JD37 - The powerfull 37cc

My biggest challenge to start this project, was gathering of information about this engine and its peculiarities…

There is not a lot information on the internet about him, it was produced to Brazilian factory called Hatsuta Industrial S.A and his model is JD37.

                                      

It has a 37cc displacement and 1hp at 7500rpm, it’s a elementary two stroke engine (similar a used in a grass cutting machine) and its used in a vehicle called Walk Machine (a success vehicle in the 1980s was created to transport and to amuse children and adults, similar a small motorcycle).

The JD37 has a original ignition system using a contact breaker (first version of this engine, but the newest version use a Capacitor Discharger Ignition System and don´t needed a contact breaker, only a high inductance coil), it does not have ignition timing compensation through load, engine temperature, I have a conjecture that this ignition timing curve is not opymized for this engine, because in Brazil this CDI is applied in other engines that have totally diferent characteristcs, biggest displacement, other geometria, his never works optimized…

The main characteristic I desired improve with the advent of my new project was a possibility to map the ignition timing angle, because in my analysis its the best way to get better combustion efficiency and optimize for all engine speed, engine temperature, load that works (facility to crank, more stable in Idle and fast response when desired), other important consequence is increase the rpm, this way increase the top speed.

PS: My engine has a exhaustion system and air filter different the first figure, it is like the picture above (old version)!