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Improve the RD 350 Yamaha
To put "racer" in the cafe-racer theme, I wanted to increase the go instead of focusing on the show. Since I found out that the bike is running pretty decent I postponed my idea to do a full engine rebuild. This gives me the time to source a second set of cylinders and heads since mine has cracked and missing cooling fins.
Warning, longest post jet!
When looking at the package there are 3 obvious areas to improve:
- Ditching the points ignition for a CDI with a curve
- Improve the breathing of the bike (the stock airbox is very restrictive)
- Add Expansion chambers, for looks, sound, and performance.
Ignition upgrade RD 350 Yamaha
So I started doing internet research on what ignition alternatives were available. I quickly learned that it's not easy to retrofit a Yamaha RD350 LC or banshee ignition. the player's in the market I found were:
- VAPE
- HPI
- Dyna
- Powerdynamo
- Newtronics
- Adapt a Zeeltronic or Ignitech
In the past, I ran an HPI-programmable ignition on one of my projects and I had a lot of issues with the stator frying itself. The Dyna and Newtronics, just swap out the points for either Hall-sensors or light-ports, keeping timing fixed. Vape and Powerdynamo offer a complete swap, with a new stator & flywheel combo which eliminates the need for a battery and has a CDI with a timing curve that fits the RD. Many people rave about the quality. For me they both have a major drawback, it runs from only one ignition coil (with 2 leads) as the RD runs with a 180deg firing interval it has to run with a wasted spark (sparkplug firing in BDP also) which could become a problem in the future if I want to run higher RPM's than 9K. Because the coil fires twice per revolution the dwell-time or charging time of the coil drops, lowering the spark energy. Only the zeeltroninc or ignitech could fix that, but they would need a lot of adaptation and are by far more expensive. Also, they include provisions for controlling YPVS valves and power-jet's I do not intend to run either one on an air-cooled RD.
Fortunately, I found "Bert van de Zand" on Facebook, and he was looking for specific projects to complete, he quoted me a reasonable price (lower than the VAPE) for a digital CDI ignition running of hall sensors with dual coils and electronic rev counter. In order to fit this to my RD, I made a timing flywheel, pick-up plate and coil mounts. Once fitted it ran almost straight up OK, the only real issue I had was that the old battery a mechanical voltage regulator couldn't keep up with the iginition causing voltage drops and ignition cuts. This was solved with a new battery and electronic (yambits) regulator (and properly sized feed wires with a hard ground).
Breathing
Getting fresh air and mixture in, with the standard airbox it's too restrictive. Probably to reduce intake noise. During one of my late-night internet strolls I found that keeping the Y-booth is sensible, just adding a K&N cone filter per carburetor was making tuning difficult due to unwanted reflections. I toyed with the idea of making a small Glassfiber airbox and fitting a big (banshee) pod filter to this, but I couldn't find room enough for that as I needed to keep the battery. I briefly tried to fit an Alfa Romeo twin carb oval-shaped filter but was struggling for room. So I opted to run a LARGE K&N cone from the standard Y-booth. The intention was to install YPVS intake manifolds with crossover tubes and YZ85 Membranes, but I needed to modify the cylinders too much for that. So the membrane and manifold swap have to wait until I revise the engine.
