Help me verify this is a PWK 38 and why was there a change from the PWK 39?

[Hawkeye58]

Hi all,
Please help me verify my carb is a PWK 38.
Also, why did team green change from the PWK 39 to the PWK 38?

[sandblaster]

Well... I can tell you what it is not...
It is not a KX125, KX250, or KX500 of any year.
Anything in the V800 range is early to mid Kawasaki as the V800's were discontinued on the dirt bikes around 1995.
Why did team green go to the 38mm?
Because the 97 KX250 used a 38mm Keihin Air Striker which is a superior carburetor in every way.
It will add 1 hp to the rear wheel on a completely stock KX500.. That is dyno confirmed.
The flow bench shows that it does just as well as a 41mm Airstriker for volume and velocity. That is also dyno confirmed...
As a bonus, it gives you more torque on the bottom end

[Hawkeye58]

Sand Blaster,
Thanks for the information.
Though that is a bit depressing. I now wonder what the prior owners of this bike were doing?
What this carb really is? I have had the 500 for almost four years, it hasn't really ever run to it's full potential.
I keep improving it, and now desire to figure out this carb.

Hawkeye 

[Hawkeye58]

The Carb has a #7 slide,  and a N82R Needle.

Hawkeye 

[Hawkeye58]

Sand Blaster could this carb have been the stocker from when the bike was built. It's a 1993 KX 500.

[Hawkeye58]

I have a update...
I just got a response from customer service at Keihin/Sudco in CA.
The person there informs me that the number for my carb is the stock PWK 39mm installed on a 1993 KX 500.
That helps me out. That way I can go by the proper charts.

[sandblaster]

KEIHIN PWK V563 FITS 90-93 KX500 - 39MM

They have the wrong number and the wrong size  
I have owned and parted out many of the 90-93 K5's and they all had the same numbers.

Of course if your carb is in good condition and jetted correctly then run it.

[Hawkeye58]

10/4
That's what I am trying to do with it.
I got the cylinder done by Millenium Technologies, and I sent my head to Larry Weichman for his mod.
Now I am working on my jetting with Las Vegas air getting down to 60 - 70 degree highs, and at approx. 2800 ft. altitude.
The bike hasn't bee cooperative yet in the 1/4 to mid ranges. I then came here seeking this carb info.
I have been running a: 165 Main
                                  52 and 55 Pilots
                                  N82R Needle at several positions, currently at #3
                                  air screw is at 2 turns currently, had been at 1 1/2

I think it's lean. The plug looks more grey than tan, and the low end is burbling a lot in the technical sections of washes.

[Friar-Tuck]

Get ahold of KXPegger, , (Pete) 
 Great Guy, Wealth of knowledge, and always willing to help.
 Living / riding out of Vegas on several brand Bikes for years.
   Tuck\o/

[kxpegger]

Fresh to semi fresh motor/reeds.

55 pilot
168 main
#7 slide
N82M needle

These are for desert floor 2500ft mid to high speed and if visiting 70 mph or faster sustained you may want to go 170 main. I'm running a gnarly pipe and stock reeds. If you are riding slower more technical stuff then maybe a 165 main and 52 pilot. I ran a 52 pilot for awhile and although snappier off the low end no matter how I tuned the bike there was surging when letting off the gas. Every engine and tuning requirements are different but this is a good base line to start from. I run premium pump gas and 40:1 pre-mix. Hope this helps!

[Hawkeye58]

Thanks for your input guys.
I am currently running Amsoil at 50:1 and that is adding to my jetting project too.
I rode this last Saturday.
I went with,
165 Main
48 Pilot
Needle at 4 pos.
airscrew at 2 1/4 turns out
I was up at Beatty NV which is almost 3000 feet.
in the Morning at approx. 50 degrees it ran Beautiful with very little burbling at the 1/8 throttle position.
Later in the day as it approached approx. 60 degrees  it ran with a fair amount of burbling at the 1/8 throttle area.
only in the tight technical stuff is this going on. Always doing well else where, and plenty of strong pull mid to full throttle.
Gaining ground here but, still not quite there yet...

Hawkeye

[kxpegger]

Stock pilot is #58 from sea level to 3000 ft. Team Green #55. Stock plug is BR8EG and Team Green ran a B9EVX. I run a shorty on my AF BR8ECMIX because of clearance issues. Plenty of dense air left at 3000 ft. #48 seems on the small side. Wonder if something else is causing your issue besides jetting?

[436m]

I would pressure check the engine, In my experience when the jetting gets "out of the normal ranges" there is un metered air involved

[KXDINO]

I don't know if k5 carbs have a jet block gasket or oring , I never had that drama but some carbs do and if they leak there it can cause tuning dramas anyone know , I don't want to take carb out to check I just wanna ride em.

[reklessj]

Ya might also get the proper screw in there for that idle screw. Not sure how that could be affecting things. just sayin