Hi Enildo and Panos,
This is quite an interesting 'puzzle'.
In styles where the 'crash' sound occurs, as far as I can see (hear?) it seems to always use the current sound in C#2 (MIDI note 49) of voice (drumkit) currently used for the RHY2 style part.
To check this out I modified a preset drumkit on my Tyros4 so that it used a hand clap sound for MIDI note 49 instead of a cymbal, and saved it as a 'Custom Drum' voice. Sure enough, when the RHY2 part of the style was revoiced with this modified 'custom' drum kit, the 'crash' sound changed to a hand clap.
As Enildo says, this happens even if the C#2 notes at the end of the Fill In sections of the style are deleted, so it does not seem to be these that are triggering the 'crash'!
However in styles where the crash does not occur, I have not been able to add one!
The format of a specific style does not seem to be the only issue here, since I have an SFF1 style which produces a crash! However this may have originated from an SFF2 format style which has subsequently been converted to SFF1 by someone! It could also be that it is something that is only recognised and triggered on a keyboard with an SFF2 native format style engine.
I don't really use the 'Cancel' chords, so to me it is only of academic interest, but it would still be interesting to work out exactly what triggers the 'crash' and see if it could be inserted into any style at will, even if this needed to be done by a computer using MixMaster or the like, which offer far superior editing capabilities to Yamaha's Style Creator on the keyboard.
Regards
Ian