PWK 33 fine tune

denesdr · Post by **denesdr** » 10 Apr 2018, 12:12

Hello!

I have a feeling that I need to change the stock 6.0 throttle valve on my MK2 equipped with PWK 33.
I would like to ask if someone had to be replaced the slider?
At cruising speed in lower gears the bike is firmly "four stroking", which means a rich condition. I tried to adjust the air screw, idle jet, needle position, leaner (straight section) needle, unsuccessful.
The best option among them is a leaner needle, but the four stroking is still there. I put it in a more lean needle, but the bike runs too hot at part throttle and still four strokes below that.
So there are two more leaner slide a 6.5 and a 7.0, but which one to buy?
Is there anybody who has such experience in adjusting a PWK carb?

Thanks!
Denes

Post by **knackeredMk1** » 10 Apr 2018, 14:52

I have fitted two PWK 33s to CRM engines. In both situations I found going slightly leaner on the standard jetting was the best option but I could have got away with the standard jets. The needle with the original supplied with the PWK as standard sorry can't remember the details and no longer have access to the files.

I had no problem with 4 stroking on low throttle.

One was a slightly breather on Mk1 that was probably the equivalent of a Mk2 tuning. The other was a proper tuning for low/mid range, matching ports, overbore .....

Using a PWK gives a massive improvement to the throttle response and probably a little bit more power.

Bakers250 · Post by **Bakers250** » 21 Sep 2018, 08:53

Have you found a solution to this ?
I have tried similar but still running rich.

Post by **knackeredMk1** » 21 Sep 2018, 17:29

What jets are you using and what Mk do you have? Original exhaust system?

Bakers250 · Post by **Bakers250** » 22 Sep 2018, 12:18

Thanks for the reply.
Mk2 fmf gnarly and fmf pipe
45 pilot
128 main
Cgm needle pos 1
Premix

Post by **knackeredMk1** » 22 Sep 2018, 14:07

Is that needle clip on the top slot or the bottom?

Bakers250 · Post by **Bakers250** » 22 Sep 2018, 14:11

Post by **knackeredMk1** » 22 Sep 2018, 14:56

I would definitely try going down to a 125 main or possibly one more if you need to.

Bakers250 · Post by **Bakers250** » 22 Sep 2018, 16:23

Thanks Knackered
I have a few jets to try

denesdr · Post by **denesdr** » 23 Sep 2018, 06:57

Hi Bakers250!
My bike is an MK2 with original chamber. I use a CGN needle at middle position, but tried a CGQ (leanest) and the bike hesitates and runs hot with it so i went back to CGN. I tried a 120 main jet, but thats for another reason and this has nothing to do with the low RPM, barely open, part throttle four stroking. I using now a 38 pilot jet and this is sligthly better but the bike still four stroking an loads up with fuel at low RPM.
This phenomenon did not occur with the original carburettor. So the only part left is the slide. On another forum a guy said, the only cure for his bike to prevent four stroking was a leaner slide. So i would definitely try a leaner slide in the near future and report back what i found.

Bakers250 · Post by **Bakers250** » 23 Sep 2018, 11:04

Hi Denes
Just looking on a KDX forum as it has pwk33/35 as stock. R1173N needle similar to BGP needle is popular.
I’m experiencing rich running from 1/8 -3/4 throttle. WOT is fine.

http://www.kyajet.de/?lang=en this is a helpful jetting calculator!

Will report back when I get somewhere.

PWK 33 fine tune

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