Tecumseh tvt691 2001

i have a tvt691 from 2001 twin carbs, popping back through cyl 1  carb, i have changed and gapped the plugs, changed and gapped the coil, readjusted the valves. all of this has slightly improved the problem but i am still popping back through carb#1 and am low on power. I have also bypassed all of the safety switches. any ideas????

Thanks, i will do a leak down test

you were correct, i had  a sticking valve, a lot of carbon buildup and carbs need to be cleaned again due to a loss of topend power.
 
Thanks for your help