PWK carbs

I'm not sure this is a carb problem.
I bought these PWK carbs from JS motorsports. At around a sustained 70 mph, the bike starts to crap out. I drop down to below 70 mph and it clears up. I can ride around all day without any problems until I hit the freeway.
I called Jim a couple of times and he said it was loading up from being too rich. Told me to drop the needle. I did but no joy. I tried a smaller main jet. I went from a 160 to a 150. Still craps out at 70 on the freeway.
Like I said it may not be a carb problem.
It vents fine and the gas flow is fine.
I can ride as hard as I can on the twisties without a single problem.
What am I missing here?

First of all, check if the carburetors get enough gasoline. Disconnect the fuel lines and open the taps. Take refill in a bottle or something else.
Take the time and measure how much that flowed through and report back.

Those carbs get enough gas, that's not your problem. Changing the main jets won't help - that's only for wide open throttle. Put the 160s back in.

So it misses (cuts out) but no farting, popping or pinging right?

If it doesn't load up at 60 but loads up at 70, or if it runs clean at 65 but loads up in a head wind or when you roll on a little more throttle - then its still the needles being too rich and you will have to drop them another notch (raise the clip).

I have experienced this problem but I want everyone to start out rich rather than too lean and risk damage.

Be careful you don't go too far and lean it out to where its pinging or end up with the plugs being too white. If it pings - turn around, baby it home and raise the needles back to where they were.

I had the 160's in with the clip all the way up and it still won't let me cruise on the freeway with out craping out.
Is this just the way it is?

No

You will have to get a smaller needle jet (this is the brass tube the needle jet slides up and down in). Take out one of the main jets and main jet holder (brass and alum parts). Then tap the needle jet down and out from the top (after removing the slide) there should be a mark or number on the side of the brass needle jet. Tell me what you see (or if there is no mark at all). If there is no mark and all it is probably a .102" and I will have to send you a .101"

Or just send me a PM with your address so I can make arrangements to send you a pair of .101" needle jets. Otherwise your bike will be out of commission until you get the jets - or maybe you can get needle jets at your location. I wouldn't go smaller than a .100" needle jet and they may only be only be available in metric (I modified them with precision reamers). A .100" needle jet will need the needle clip no higher than the middle position. A .098" needle jet is too small for the needle.

You must be very careful when installing a needle jet and make sure it goes in straight without getting out of line when you tap it in. I use a long wire punch for this. Check as you go to see that it stays straight and don't force it.

PM sent. Thanks Jim