How do you avoid spark plug failure during a trial?

  1. Never leave your bike's fuel tap on when you are not riding.  This is especially important for the journey to a trial - the vibrations cause fuel to leak into the cylinder and wet the plug, and it becomes difficult or even impossible to start the bike.
  2. Use a new spark plug at the trial.  Nothing beats the ease of starting, the reluctance to stall, and the pure performance of a new spark plug.  Since plugs are about R35 each, it is worth it to have a new one every monthly trial.  One strategy is to fit a new plug for the trial, then swap it out

What oil/fuel mix should I use?

In a two-stroke trials bike, we generally use 15ml of two-stroke oil to 1l of petrol (i.e. in a 5 liter fuel can, add 75ml of oil, and in a 10l can add 150ml.

Follow the instructions in the bike's User Manual.

Also, be aware that not all two-stroke oils can operate at such low concentrations.  For example, Castrol Power1 Racing synthetic oil is not rated at such low concentrations.  I use Ravenol synthetic.  Be especially wary of cheap oils, but check whether an expensive oil is rated at 1:66 mix ratios.