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Converting a DS-7 roadbike into a TD 3 racer special.
There are a number of similarities between the DS-7 roadbike and the TD3 production roadracer which allow the roadster to be converted into a competitive racer. In 1972 Yamaha released a bulletin on how to complete this conversion. Below is essentially a transcript of that bulletin. Please note, a few of the parts mentioned are no longer available through Yamaha.
Please check the part numbers with your supplier before attempting to order.
A fine example of a DS-7 converted to a TD-3 roadracer.
Model: . . . . . TD 3 (DS 7 Engine Used)
Displacement. . 247cc
Bore and Stroke: 54 x 54mrn
Number of Cylinders: 2
Use: . . . . . . . . . Road Racer, Drag Racer and Half Miler
Cylinder Head Volume: . . . . . . . . . 10.2cc (Part No. 239‑11111‑00‑00)
Carburettor Size: . . . . . . . . VM 34 SC (Part No. 329‑14101‑00‑00)
Ignition Timing: . . . . . 2.0mm BTDC
Spark Plug Heat Range: . . . . . . NGK B 10 EN
Special Parts: (Road Racer only)
Rods: . . . . . . . . . TD 3, Slotted (Part No. 328‑11650‑09‑00)
Bearings: . . . . . . . Small end (Part No. 93310‑21636‑00)
Big end (Silver cage) . . . (Part No. 93310‑42255‑00)
Crankshaft Main Bearings (Special)
Tacho Idler Gear Set: (Bearing: Part No. 93310‑21564‑00)
(Gear: Part No. 328‑15650‑00‑00)
(Washers ‑ two each: Part No. 328‑15653‑00‑00)
(All tacho idler gear parts above must be installed as a set.)
Ignition System: . . . . . . CDI Magneto Assembly (Part No. 328‑8500‑10‑00)
Ignition Coil ‑ two each (Part No. 328‑82310‑60‑00)
CD1 Unit Assembly (Part No. 328‑85540‑10‑00)
Clutch: . . . . . . . . . Exposed, dry type (Part No. 328‑16301‑10‑00)
Clutch Primary Gear (Part No. 328 - 16150 - 10 - 00) Use this gear with dry clutch only.
Covered, wet type (Part No. 329‑16301‑00‑00)
Clutch Primary Gear (Part No. 328 - 16111 - 10 - 00) Use this gear with wet clutch only.
Transmission: . . . . TD3 Close Ratio transmission is available in 5 or 6 speed.
Transmission Shaft is a special for the dry clutch if used.
Expansion Chambers: . . . . TD3 Left side: (Part No. 329‑14610‑00‑00)
Right side: (Part No. 329‑14620‑00‑00)
Optional Equipment:
Chassis: TD 3 Frame: (Part No. 328‑21110‑00‑33)
Swing Arm: (Part No. 239‑22110‑00‑33)
Wheels: TD 3 28‑inch Alloy Rims
Brakes: TD 3 Drum Type: Four Leading Shoes ‑ Front
One Leading, One Trailing ‑ Rear
Fuel Tank Assembly: . . . . . (Part No. 328‑24110‑00‑00)
Front Forks Assembly . . . . (Part No. 328‑23100‑00‑00)
Fairing Assembly: . . . . . (Part No. 328‑28350‑00‑02)
Note: When using TD 3 parts in a DS 7 engine, be sure to check parts book for interchangeability. Many individual parts are not interchangeable, and must be ordered and used as sets.
Cylinders:
TD3 Roadrace cylinders used: Left side: (Part No. 329-11311-00-00)
Right side: (Part No. 329-11321-00-00)
All dimensions are in millimeters.
Tolerance: ± 0.5mm
Pistons:
TD3 Roadrace pistons used: (Part No. 329-11631-00-96,97, 98 or 99)
Expansion Chambers:
TD3 Roadrace expansion chambers used: Left side: (Part No. 329-14610-00-00)
Right side: (Part No. 329-14620-00-00)
Material thickness 1.0mm
All dimensions in millimetres.
Tolerance ± 1.0mm
03/23/08 07:15 AM +1000
This website © Greg Bennett 2002.
