Taking a page out of DragBikeMike's playbook I will be installing a PWK38mm Air Striker Carb.  I was going to do this mod later with some other mods, but I destroyed the air/fuel mixture screw on my stock carb, so here we go.

A couple years ago with Mike's help, I installed a PWK40 on a S40 I had at the time.  It worked well, but in the end I would say it was too big, needed bigger jets, and I probably wasn't feeding it enough air (stock air box and flat panel filter), and pretty open Jardine exhaust.

I bought this carb on Amazon from JFG Racing for $36.  It's pretty nice.  I'm not sure what to think...  For the price, it should be a knock-off, but it's plastered with Keihin and Sudco...  I wonder if they bought these from Keihin as some "2nd quality" wholesale.

Link --->  https://www.amazon.com/dp/B07MMJV6BT?ref=ppx_yo2ov_dt_b_product_details&th=1


More pics and comments/steps coming.

Air Striker View.  The air striker flow channels supposedly concentrate air flow over the main fuel curcuit to increase low end throttle response.  

Even without the air striker feature, these semi-flat oval slide carbs provide superior throttle response.  No waiting for vacuum to lift the diaphram like in the stock CV style carb.  It's actially the best part of these slide carbs in my opinion.

Right Side View.  There are 4 vent tubes.  The top 2 vent tubes are functional float bowl vents.  The other 2 below those are not drilled through.  For some "quad vent" applications like on 2-stroke dirt bikes, these get used somehow.  I'm not up to speed exactly how that works.  (Crash the dirt bike and it has 4 vent tubes to pee out of??)

Air intake side has 63mm OD and about 57mm ID.  The 2.5" ID "turbo tube" fits nicely.

Test fit of the throttle cable ferrule in the slide catch contraption.  This will test your patience putting it together.  

This is a test fit outside of the slide before trying to insert the cable ferrule in the contraption while inside the slide.

It came setup with a #170 main jet and #50 pilot jet.

Using DBM's setup for his bike as a guide , I have installed a #138 Main and #35 Pilot, with e-clip in the 4th groove down on the needle.

It has a float bowl plug.  You could theoretically change the main jet without removing the entire float bowl.

Note: I swapped out the float bowl JIS screws for M4-0.7x16mm stainless steel allen head screws.

The silicone "turbo tube" I will use to connect to the air bix.  It's 2.5" ID and 8" long.  I will cut to length (like 5.25" - 5.5").  

Check out those monster t-bolt clamps that came with it.  Those will probably need to get swapped out for some narrower worm gear clamps.

The 2.5" ID makes a really nice fit even before clamping.