The picco 21 is actually a "medium block." Still not sure about it fitting though. I'd stay away from the Fantom FR18. I have the 04 version and they recently discontinued all of it's parts. The crappy crankcase on mine snapped (just snapped) and now I can't track down a replacement. Nobody has them... I have a FR18 with 1 gallon on it and until I can find a case I can't run it. 160 bucks down the hatch. Toki engines are lacking compared to OS, SH, ect...