a factory race kit was available for the ts90 which consisted of an expansion chamber, light piston and rings, carburetor, and harder (colder range) plug and head which increased the size to . in the north american market a 175cc race kit was available for the ts185. the 175 size was to match an established class. it consisted of an expansion chamber, new cylinder and head, piston, thin rings, larger carburetor, and much lower gearing. different gearing was available for most models. the tf model (mud bug) was developed in the early 1970s and sold mainly in new zealand and australia. the tf series was made in three sizes; 100 cc, 125 cc, and 185 cc engines. these bikes were based on the er range. the tf125 is still in production. it has left-and-right side stands with large bases, a large rear carrier, headlight and lever protection, a single seat, bash plate, large mud flaps and knobby tyres.