Switched to a 19mm polini cp and hate it

Michael Gamba /

Oct 15, 2021 01:32PM

I have had this polini cp19mm carburetor for a while now got it brand new finally decided to hook it up and man I'm not happy with it running as close to the jetting I had while.i was running my lsdtrp21mm oko clone and it's a dog tried a few different jets cant get it to run any smoother or idle. And for some reason it will not stop leaking from the breather line that comes outta the bottom of the carb. Was hoping this polini I paid way to much for would be better then this cheap oko clone but sadly not yet i hope once i get it dailed in and get the bugs out it. Any idea why it wont stop leaking from the breather line?

Re: Switched to a 19mm polini cp and hate it

Andy f kin Scouten /

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andyscouten

Oct 15, 2021 01:51PM

Those carbs are designed with reeds in mind, but we've run em on plenty of pp motors

make sure the air break jet is blocked off

get a range of needles

grab some idle jets

the main will not tune the same as your oko due to the atomizer

get that head temp sensor out and tune, or start doing some plug chops

Re: Switched to a 19mm polini cp and hate it

Graham Motzing /

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grahammotzing

Oct 15, 2021 02:20PM

Was actually thinking about making this swap myself, got a 19 phbg clone that works great but it has a dead spot I can't fix and it don't have a removable atomizer.

Andy do you always block the air brake jet or is that just a PP thing? TBH I'm a little rusty on PE carb tuning, haven't messed with one in ages. I'm gonna run it on my puch polini.

Re: Switched to a 19mm polini cp and hate it

baird co /

bairdco

Oct 15, 2021 07:13PM

If it's leaking, pull it apart and clean out the needle and seat. Make sure your floats aren't cracked (or melted. The first ones treats had weren't rated for our fuel, and the ethanol melted them.) Floats aren't adjustable.

Jetting on my kitted V1 is a 95 main and I forget the pilot. I think it's stock, like 34?

The jetting numbers probably aren't the same as your old carb.

Check those two rubber caps and make sure they're sealing.

The air screw on the side should be 1 1/2 to 2 turns out. Looks like yours is all the way in.

Check for air leaks everywhere, and run a fuel filter.

And no, they weren't designed for reeds only. It's just a carb. It'll work on anything

Re: Switched to a 19mm polini cp and hate it

Daniel '' /

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deesal

Oct 15, 2021 09:38PM

So did it run ok with the oko or did it run like shit too? That set up is not really the easiest to tune, both the 72cc and 74cc kits have their own issues. For both of them you usually have to stack a shit load of base gaskets or a metal spacer to get the compression ratio close enough to run more than a block or two before shutting down. You could also turn that head on a lathe too, but most people don’t have easy access or the tuning know how to correct it.

Re: Switched to a 19mm polini cp and hate it

Marky Mark /

markb82

Oct 18, 2021 07:08PM

I have a polini cp 17.5 mm on a plane 44mm airsal Doppler single petal er2 Reed 18mm phbg tomos Intake couldn't believe speed flys. Took it from 45 to 65mph richest needle setting. #72 main #38 pilot 27-20 gearing

Re: Switched to a 19mm polini cp and hate it

Michael Jones /

thejones_lbc

Oct 19, 2021 03:57AM

I have a cp17.5 on a Polini 64cc kit. It took a lot of digging to get it set up, but I think it is performing well if thirsty.

I didn't get anywhere before I had the air brake jet from Treats, check the rubber caps, there are hoses in the box you don't need... There is a lot to this carb that you don't need on a 2 stroke.

Mine will also take a piss on the floor if I leave the fuel line open. It seems to be a feature to prevent fouling the carb with fuel/oil. When the vacuum dissipates, all but the bottom of the float bowl will drain.

I think this might be why the CPs need the choke for starting, they are self drying. With a Bing, you can start it up and get down the block before you realize the fuel petcock is still closed.

Re: Switched to a 19mm polini cp and hate it

Born to be WillD /

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willd

Oct 21, 2021 02:07PM

Oh man, I ran a CP21 on an AV10 and it was great except for the needing special jets. Theyre real similar to the OKO's since theyre all PWK based

but man, i've run that kit on an e50 and it was a real chore to dial in, felt like it had a really different demand, like tune the topend high RPM and low speed WOT was wonky etc. But that was with a VM which is maybe more forgiving but less tunable, I feel like it'd needed a better balance of main vs pilot, just needle/main didnt cut it. And like usually I'm at a pilot close to half the main, but that kit I think wanted a smaller pilot

the leaky is almost definitely the float needle seat

you have to plug both tubes at the engine side, they've got a lil bung for a vac petcock, and one for oil injector, i just used a small line and connected the 2 with a U

They're pretty sensitive to needle and atomizer, make sure you've got the 2t atomizer (no holes) but I think blocking the air brake just makes the 4t atomizer effectively a 2t. But I think for that kit, the idle jet's gonna be more important and I think it was lower than I'd normally expect.

These are some dusty memories so dont give my thoughts too much weight.

MOPED ARMY

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