The enrichment air passage in the new E-Tube carb is smaller.  It’s only .199”.  So, the enrichment circuit on the new carb feeds way more fuel and less air.  That explains the overly rich cold start.  I think I might be able to fix that problem.

As always, great write up and thanks for sharing!

Aside from the enrichment circuit, it seems like this PWK40 with E-tube is a winner.  Who is the seller?

Does “E-tube” mean “enrichment tube”?

Did it come with jumbo jets like the other PWKs we’ve tried?  I swear they set these things up for a 250cc 2-stroke from the factory.

OH!  How do you rack up 100,000 miles in ~2+ years!!  

Hey Paul, how's the Honda?  

If you go back to the beginning of this post, you will see the specifics on the Amazon seller in reply #1.  

I noticed that on reply #31 you mentioned you were running a #40 pilot jet and a #145 main jet with good results.  Do you recall if your PWK had an emulsion tube like the item I show in reply #8?  Was that one of these E-Tube carbs?  

BTW, the "E" stands for emulsion tube, see reply #8.  I thought the PWK you installed was one of these newer carbs with the emulsion tube, and I recall that in a different post I did on main air bleeds you mentioned running a #162 main jet.  What am I missing?



Hey Zevenenergie, how are you?  That is a beautiful set of hole micrometers.  I bet those cost a fortune.  Are the graduations .01mm (.00039").  If so, Wow!  What a nice set.  They look like they would be perfect for measuring valve guides.

Do you have one of these E-Tube carbs?  What can you tell us about it?  

Hi Mike, I'm fine, doing lots of divergent things.Thanks for asking.

I don't have an E-carb. I'm still riding with standard carbs, which I've made a bit more aerodynamic on the inside.

I was able to buy a whole set from 6 mm (1/4") to 60 mm (2.36 inch) from someone who closed down his business, at a very reasonable price. This Swiss brand is very expensive; the smaller ones cost $1,200 each if you have to buy them new, and the digital ones are completely unaffordable.

They are accurate to within 0.001 mm (0.001 mm = 0.00003937″).
That,s 0,01mm per graduation.And there is a vernier scale on them that brings it to 0,001mm.

I am often asked to repair worn bearing seats on 2-stroke engines, and that is what I bought them for, but they are also ideal for valve guides.
Now that I have these micrometers, I have eliminated the measurement uncertainty,and because of that you can work much faster.

Paul, I can't believe you unloaded that beautiful Honda.  Thanks for filling me in on the air striker.  It doesn't actually have an emulsion tube.  The air correction simply enters a passage that intersects the needle jet at the top, just below the venturi.  Those carbs work great too.

Zevenenergie, those are some amazingly precise instruments.  Makes me feel like I've been working with a hammer and chisel all these years. Thanks for sharing.