CMB 90 mods for rigger

[RobBinnie]

have a dead stock CMB RS EVO as per attached picture

engine is in one of Andy’s SGX 90 Hulls

What engine mods are you guys doing to these for heat racing on 50% nitro
Any help would be appreciated
Rob

 

[RaceMechaniX]

Clean up the case inside of course casting finish, remove the chrome flashing on the ports with a Cratex tip dremel bit, machine a small volume head button around 0.8-0.85cc, set the squish around .012”, check the disc clearance and machine down to .005-.007” clearance if capable. Timing numbers are pretty good from the factory.