Funny as soon as I saw it I screamed Dyno VFR but my old Dyno had different chain stays and no bottom gusset. On closer inspection it looks like an early 90's Diamondback Viper or Super Viper. Is there a stamp on the rear dropouts. For looks bent or reversed. I'd say a viper with the short top tube. Check out BMX museum those guys are really good. Give them several good pics you'll know within 24 hours.