Sharing my build of a 1976 Yamaha RD400 full race engine.
Techniques shown include engine assembly, measuring port timing, carb build, expansion chamber exhaust design and fabrication, dyno test and more.
The RD400 is a long stroke version of Yamaha's RD350 two stroke. The same tuning techniques can be used to build a RD350 race engine and exhaust.
This is not a full tutorial on everything involved with an engine build. It does not show final jetting or proper operation. Air cooled two strokes require precise jetting to allow full power available and not seizing or detonating the pistons. The life span of the pistons is short compared to a street engine.
Motorcycles are dangerous. It is the responsibility of the mechanic to build a safe engine. A blown up engine or oil leaked on a tire can cause a crash that may seriously injure the rider.
This video is backed up with decades of professional motorcycle mechanic experience. This is not a how-to video for a novice.
Viewing notes:
Click on the settings icon to playback at a faster speed.
Highlights:
0:06 Engine assembly
31:23 Measuring two stroke port timing
41:14 Ignition timing with PVL analog
41:46 Carburetor build
52:12 Exhaust design- expansion chamber
53:24 Exhaust fabrication
1:42:49 Dyno testing on Dynojet 250i