Got my first bike running and idling, but 2 of the cylinders will intermittently puff back through the carbs. It seems to only happen at idle and is maybe once every 15 seconds. I have done some of the main checks I have seen discussed on here but have not found anything conclusive. Here is what I have.
- KZ650 bored to 717
- 26mm Carbs off 900
- 115 main and 17.5 pilot jet
- Head was done by reputable tech, he did valve job and clearance (I didn't check his work)
- Carbs fully cleaned, float bowls set with clear tube
- Carbs bench sync then checked with vacuum gauge and all cylinders are 20 + or - 2 cm.wg
- Tried adjusting the idle air screws, started 1.5 turns out and adjusted slightly for highest idle rpm (I find it hard to hear a difference at middle adjustment, could only tell when the cylinder is bogging out when turned over 1 turn in or out from start point)
Any help would be great, this is all a first for me.