Thanks Lancer.

The issue seems to be the restrictive pipe in my case. I think I will try removing part of the baffle and see how that goes.


I really don't like the look of the dyna mufflers

"The issue isn't present at WOT. Sorry if my wording made it appear this way. It is present at 3/4 (maybe slightly past) while at higher revs."


"This presents itself as great performance at WOT (no backfire or issues at WOT at all) and all through the rev range until just before the main jet takes over from the needle jet. At this point (and to be clear, I can deal with this issue and have fun riding regardless) it starts to break up and sputter, but the sputter  stops if I increase or decrease the throttle.  So to get this problem to appear on needle clip position 2, I have to hunt for it. Position 3 it's present over a wider section of the throttle range, 4 more so etc, with position 1 having it not present at all but being too lean all round."

Given that it takes WOT without any misfire, it seems unlikely that a restrictive exhaust is the culprit.  If a restricted exhaust was causing the problem, the misfire would get progressively worse as you gave it more throttle.  However, I do think a bona fide muffler will serve you better.


"I just did a quick ride with the slip on tail pipe removed. Performance was slightly better over all and I couldn't find the 3/4 throttle stutter."


So, once again your performance improves when you remove the pipe extension with the crazy baffle.  You feel it's too rich at 3/4 throttle, but all other throttle positions are good.  It's fine at WOT with a #140 main. All of that indicates that you could use a needle with less taper, but when you drop your current needle, you think it then goes lean in all the other throttle positions.  It's the craziest problem.  I'm baffled (sorry, I couldn't resist).

Do you have a dial caliper?

Lancer, these PWKs behave exactly like your VMs.  They are a bit harder to dial in because the needle jet and main air bleed are fixed orifices, but they behave exactly like a VM.  You wouldn't have any trouble dialing one in.

IMO, the VM runs a bit cleaner, while the PWK makes a bit more power.  The VM is a bit more flexible since there are so many readily available parts (needle jets in particular).  Once dialed in, I really can't tell the difference.  They run almost exactly the same (seat-of-da-pants).

The only reason I started messing with the PWK was the challenge.  I wanted to see if I could get one of these cheap knockoffs and make it work.  Turned out to be easier than I anticipated.  After I finish playing with the new PWK with the E-Tube, I want to revisit the old S&S super E.  I have some ideas I want to try to see if I can iron out the rough spots.  The S&S made lots of power at WOT, but it was a bit crude everywhere else.  It was a hotrod.  There's just nothin sweeter than having something totally different than everyone else, and also having it work good (like Versy's QuickSilver).

You can use that dial caliper to do a comparison of the needles.  I find that it helps me understand what's goin on with a particular needle, and it really helps when dealing with an unmarked needle.

As long as the caliper is metal and the jaws/anvils are ground square, it works great.  Set the caliper at a size that grabs the needle close to the bottom, then lock the caliper with the thumbscrew. Place the two needles in question side by side in the caliper.

Like this.

Then open the caliper up a few more thousandths.  Check the needles again.  The needle on the right is way richer.  It's a good quick & dirty tool for comparing needles.  The visual information helps me understand what I'm dealing with.  The instrument is not nearly accurate enough to do a useful dimensional inspection of a single needle, but it's a great tool for comparing one needle to another, especially when one needle is marked and the other is unmarked.