If you really want to go the Piston Port route under the current rules, I’d look at a pair of K71’s (AKA KPV, HPV).
Better quality than a Yamaha KT100. Not much more expensive to rebuild. Still uses a Walbro WB3a so tuning is similar. Each motor is about 5 pounds heavier than a Yamaha. And 3-5 more HP each.
Under current engine rules the K71 is very close to a Comer P51.
Since the TaG 125’s came in, there are a lot of K71’s available used. I bought 4 for under a grand.
November 15-19, 2017
Las Vegas, Nevada
SKUSA SuperNationals 21
2018 Events TBA