Best bike for track making?

[RBp]

Im confused.

Been testing the tracks with the default 990, This bikes seems to go round everywhere okish, If I try with the 500/125/R6  they crash a lot more and on corners which you would not expect. Is there something wrong with the bikes compared with the 990 or should I make tracks which the 125 can't crash on if that possable

[Alby46]

125