Having owned my RD400F for 12 years I decided it was time to restore the old girl. After spending a lot of time restoring the parts, one area for real concern was to place the engine in the frame without damaging the frame or the engine. My solution is simple! I used foam insulation, the type used to lagging your domestic heating system. I placed this around the frame as you can see in the picture. It worked perfectly – no damage! Result.