Polini ZA50 19mm PHBG Idling issues


So I’ve consulted the many guides that talk about phbg tuning but I’m having some issues. I have a polini 64 kit on a ZA50 with a 19mm phbg and foam air filter.

When this engine was running and ripping in VIRGINIA it ran a 88main jet, 50 idle jet and the 60 choke jet.

Now I live in NH with a much higher elevation and am having a hell of a time getting this to idle properly.

I immediately upjetted to a 94 main just to be safe from a seize and I can tune that down later if needed.

The za wouldn’t idle well for me until I put in a 52 idle jet but based on what I’ve seen everywhere, that’s super high. Additionally the mix screw must be screwed in completely for the za to continue running.

Am I just vastly “overjetted” in my idle and I should be close to mid 40s for an idle jet?

Any help would be great. I’m trying my best here but I’m stumbling

Re: Polini ZA50 19mm PHBG Idling issues

Probably Fred /

Should be 3/4 to 1.75 turns on screw otherwise you’re not correct Idle jet,

and is for idle to 1/8 throttle brapbrap kinda 4 stroke sound at 1/8 throttle

Try 38-40 idle maybe

I’m at like 1,200 ft, I run polini reed cage with true rubber 4 petal reeds in it, a 90 degree polini space filter with no plastic cover, 94 main, I think 40 idle, almost 1.5 turns on air screw, 262 atomizer, # 7 needle with one clip rich setting,

Need more info:

What kind of foam filter (I hope not 2 layer uni filter yuck!)

What ignition ?

What timing setting?


Re: Polini ZA50 19mm PHBG Idling issues

Alright so I’ll have to order some smaller idle jets. I felt like 50-52 was way too high.

Currently running points, will have to check what I had it timed to, been almost a year since I messed around with this guy, suggestions or maybe something I can reference for timing?

Not sure the exact filter, big black foam filter, can’t find an exact copy on treats but here’s a photo of my ped so you can see it.

Thanks for the assist!

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