Another runner joins the collection. I had always admired the design and engineering of this engine. Many years ago I purchased the drawings and hardware sets but only last year found a vacancy in the shop “schedule” to give it a go.
I followed the drawings for all things except a few material choices. The cylinders are aluminium with cast iron liners, the timing gears are anodised aluminium (modified, manufactured R/C car components) and the cooling shrouds are brass with an aluminium duct (instead of brass).
In the end, it all just went together as hoped. The only disappointment has to do with the powder coating on the shrouds that I “farmed out”. The shop messed up the first time by not coating the aluminium ducts for some weird reason. They kindly offered to re-do the job but instead of removing the first coat they laid another layer on top on overheated everything in the bargain. As a result the solder joints started to let go. They will either get removed, sandblasted and re-done or remain a reminder to not use that service again and get equipped to do it at home.
The undersides of the base plate is a busy place! There is the electric starter and its solenoid, fuel pump and its speed control, fuel tank, two ignition modules with coils, control switch panel and terminal strip. Usually I share an ignition control box between models but decided this one should be fully independent. Power is provided by a panel mounted Anderson connector (the starter will draw upwards of 30 Amps some something substantial is required).
The fuel pump is a peristaltic unit with a 12 volt DC motor. When I guessed at the pumping rate I over estimated and that led to making a DC motor speed control to slow it down. For those that aren’t aware, this design uses a pump to maintain a constant level in the small reservoir at carb level. Excess fuel drains back into the tank from the reservoir.
The ignition modules are to the Gede/Sage design. Thanks to those gentlemen for enabling access to such a nice, easy to use ignition controller. The coils are Ford “coil-on-plug” versions.
The starter is that used on the Chinese GY60 scooters. I did trim back some of the housing to make more shaft available for the 15 tooth belt gear. A 60 tooth gear for the crankshaft has a one-way bearing and a centre “adapter” that pins to the flywheel and keys to the bearing. That and a taper lock on the flywheel itself keeps it all snug.
Well … that turned into quite the ramble! Hope I didn’t overstay my welcome.
Oh ... the requisite video:
https://youtu.be/q-22bLM0HiE?si=itWwVeG11qeYXDL3