Engine dies at 3k rpms

[cvcsmkr]

98 sportster twin 717's

Carb recently rebuilt
switched to premix

If i punch it, as soon as it hits 2750 it will completely die, if i let it sit at 2500~ for a few seconds and slowly accelerate it will get to 6500 and runs great then.

Also if its been idling for a few minutes and i give it throttle, it will die.

Does the carb need tuning? If so should i adjust the low speed mixture?

 

[Dr Honda]

Sounds like the check valve on the main jet is leaking back.

When it leaks, the pilot jet will draw air though it, and drain the diaphragm, So... when you jump on it, there isn't any fuel in the main circuit. If you bring it up to 2500 rpms... it can re-fill.

The other thing is that your needle arm is well below the carb body.

Regardless, you need to take the carbs apart.