The Keihin PWK40 carburetor that you find for sale at many locations on the internet may not be exactly what you think.  There are companies out there, let's say over the pond, that are cranking out cheap knock offs.  We have all read DragBikeMike's thread about rebuild kits and the questionable quality parts some of those contain.  Well, here is some proof that even the carbs themselves can come with sketchy quality.  So much so I purchased two of them (since I did not like the first one I got).  The differences between the two is quite a long list, and I am still not finished documenting them.  Here is what I have found so far.  

The first carb I purchased on Ebay.  The seller was (and still is) Blackhary7.  The purchase price was $39.69, and it was delivered in a normal amount of time.  This seller is currently listing the same product, but now at $85.63 (as of 10-7-22).  The main thing I did not like with this carb was the plating on the slide.  It was covered in pits and nodules.  Coming from the metal fab industry as a career, I have dealt with a lot of different types of plating processes on many different base metals.  This lack of plating quality really disappointed me.  It was for that reason only I decided to buy another one from a different source.  For around $40 how can you go wrong?  The second carb I went with JFG Racing, since DBM had a good experience with the same product.  It was $34.99 at the time, and still is today (I checked).  This is what the plating looked like...

While looking closely at the air intake side of the carbs, I checked the slides.  The JFG carb had good quality plating.  I let out a little sigh of relief.  But then I noticed the slide had a different angle cut into it.  I haven't measured it yet, but they both came with a different slide.  The JFG carb also had a notch cut into the needle housing, where the first one did not.

After removing the float bowls, I found the inside of the JFG carb was wet.  Not sure if it's old fuel or a light oil.  The first carb was dry.   The JFG carb has a two piece main jet set up, the other is a one piece.

I will report more findings like jet size differences once I finish the disassembly and measuring.  Both of these carbs were advertised and sold as a Keihin PWK40.  What ends up going on my hot rod motor is yet to be determined.

Thanks for the photos and comparison Sneezy.  Two different animals for sure.  I'm wondering how these things end up with that removeable needle jet.  It may be some sort of modification they perform in conjunction with the enlargement of the carb throat.

I'm very curious about your needle and needle jet assembly.  Can you compare your needle to the needle chart I sent you?  Tell us how the JFG needle compares to that chart.  Give us an idea of approximately what series needle you have in the new JFG carb.  Would also be super-useful to know the size of your needle jet.  As I recall, Thunderino's needle jet was up inside the metering block and was captured by the threaded main jet holder.  This is a pic of Theduderino's.

This morning I disassembled the JFG Racing PWK40.  Here is what I found:

#170 main jet (no washer underneath)
#50 idle jet
#7 slide
Needle clip on 2nd groove from the bottom
Needle tapers from .096" down to .055" at the tip

Everybody hates filing. That's why they make grinders.

justin_o_guy2 wrote on 10/11/22 at 11:22:49:

 Good one, JoG!