In our case in Tokyo, where we have just a Gerding King, Retro Hawks (HRs) run OK at 14.2v.
The present IRRA® motor rule change reminds me of my favorite bar in Tokyo, which closed after 40 years in busuness. I had been a regular client of it for over 20 years until the very end but I saw fewer and fewer people came there at its late stage. When the owner announced he would close the place in three months, all of a sudden, many clients, most of whom had been absent, filled the place to the capacity every night.
PDs have been almost dead in IRRA® racing these days. Personally I still have many many refurbed PDs as well as new ones and my raceway still has a dead stock of them but I believe it is time for IRRA® to simplify their motor rule.
As for PS4002FK for Can-Am Plus, I also keep lots of stock at my raceway. We raced Can-Am Plus a couple of times last year and many racers liked the class. Recently, however, I heard of serious quality problems with the motor. I got many sets of brush alignment fixtures from Chicagoland for us to prepare for the restart of Can-Am Plus this summer. When I talked to Kamo and other racers about what to do for PS-FK to run properly, their response was, "It would be too much for a sealed/non-refurbable motor." So we were considering locally replacing PS-FK for HR before the present IRRA® announcement.
Threre are lots of historical backgrounds of IRRA® motor rules.
The recent change may do damage to PD/PS-FK users, manufacturer, and related parties but it will be a good decision for Retro racing, at least for us in Tokyo.