Hi Zomby,
Here is the story on the different heads used on the NE motor.
The very early motors sported a head with same pattern used on the WC-1 motors, but had the island removed. Removing the island was originally a design used by "Weber" in the late 1940s, and increased the flow considerably. Sadly the early NE heads had a really deep chamber and a lot of deep tool marks where the island once resided. After a lot of work to smooth the chamber and mill .065" ~ .085" from the bottom, the head suddently became a serious contender. I am not sure of the reason, but Whizzer USA suddently re-designed the head and offered what I consider the "worst" combustion chamber design ever attached to a flat head motor in the last 100 years. Sadly the majority of the NE motors used this head, and I would guess approx. 90% of the heads were this version. I was able to re-work and mill this version to make it much better. This version of the head is easy to identify by looking at the intake valve pocket. I will include photos of both, and you can easily see the difference.
In the very last production NE motors a different combustion chamber design was employed [I could suggest where the idea came from, but why bother] and after a little TLC really upscaled the power output.
Now the facts, the early NE head [most likely the one you have] produced speeds in excess of 70 MPH on a dyno. The heads used on the late 2005 to mid 2007 had problems finding the 60 MPH speeds on the dyno, and the very last production heads once again bumped the 70 MPH numbers. All the heads I tested were milled & modified, but the early 2005 NE & the late 2007/early 2008 were powerful, and also very rare!
Most of the first edition heads when milled produced 120 to 125 pounds of compression. The midrange heads when milled & modified supplied an average of 110 pounds. And the rare final edition once again produced the 120 to 125 pounds of compression.
I use a "Craftsman" compression guage. I had to special order the adapter to fit the smaller 10 MM spark plug hole. It is important to open the throttle to wide open during the test.
These comments aren't meant to "bash" any company, person, persons, or vendor.
Have fun,
