im just about ready to trash this carb.

Setup:

I'm at sea level or there abouts (California Santa Barbara low elevation)

PHBG

95 main

45 idle

stock starter

w7 needle 2nd notch down

miture screw 1-1/4 out from seated

30 slide

Timming

As per doppler instructions 1.2 degrees before tds

Pipe

Doppler (Removed restricter in ball)

Kit

Doppler 50cc

Variator

Er3

Spring

Doppler yellow

Reeds

athena carbon reed block

no air leak on engine

Verified with a leak tester.

0 consistency on starting, Some times it fires right up some times i have to kick it over and over. Once its running it will rev out just fine on the stand all the way to wot. I get on the bike and it runs ok but has very poor progression and takes a good while to get into the pipe. i have to search for the sweet spot on the throttle. Once in the pipe it runs like a banshee, full of power variates grate pulls hard but then... Once it I come to a stop it acts like it is fuel starved. Even after waiting a second bogs, bogs, bogs until it stalls and then I have to kick it over restart it. Restarts right away then runs fine again. I dont get it, I pull the plug and its not even brown. Closer to black even.

Ive cleaned the carb over and over found that i was missing the o ring in the mixture screw, and the cap for the oil injection plug. got that all replaced and no difference.

The only thing different is that i have a treats CDi with out jog box. Is my timming whats messing everything up?

« Go to Topics — end of thread

Want to post in this forum? We'd love to have you join the discussion, but first:

Login or Create Account