http://www.bonzisports.com/faq.html
Q: What are the high/low settings for my carb?
A: Stock Walbro WT-644 carb
High = 1 1/2 turns
Low = 1 1/2 turns
Stock Walbro WT-603 carb
High = 1 1/2 turns
Low = 1 5/8 turns
Walbro WT-488 big bore carb
High = 1 1/8 turns
Low = 1 1/2 turns
Walbro WT-257 big bore carb
High = 1 1/8 turns
Low = 2 turns
Walbro WT-813 big bore carb
High = 1 1/2 turns
Low = 1 1/2 turns