Keihin PWK38 Carb

Brett Campbell
I see that Honda still offers the Keihin PWK 38 Air striker carb for the 2000 CR250. Does anyone know the difference between that carb and the Keihin PWK 38 Air striker aftermarket carb offered by Keihin, other than jetting?
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digger
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digger 6/4/2020 4:48pm
6/4/2020 4:48pm
The 00’ Honda carb comes with a 7.0 slide, while the aftermarket Keihin PWK’s sometimes come with a 6.5 slide. I prefer the 7.0 slide for 250/300 bikes.
digger
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digger 6/5/2020 5:35am
6/5/2020 5:35am Edited Date/Time 6/5/2020 5:35am
I'm not sure of the efficiency of that particular engine, but I would start off with a J series starting diameter needle. I would start off with a Yamaha duel taper N89J in #3 clip, with a 45 pilot and 172 main jet. These should be safe starting points, and should get you in the ball park.

https://www.motosport.com/oem-parts/part-number/4JT-14916-9J-00?mmy=yam…
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Brett Campbell 6/5/2020 5:41am
6/5/2020 5:41am Edited Date/Time 6/5/2020 6:07am
Thanks for the info and the link, digger! I will report back when I get the carb installed.

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pj136
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pj136 6/9/2020 12:32pm
6/9/2020 12:32pm
digger wrote:
The 00’ Honda carb comes with a 7.0 slide, while the aftermarket Keihin PWK’s sometimes come with a 6.5 slide. I prefer the 7.0 slide for...
The 00’ Honda carb comes with a 7.0 slide, while the aftermarket Keihin PWK’s sometimes come with a 6.5 slide. I prefer the 7.0 slide for 250/300 bikes.
Sorry for jumping in slightly off subject, but digger would you be able to help with this.

Kx144 (athena kit) - vforce, pc pipe 2 stage igntion. Removed the makuni carb and fitted a pwk38. Revs clear on the stand, sharp off the bottom. As soon as you pull away it just dies roll the throttle off and comes back to life.

Kx125 1989, vforce 4, ported barrel, pc pipe, 2 stage ignition. Same as above removed the 35mm fitted a pwk38. Sounds crisp on stand revs clear and sharp off bottom as soon as you pull away it dies roll the throttle off it comes back to life. 

Any ideas, ive changed jets moved position on needle. Tried dropping slide to a number 6. 

Have read on here about someone fitting a no4 slide and different needle but cant refined the post
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digger 6/9/2020 5:18pm
6/9/2020 5:18pm
What jetting do you have in the carb currently, needle, pilot, main, slide ? Is this an AS 1, screw on top, or AS 2 Pwk, short body top held on by screws ?
pj136
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pj136 6/10/2020 10:20am
6/10/2020 10:20am
digger wrote:
What jetting do you have in the carb currently, needle, pilot, main, slide ? Is this an AS 1, screw on top, or AS 2 Pwk...
What jetting do you have in the carb currently, needle, pilot, main, slide ? Is this an AS 1, screw on top, or AS 2 Pwk, short body top held on by screws ?
89 125 - 55 pilot 160 main, No7 slide, without looking i cant remember what needle but on 2nd groove down from top

06 kx144 - 50 pilot 180 main No7 slide NOZI needle middle clip.

Both carbs a screw on tops
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digger 6/11/2020 5:20am
6/11/2020 5:20am
pj136 wrote:
89 125 - 55 pilot 160 main, No7 slide, without looking i cant remember what needle but on 2nd groove down from top 06 kx144 -...
89 125 - 55 pilot 160 main, No7 slide, without looking i cant remember what needle but on 2nd groove down from top

06 kx144 - 50 pilot 180 main No7 slide NOZI needle middle clip.

Both carbs a screw on tops
On the 89' 125, I really need to know what needle you are trying to use. It simply may not be usable in your bike. The needle is the most important tuning device in the carb and the ends( pilot & main) will get tuned around it.

On the 06' kx144 with the #7 slide. I don't see how you will be able to use that NOZI needle. That needle has a pretty rich 1st, but short first taper with a lean starting diameter, which doesn't bode well for when trying to use it in a small bore bike with that lean of a slide.

Now that the Honda triple and duel taper needles have been discontinued, I have better luck using the single taper needles. On the 89' bike, I would recommend a CCK needle and for the 06', I would recommend a CCL needle. Your pilot and main look pretty close on the 06' for the CCL needle, but the 160 main on the 89' looks lean to me, but the pilot should be a good starting point for the CCK needle.

https://www.jetsrus.com/a_jets_by_carburetor_type/needle_keihin_N427-48…
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deccr250 6/11/2020 12:29pm
6/11/2020 12:29pm
digger wrote:
On the 89' 125, I really need to know what needle you are trying to use. It simply may not be usable in your bike. The...
On the 89' 125, I really need to know what needle you are trying to use. It simply may not be usable in your bike. The needle is the most important tuning device in the carb and the ends( pilot & main) will get tuned around it.

On the 06' kx144 with the #7 slide. I don't see how you will be able to use that NOZI needle. That needle has a pretty rich 1st, but short first taper with a lean starting diameter, which doesn't bode well for when trying to use it in a small bore bike with that lean of a slide.

Now that the Honda triple and duel taper needles have been discontinued, I have better luck using the single taper needles. On the 89' bike, I would recommend a CCK needle and for the 06', I would recommend a CCL needle. Your pilot and main look pretty close on the 06' for the CCL needle, but the 160 main on the 89' looks lean to me, but the pilot should be a good starting point for the CCK needle.

https://www.jetsrus.com/a_jets_by_carburetor_type/needle_keihin_N427-48…
Sorry to hijack the OP’s thread....digger, I’ve just sent you a message regarding jetting a PWK carb, hope you don’t mind Smile
pj136
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pj136 6/12/2020 1:29am
6/12/2020 1:29am
digger wrote:
On the 89' 125, I really need to know what needle you are trying to use. It simply may not be usable in your bike. The...
On the 89' 125, I really need to know what needle you are trying to use. It simply may not be usable in your bike. The needle is the most important tuning device in the carb and the ends( pilot & main) will get tuned around it.

On the 06' kx144 with the #7 slide. I don't see how you will be able to use that NOZI needle. That needle has a pretty rich 1st, but short first taper with a lean starting diameter, which doesn't bode well for when trying to use it in a small bore bike with that lean of a slide.

Now that the Honda triple and duel taper needles have been discontinued, I have better luck using the single taper needles. On the 89' bike, I would recommend a CCK needle and for the 06', I would recommend a CCL needle. Your pilot and main look pretty close on the 06' for the CCL needle, but the 160 main on the 89' looks lean to me, but the pilot should be a good starting point for the CCK needle.

https://www.jetsrus.com/a_jets_by_carburetor_type/needle_keihin_N427-48…
Digger
Needle on the 89 125 is currently a JR2070.

With the needles you've recommended should i still run the No7 slides ?

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