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Polini 34mm (Keihin PWK)... Jetting?

Want to know which carb to choose? Having problems setting up the jetting details on your scooter? Wheter you are using a standard or tuned carb, ask your question here.

Re: Polini 34mm (Keihin PWK)... Jetting?

Postby Adam_Winstone » Sat Sep 12, 2020 8:05 pm

WT1 thanks for the tip about modifying the float bowl to allow pilot jet removal, which has come in very handy of late.

Ta
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Re: Polini 34mm (Keihin PWK)... Jetting?

Postby Warkton Tornado No.1 » Sat Sep 12, 2020 9:57 pm

Adam, you are welcome :D

I imagine that you must be getting quite close to your definitive set-up by now......
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Re: Polini 34mm (Keihin PWK)... Jetting?

Postby Adam_Winstone » Mon Sep 14, 2020 7:33 pm

Nope :(

TBH I've continued to struggle with it, however, because this is an all new engine configuration it could be that other factors are causing, at least contributing, to my woes. So far I've identified and resolved an ignition fault but can't be sure whether other issues are still at play. As such, I'm going to make a move to a more familiar carb to see whether the issues persist, if so then I'll know that I need to be looking elsewhere. However, if I try a different carb and all my problems are resolved... then I might just launch this carb into orbit :lol:

Frustratingly, there have been times when I've thought that I was nearly there with it but then had the usual 2 steps forward and 3 steps back.

I'll let you know how I get on.

Adam
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Re: Polini 34mm (Keihin PWK)... Jetting?

Postby Warkton Tornado No.1 » Mon Sep 14, 2020 11:58 pm

Bl**dy Hell!

I can't believe how easily I have found the KOSO/OKO/Stage6/Chinese-Copy PWK's to set up by contrast to your issues.

The only slight initial concern was the pilot jets seemed small compared to what some others had said, but by following instincts, proved that to be the case & found plug chops to be textbook colour. Subsequently have read of others that have required pilot jets in low 30's & even smaller.

As for running with an adequate filter, I think they are superb.

I hope you can sort it :D
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Re: Polini 34mm (Keihin PWK)... Jetting?

Postby Leotech » Mon Sep 28, 2020 3:54 pm

A pal of mine had a genuine PWK and found it really hard to set up whereas I have an OKO and after 2 or 3 changes in jets and needle height its really good.
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Re: Polini 34mm (Keihin PWK)... Jetting?

Postby Warkton Tornado No.1 » Mon Sep 28, 2020 5:05 pm

Leotech wrote:A pal of mine had a genuine PWK and found it really hard to set up whereas I have an OKO and after 2 or 3 changes in jets and needle height its really good.


OKO are quite a serious supplier of PWK carburettor's in the USA & the quality seems good. They make them under license, as do KOSO etc. It's the Chinese versions that are questionable, but even then, they probably make 'their own' versions alongside licensed versions because they would not otherwise have the tooling, technology etc. That is the problem with China. Whilst the Western World remains frantic to take advantage of cheap labour & virtually throw technology their way, they think nothing of ripping off their clients to grab some money back. Not that I'm political in any way..... :lol:

I'm beginning to think that PWK's are causing confusion because they seem so easy to set, IMHO. I think I am quite fussy about getting carburation very close to the optimum, with just sufficient safety margin, but I have found that the abscence of a proliferation of expensive parts required to be extremely refreshing.

All that has been required, thus far, is a range of pilot & main jets along with a choice of needles, although only two needle variations have been necessary.

Out of interest, what configuration is your engine & the actual jetting details please? :D
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Re: Polini 34mm (Keihin PWK)... Jetting?

Postby Leotech » Wed Sep 30, 2020 8:29 pm

Cast iron home tuned 200, BGM V2 or 3

PWK carb OKO

Pilot 42
air screw 1 out
Main 128.
JJK top clip

Goes good.

I had one of these carbs a few years ago and ran it unfiltered and the chrome wore off the slide very quickly. This time I have fitted foam filter and one of those larger type rubber elbows that have recently become available.
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