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.