Kinda Interesting Carb Video, FIXED already, odd problem, solution in bold. Options

[McMark]

Trying to trouble shoot an acceleration lean problem on this set of carbs. So we stuck the GoPro on the back and took a quick test drive. Video confirmed that the pump doesn't squirt as readily/quickly as it should. Still working out the solution, but thought I'd share the video since it's mildly interesting.


https://www.youtube.com/watch?v=XYDmTkNTk3w

[McMark]

Not a plugged idle jet. Runs perfectly at idle and cruise and as long as you don't punch the throttle.

Actually, if you look really close on the HD version in fullscreen you can see the problem. The accell pump squirters don't spray immediately. There is a lag. So when you open the throttle, it goes way lean until the pump finally kicks in and richens things up. There is a tiny check valve in the bottom of the bowl with a ball inside. I compared these 'new' ones with some old IDF pieces and the new ones have a lot more slop. This was also proven by blowing compressed air backwards against the ball. It took half a second for the ball to overcome inertia and move into place, blocking the flow of fuel. This meant that there was half a second of fuel dumping back into the bowl before the ball finally sealed and starting dumping that fuel where it was supposed to go.

Here's how I fixed it - These accel pump check valves have a little plate in them to limit the movement of the check-ball, so I simply tapped the limiting plate closer, moving the ball closer to the seat and reducing the amount of flow necessary to close off the passage. Yes, I thought about making sure not to restrict the flow of fuel overall. But this modification and going one step bigger on the idle jets solved the hesitation.