Yamaha made these bikes specifically for 750 formula one racing. It’s a 4 cylinder water cooled 2 stroke. They were manufactured from 1974 thru 1978.
We validated the FIREPLUG CDI design by testing on a 1974 Model “A” TZ750 motorcycle.
The Yamaha part number is 409-85540-10-00 superseded to 1X2-85540-10-00. This is the same CDI part number for the TZ750 through the 1977 “D” model that was the “production” privateer race bike. The factory OW31 bikes may use the same ignition, but should be confirmed.
Hitachi part number is 11A04-02. It is possible the TZ500 also used this same CDI.
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