I'll say this, the Hitachi is sensitive/moody.
A month or two later I'm still tweaking it !
After rebuild ran perfect for a few days, then just quit on the highway. I gave it a hillbilly rebuild on the side of the road and drove it home.
Filled the fuel bowl with carb cleaner and sat overnight and better the next day.
Carb tuning Choke/timing really makes a difference, VW bug carbs were just like them, If its out of whack it wont run right.
I wasn't getting good mileage/performance, and after messing with primary venturi setting and primary choke setting and readjusting carb and timing about 20 times it is actually running awesome and getting good mileage (about 28 overall).
The probs were the primary bottom plate/throttle cable and choke was out of adjustment.
The choke setting really makes a difference, of course you set it to open fully, but there is a sweet spot where it will fully open and still have a slight venturi effect.
Hope this helps somebody, it is possible to rebuild a Hitachi !
I'm still saving for a Redline Weber Kit...LOL