Hi John.
Obviously there is no 'standard' setting for a carb - it depends on the engine it's fitted to and mine's unique. I tended to aim for Yamaha XT specs as the cyl heads I'm using are SR, but then my bore / stroke ratio is way different.
Anyway, I researched what others who fitted 34mm VM's to XT's had done, and I referred to those specs earlier. My out-of-the-box specs were close, but not exact. Indeed, even people with similar bikes use differing combinations.
Mine came with 15 pilot, needle jet P6, needle 6F9, main 175, air 2, slide2.
Changed pilot to 35, now 30. Changed main to 230 and changed slide to 2.7. Tried needle up, down and inbetween. It's presently OK idle to 1/4 throttle (needle down), but with needle up won't take half throttle - just bangs and farts. With needle down, it will rev higher, but really rough, hence my analysis that the larger pilot has enriched the needle circuit (remember all jets work together on these carbs). As I said, at £30 to change a jet in two carbs, I could spend thousands and still not get it right. Take the needles for example. Presuming the attachment comes out, you can see not only are there single and twin tapers, the needles in fact don't really have a taper - they have 6 different diameters along their length. Take 6F9 (mine) and compare with the supposedly richer 6DH4. But is it? The HD64 is richer at stages 5 and 6, but leaner at stage 2 and 3. How the hell can anyone get to grips with that mess? How many needles does an Amal have?
