Some experimentation with the big Puch head. Does help to keep temps down a few extra degrees, but the largest difference in heat output was achieved when I filed out the two stator mounting holes, and rotated clockwise a couple of millimeters to retard the timing a little.
Unfortunately it's still experiencing some sort of rev limiting affect, as whenever I get super close to 5,000rpms, it falls on its face. There is a post in the comments section of this article (http://www.hondaexpressmoped.com/2009/11/honda-express-top-speed-nc50-max-mph.html) that pretty much describes my experience to a tee;
Hi, I'm new to the noped community, I bought a 1982 Honda Urban Express to ride back and forth to work and turns out I really like this little bike. It's in fairly good condition, but needs a good cleaning. I'm not very mechanically inclined but am learning all the parts, etc. I was reading your comment on a governer or rev limiter and how there is none, but I could swear that my express has one on it. I get up tp about 32 or 33 mph (it happens at the same speed every time) and you feel the engine stop accelerating, it just kinda cuts off, and you hear the rpms wind down and once it drops to a slower speed, like 30 or 31 mph it comes back on and accelerates just to cut out again at the same speed. Is this a govener/rev limiter?? (is there even a difference?) If so, how do I disable it? and if not, then what is it? Thanks so much for the help, I really like this website, there are a lot of interesting things on here and it will be a big help as I start to work on my express.
Still thinking that it may be some witchcraft within the factory CDI, i've gone ahead an ordered a Yamaha Jog 50 CDI and an A3202, since you Hobbit guys seem to be fairly split on what the best option is.