Originally posted by US_MATRIX
I just bought NS15S5 .15 engine and it has 0.4mm head shim.
I was wondering do i need to add 0.1mm shim ? I am running 20% fuel.
If your gonna run 20%, then one 0.4mm silver shim is good enough. If you plan on running 30%, then add the 0.1mm copper shim.