Electric Moped Conversion

2008 Tomos ST, with a max speed of around 35 mph, 2 speed automatic transmission, and a whopping 1.3 HP. Before it came into my possession it had sat in a barn for around 8 years. An aftermarket exhaust was put on by the previous owner that made it deafeningly loud. In addition to the general grimey state of it, it had several constant mechanical issues that were a pain to maintain and the throttle sometimes got stuck open, which once caused me to crash it at speed.

A fairly common problem for this type of swing arm connection, the bearing around the connector bolt rusted and became seized. Although the swing arm could still move freely up and down, removal of the bolt to replace the swing arm was impossible. Pictured here is my attempt to heat up the bolt via blowtorch. An hour of this with repeated hammering from the other side proved unsuccessful, and I ended up having to cut the swing arm off with an angle grinder.

Although my moped model, the Tomos ST, did not come with a top tank, the Tomos Targa LX uses the same body in addition to a top tank. I purchased an old tank and marked it off for cutting. The goal being to use it at housing for the battery, motor controller, DC-DC converter, and all loose wires and connections. Also pictured here is the steel tube I will use to fabricate the new swing arm.

In order to house the battery and other electrical components, some modifications needed to be made. I cut the top of the tank off, roughly following the body lines to make the seams look natural. I then (painstakingly) cut out the inner U channel.

Once the channel was removed, I cleaned up all the burrs and sharp edges with a flapper disk. I then welded a piece of place steel in the bottom of the tank. This will be a floor for the components inside as well as a piece to mount the motor controller to from below. I then welded on a hinge to reconnect the top piece, while still being able to access the components inside for maintenance.