the ts185 is lighter than the 125 by a few pounds, and has nearly the power of the 250 but with a much more free revving motor. the 250 is heavier than the 185. the larger ts series, 125 and over had piston port engines while the smaller ts series-90 and 100 had rotary valve induction, until the introduction of the er series motors. with the only major redesign of the motors of this series, the new range shifted to a combined reed-valve and piston port type.