Office of Steam Forum for Model & Toy Steam Gas & Hot Air Engines

The governor is much like the original it was modeled after but without adjustments.

You may be able to work around this by using a softer spring on the latch-out lever.

I think Gil has hit the nail on the head, I found this video on YouTube and you will see the owner has to put his finger on the latch out arm to even Get his engine to miss! His finger pressure is effectively cancelling out "some" of the the "to strong" spring effect.
  What I like about this video is the guy is very familiar with the previous model we all know and love, He makes Several attempts to stall his new engine when he see it is not properly missing and says "Wow, this has a LOT more power than the older model!

The 1/2 governor speed is not helping, so larger more heavy governor weights would help, there may not be clearance room for larger weights so polish all moving contact parts to reduce friction in the governor may help a little.
I would go as light as you can on the return spring, possibly even wind your own spring out of a thin guitar spring.
  When you mount the engine Very secure so it can not rock, when the engine fires, it puts "More" of its energy into spinning the flywheels so it is more efficient at getting them up to speed. The engine hitting several/many times before the governor finally does its job is a symptom of the overly strong spring.

It looks like they got several other things right on this engine, I might enjoy tuning on it if I can find one priced well!