pakrodent

Hello, Just started here. I was needing some help on a 1975 Yamaha tx500 that has been sitting for 10+ years. A friend and I cleaned the carbs, the tank and was set to take it out. The idle sounded great, but when it was put into gear it was at half power with full choke and wanted to die. I pulled the top of carbs thinking that it wasn't getting enough air for fuel mixture. It seems that fuel is getting to both sides. Then I put my hand on the exhaust, the right side is firing warm but the left side was cold. I pulled the left plug and it was sparking a nice white/blue spark. My friend put a comprsion gage on it and it has the same compression on both sides. My question - now what? Any help or tips would be great. THANKS!