Originally Posted by
xrayrc
should i be adding an extra .1 shim in the head for a 3port .21 sport engine to run 30% nitro? I have already ran 4 tanks of the breakin and the instructions said it was recommended to run 25 - 30 percent nitro. Have i messed up the engine or is it ok to add in the shim after 5 tanks of fuel?
The extra shim is just to help make break in easier. You can put it in now if you like...or leave it out. I would use it. I actually have left mine in my 5P and like it....seems to smooth it out a little.