This is my latest idea so I can add weight to these PT cranks, trying to come up with a simple way to do it. Fit the pipe ring to the underside of the fanwheel and then fill it with lead. I made the ring 25mm deep and once I added the lead it had added 1.99kg to it. Next one I might make a thinner ring so I only all about 1kg. I poured this one with the fanwheel in position on the motor before I thought about the potential damage to the lower seal. I will set it up on a 24 base today and see if it will fire up. Hopefully if the seal is damaged I can remove the boss and fanwheel so I can fit it on another motor.
Just to confirm it fired straight up and runs fine, no attempt at kickback, makes PT motors on these an easy do now. Now I have to get some plates laser cut to allow me to fit PT motors on the F/C bases