So on the recommendation of everyone here I pulled the head on my 04 CR250, followed the directions on RB-Designs webpage (had to buy thicker solder, .092 or so) and got three measurements. They all came out to .054 at the end of the solder. I'm not sure if I just got lucky, because most guys seem to report they have .070 or more stock. Previous owner may have had it done already, who knows? I emailed RB-Designs to ask what the ideal squish is but so far they just replied that they could help. I don't want to spend $100 for them to set the head to .050, which is almost nothing. Does anyone know what is ideal squish for 91 pump gas on these bikes? It's stock aside from pipe, VF3 reeds.