This video shows what is involved in upgrading from a DA-100L engine to the new DA-120, 120-cc engine from Desert Aircraft. Due to the lighter weight of the engine and its shorter nose vs. the DA-100L, it was spaced forward an additional 1/4", and one of the A123 Rx packs was much further forward. Having up to 60 lb thrust on a 29 lb flying weight makes the Yak fly like a giant foamy! The engine performs perfectly and after trying various props, the Mejzlik 28X12 was our favorite - as it combined ballistic speed, strong punch out of a hover, and amazing rate of climb in a vertical.