Brakes and Throttle
Braking Systems and Throttle Control For Chopper
For this project we chose a disc brake for the rear. There are many different styles of brakes available: band, drum, and disc. Read here for more info on mini bike brakes.
The Disc Brake Installation
A parts supplier informed us that many people are using a disc brake without a dedicated braking disc, instead opting to use the drive sprocket as the disc. We decided to give it a shot (Fig. 1) and so far have had good results. It is worth noting that you should be careful of over-oiling the chain and getting excess oil on the sprocket, as this would hamper good braking response.
Hand Brake, or Foot Brake?
Both are adequate choices, and both are readily available from parts suppliers. We were looking for clean lines on the handlebars, and therefore went with a foot brake (Fig 2 &3).
If going this direction again, we'd run the cable through the frame. With a little planning it would be very easy, and give a further clean look to the frame.
To provide brake stops, we welded a small nut to a riser just before the foot pedal. This ensures that the cable sheathing can not pull itself forward.
The brake line was attached at the disc brake with common wire stops. We found that the easiest way to cut the sheathing and the wire line was with a cut-off grinding wheel.
Throttles are generally sold in 7/8" and 1" ID. This would work fine if you're using tubing, but because we wanted a bent handlebar, we had used pipe (OD = 1.05"). [Read more about tubing vs pipe].
Therefore we simply marked where the throttle assembly would end on the pipe, and ground down the material up to that point. (Fig 4). This isn't the most elegant solution because invariably you grind farther up the bar than intended and it will show after the installation. Perhaps using masking tape to make the edge would help.
The throttle cable runs from the grip back to the carb. We had removed the governor on the Briggs and Stratton engine, therefore we hooked it up to the throttle butterfly directly. This took a little engineering (Fig. 5).