Tom,
If David put the motor together, you need to listen to him!
David, if you get a chance to look at the plug pictures, please let us know so I can make some time to put the other jets back in or not.
Tom,
For my own curiosity, could you tell us what the 770 came with from the factory and what jets you have in it now? I am not very familiar with that Avenger.
Note: If you put in a stiffer spring, that will delay the seconds. On my last carb (vac sec), I tested all of the springs right after each other starting with the lightest. As I put in stiffer springs, the motor had more torque off the line, except for the very stiffest. I ended up with the Brown one for my stock stroke 340.

Thanks