Recommended jetting?

[JerryHawk250]

Originally Posted by crackerjac

I picked up one of these PWK clones for my OHC 223cc Zongshen motor, basically a Honda CRF230F(223cc) clone.


Has anyone dealt with this carb and can recommend some jetting to start with for tuning?


The CRF230 guys say 120 main, 45 pilot but I can't figure out if that's Mikuni, stock carb, OKO, or True Keihin PWK jetting.


I tried 45 pilot and had to turn the air screw out 4+ turns out (very rich) but the bike loved it, but rich. I've been going down in size to currently a 38 which is around 2 turns out but the bike stumbles when I blip the throttle. I'm thinking a 40 might be the sweet spot. How far out on the air screw is acceptable? Needle is is in the 4th from the top, I'm going to put it back in the middle and continue tuning.


I'm at 761ft above sea level. All trail riding.





https://www.aliexpress.com/item/3284...27424c4dAc5IIl

I'm currently running a 38 pilot and 125 main but my head is ported and decked. 120 might be better suited for stock engine. They use Keihin style jets.

[crackerjac]

Originally Posted by JerryHawk250

I'm currently running a 38 pilot and 125 main but my head is ported and decked. 120 might be better suited for stock engine. They use Keihin style jets.

Do you have the same carb?


120 main sounds about right, I ported the intake path to match the carb opening and have a open style air filter, free flowing exhaust. Other than that it's stock.


So I'm guessing I'm on the right path. Maybe a 35 Keihin pilot might be worth a try. How many turns is your air/fuel about and what is your needle clip on? I'm just trying to reference to ball park mine? I'm shooting for 1.5~2 air screw, sound about right?

[JerryHawk250]

Originally Posted by crackerjac

Do you have the same carb?


120 main sounds about right, I ported the intake path to match the carb opening and have a open style air filter, free flowing exhaust. Other than that it's stock.


So I'm guessing I'm on the right path. Maybe a 35 Keihin pilot might be worth a try. How many turns is your air/fuel about and what is your needle clip on? I'm just trying to reference to ball park mine? I'm shooting for 1.5~2 air screw, sound about right?

I have this carb but tuning should be close to the same.https://www.aliexpress.com/item/3237...16894c4dabE24C I'm at 1 1/2 turns out and needle raise one notch from center.

[JerryHawk250]

Did you port the exhaust side? I know on my Hawk it was very restrictive. Big improvement.

[crackerjac]

Originally Posted by JerryHawk250

Did you port the exhaust side? I know on my Hawk it was very restrictive. Big improvement.

Not yet, it's a winter or next summer project but I can see it's very restrictive.


I'm using a stock 2005 CRF250X exhaust with the silencer removed.

[crackerjac]

Originally Posted by JerryHawk250

I have this carb but tuning should be close to the same.https://www.aliexpress.com/item/3237...16894c4dabE24C I'm at 1 1/2 turns out and needle raise one notch from center.

What size did you end up buying? The 30mm? The manufacturer says all the slide sizes are the same and if you get a rich idle circuit that can't be fixed with jetting you need to go up a size in carb. I wonder if the 30mm I bought is too small going by their size/HP CC charts.

[JerryHawk250]

Originally Posted by crackerjac

What size did you end up buying? The 30mm? The manufacturer says all the slide sizes are the same and if you get a rich idle circuit that can't be fixed with jetting you need to go up a size in carb. I wonder if the 30mm I bought is too small going by their size/HP CC charts.

I got he 30mm. I think 30mm smooth bore is perfect for these engines.

[crackerjac]

Originally Posted by JerryHawk250

I got he 30mm. I think 30mm smooth bore is perfect for these engines.

Out of curiosity, what did you set your float height at? I know the proper way is to use a tube off the float bowl but there is no nipple on these so unless I get another cap for the bottom and drill and tap a fitting to do the tube method I just followed the OKO sites method and set it to 21mm, which appears to be a similar carb.



http://www.mid-atlantictrials.com/Instal.html

[JerryHawk250]

Originally Posted by crackerjac

Out of curiosity, what did you set your float height at? I know the proper way is to use a tube off the float bowl but there is no nipple on these so unless I get another cap for the bottom and drill and tap a fitting to do the tube method I just followed the OKO sites method and set it to 21mm, which appears to be a similar carb.



http://www.mid-atlantictrials.com/Instal.html

I just turned the carb upside down and made sure the seam of the float was parallel with the carb body.

[el-griffo]

Originally Posted by crackerjac

What size did you end up buying? The 30mm? The manufacturer says all the slide sizes are the same and if you get a rich idle circuit that can't be fixed with jetting you need to go up a size in carb. I wonder if the 30mm I bought is too small going by their size/HP CC charts.

hi there, i'm confused (not difficult!) i would have thought that if the rich idle cannot be fixed by jetting a bigger carb would be even richer?


i have the same zong 230 crf clone engine and i put a pwk32 on it but it was way too rich in idle and i couldn't jet it down enough.


all the posts on the crf230 forum say a pwk28 is perfect for the stock engine.



apologies if i am talking rubbish - anyone put me right on this?


thanks.

[JerryHawk250]

Originally Posted by el-griffo

hi there, i'm confused (not difficult!) i would have thought that if the rich idle cannot be fixed by jetting a bigger carb would be even richer?


i have the same zong 230 crf clone engine and i put a pwk32 on it but it was way too rich in idle and i couldn't jet it down enough.


all the posts on the crf230 forum say a pwk28 is perfect for the stock engine.



apologies if i am talking rubbish - anyone put me right on this?


thanks.

A pwk32 is way too big a carb for the stock engine. The pwk28 is a perfect match. I'm using a PWK30 on my Venom X22R but also have ported the head and 11:1 compression. Bigger is not always better.