I like how Don from the North American Two Stroke forum refers to this acid, "Two Stroke Hone = Muriatic Acid". Muriatic acid can be used to remove aluminum deposits left on the nikasil plating after a piston seizure or any other engine damage. The process is very easy and straight forward and it only takes a few minutes.
You will need the following
a) Muriatic acid (obviously),
b) chemical resistant disposable gloves
c) and a couple cotton swabs.
Let's start with the cylinder. This one is from a Cagiva Mito 125cc bike that had a piston seizure in the past. There are a lot of piston deposits on the left hand side of the exhaust port that we need to remove.
Carefully dip the swab in the muriatic acid and gently rub the nikasil plating all over the damaged area of the cylinder. In a few seconds the piston deposits will react with the muriatic acid and start removing easily from the cylinder surface in a liquid form. Be careful that muriatic acid does not drip to the exhaust-transfer ports! Rub the area with wiping paper or a cloth and repeat the process a couple times if you need to. In the photo you can see a radical improvement on the cylinder surface and looks much cleaner.
Obviously the advantage of the muriatic acid is that it does not react at all with the nikasil plating and only removes the aluminum deposits.
Here is a better view after the process is complete that only took a few minutes. In the next article I will show the next step and that is cylinder honing.