Ok, I've seen this topic tossed around on a few boards in the past but I thought I'd bring it up again see if there are any fresh ideas or new attempts; The Sudco tuning manual says that Bleed type Needle Jets are for 4 strokes and Primary Type are for 2 strokes. I just got a VM36 for my XT500 and (like many after market carbs) it comes with a primary (type 159) needle jet. The stock carb was bleed type but it turns out most people with after market VM carbs are running primaries in their 4 strokes... Now in theory the design of a Bleed type needle jet would provide better fuel atomization and this is of interest to me... The 176 bleed jets fit VM carbs and Once I get this carb dialed in I may try to dial it in again with a bleed type needle jet. Anybody ever try this?