Engine Rework Update
So, there has been quite a bit or work that's happened over the last many months, although with much varied intensity, i.e. not much intensity at all at times. After the last piston failure, we decided to do a more thorough overall of many of the parts inherited from when we purchased it a couple of years ago.
|Close ratio gearbox from TZ-350 and dry clutch||Unchanged|
|Mikuni VM carburettors||Keihin PWK 35 mm|
|Standard barrels||Re-lined and mildly ported|
|TZ-750 pistons||Vertex Yamaha Blaster piston, 66.5 mm|
|TZ-350 roller bearing crank, standard stroke||Hotrod +4 mm crank with 115 mm rods (to be rebalanced)|
|TZ-350 water pump||Electric water pump|
|Standard RD-350 generator||Custom engineered lightweight race generator and lightweight flywheel|
The objectives of this "rebuild" was:
- Give it a "mild tune"
- Achieve a modest increase in horsepower
- Reduce engine vibrations
- Reduce engine weight and moreover width
So, what have we done so far:
- We changed the water pump to electric one and removed the mechanical water pump and drive
- We mildly ported the barrels
- We purchased a +4 mm stroke Hotrod crank
- We purchased light-weight Yamaha Blaster piston from Vertex. Previously, the engine was bored to 66.3 mm (TZ-750 pistons) and the only RD-350 pistons available in that size are Mitaka ones, which are pretty heavy. Plus, the higher pin height of the Blaster pistons eliminates the barrel spacers usually required when installing a stroker crank with the long rods.
- Modified head gasket to 66.5 mm diameter.
- Modified standard head for better squish and head volume
- Performed engine balance simulation to determine necessary modifications
We'll detail the individual items in separate blog posts. The first one we'll detail will be the balancing work we're doing on the crankshaft.