1-3/4 is what the Manual states try take it another 1/4 (making it 2 full turns from being seated). This will enrich the mixture. When you messed with the A/F, did you also change the idle speed? This also could cause the stall out. After adjusting up to the 2 full turns, check the pipes to make sure that there isnt a bunch of black smoke. If this doesnt work and it continues to stall, adjust the A/F up slightly until it will stay running at idle. Take the bike on a short ride and when you return pull the spark plugs and make sure they are arent covered in black or dark brown deposits.
Hope this helps.
D.A.