YAMAHA DT1C-MX

Technical Details

Year Built : 1970 Engine : 250 cc Two-stroke single, Pre-mix required Transmission : 5 Speed Electrics : Nippon-Denso magneto with internal rotor & points ( DT2-MX type ) Notable Features : Yamaha's first 250 cc DT1 model with a factory installed high-performance GYT-kit was the 1969 DT1-S, For 1970 the tuned-up off-road only scrambler became the DT1C-MX, In reality simply using " MX " in the nomenclature could not make the DT1 competitive with European brands but from a marketing aspect it sounded good. Yamaha's frame, forks, and shocks did not have the strength to match the other makes but the Yamaha motors were well-designed, durable, & made plenty of horsepower. Obviously, the so-called " MX " was not built for the expert racers & rough motocross action but more for amateurs or " weekend warriors ". Full history about this exact motorcycle is not known but it appears to have been used as a rider and not a racer, It was found in Los Angeles California and proof of local use is verified by the " Green Stickie " on the left fork leg, Many such cycles were used until something broke and then parked for years before being rediscovered, Here pilot error filled the Autolube system with the wrong type of oil & the connecting-rod seized, A NOS crankshaft was located and the bike was resurrected into how one might have been modified in 1970 for TT scrambles or smooth track events. The narrow 21-inch front wheel was replaced with a 19-inch type & later style Dunlop track tires were mounted. The factory GYT head and exhaust were mated to a ported cylinder now fueled by a high-flowing spigot-mount Mikuni VM30SC carburetor, Carb is stamped with a 240 Code making it an original item from a Yamaha TD2 road racer. With the engine modifications and higher RPM capability an improved ignition was desired, While the motor was apart an internal rotor magneto from a 1972 Yamaha DT2-MX was adapted, Using the " button-rotor " eliminated any possibility of having the all-too-common Yamaha flywheel malfunctions and at the same time provided better performance, It's an excellent retrofit and the mag unit is NOS. The Autolube system and its related tank & plumbing was removed so that castor oils such as Blendzall Green or Blendzall Gold Label could be pre-mixed. Whether to use period correct tires like Pirelli / Carlisle or the modern Dunlop K180 was a toss-up, but for now new rubber won out. Either way is available.

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