Keihin PWK Advice

BM
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BM
Hi has anyone replaced there Keihin PJ carburetor out for the PWK air striker? I would like to replace my PJ 38 MM out with a PWK on my 86 CR250. Is t here a certain PWK that fits the older CRs like the screw top units ? What about jetting this carburetor for the 86 at 1500 feet above sea level. Thanks for any help.
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digger
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digger 6/8/2017 7:30am
6/8/2017 7:30am
A screw on top AS1 PWK should slide right in, They are 91mm in length from front to back. The jetting that was used back then on the 38 PJ's was a little different on the pilot due to the carb design, but the needle and main were similar. If it were my bike I would start out with an NEDW needle in the #3 clip with a 42/45 pilot and a 172/ 170 main jet, with the air screw at 1.5 turns out.
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BM
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BM 6/13/2017 5:50am
6/13/2017 5:50am
Thanks Digger i just purchased a used 39 mm PWK i have looked for that needle jet NEDW with no luck . I have parts numbers for all the slow jets and main jets. It show a list of the needles but not that one. I am searching in the KTM parts as the carb came off a 1999 KTM 200EXC .
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digger
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digger 6/13/2017 6:16am
6/13/2017 6:16am
BM wrote:
Thanks Digger i just purchased a used 39 mm PWK i have looked for that needle jet NEDW with no luck . I have parts numbers...
Thanks Digger i just purchased a used 39 mm PWK i have looked for that needle jet NEDW with no luck . I have parts numbers for all the slow jets and main jets. It show a list of the needles but not that one. I am searching in the KTM parts as the carb came off a 1999 KTM 200EXC .
The 39mm carb that you purchased jets slightly different than a 38mm PWK, that I gave you jetting info for. because it's slight larger at 39mm, it will require a slightly larger main. I'm thinking right around a 175/178. That carb also came with a richer #6 slide. The bike will still run fine, but it will be a little richer down low than it would be with a preferred #7 slide.

NEDW part #----http://www.motosport.com/oem-parts/part-number/13383-37FL0?mmysource=su…
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BM
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BM 6/13/2017 6:46am
6/13/2017 6:46am
Thanks again Digger your a wealth of well appreciated knowledge. Is this needle jet still be fine for the 39 mm NEDW. I was after a 38mm but i got a good deal on the 39mm. Being the same dimension it should fit inn the carb boot and air box just fine i hope. On another note after replacing my stock reeds out with the Boyesen reeds i am getting a popping sound in my exhaust when decelerating. I thought it may be lean or an air leak. I have a 60 slow jet and a 175 main a R1368N needle the 3 d clip down. The air screw at 1/1/2. I also put a FMF spark arrestor on. Its got me confused at what is causing it.. Thanks Again
BM
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BM 6/13/2017 6:49am
6/13/2017 6:49am
Also what slow jet would you suggest for the 39mm
digger
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digger 6/13/2017 7:33am
6/13/2017 7:33am
The needle jet and pilot jet will still be the same( 42 or 45 pilot) as it would be if you were using a 38mm carb. The 39mm carb will fit exactly the same as the 38mm pwk would. BTW,your current needle and main will work in the 38mm carb just fine, the pilot is the same style as a current pwk, but way to big for what you need. That 1386n needle jet is very similar to a CEJ single taper needle, which is still pretty popular today.


Check your spark arrestor to make sure it is not plugged. That would make it do what you are describing.
BM
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BM 6/13/2017 8:20am
6/13/2017 8:20am
I will check the FMF silencer its new so i cant see it being plug but its easy to put the stock one on to try. As far as the PWK I will start with the 45 slow the 175 main and the needle jet NEDW clip in the third position.

Thanks again
BM
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BM 6/14/2017 2:58pm
6/14/2017 2:58pm
Thanks Digger for your help i will get back to you when i get the PWK installed . I have contacted a Suzuki dealer at home to order the NEDW needle. The jets are easy to get from my local KTM dealer. Once i get this popping noise figured out an the new carb in i will be looking for another project. Next one will be old school air cooled like a MX6 Can-Am lol
Bramlett321
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Bramlett321 6/16/2017 12:21pm
6/16/2017 12:21pm
F1 Moto wrote:
Buy a Lectron !
Buddy if you could do this I can promise you all your jetting issues and problems down the road are over. I have one on my KTM and this is the best aftermarket part I've ever bought.
Brett Campbell 6/4/2020 9:00am
6/4/2020 9:00am
BM- Did you ever figure out what was causing the popping from your exhaust? I have the same problem and I am running Boyesen reeds also.

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