Engine dies at takeoff

Over the last few rides my engine just quits as I let out the clutch for takeoff. Recently I changed from oil to ATF in the primary, so that's my first thought, but it doesn't seem to be slipping necessarily. I've tightened all connections on the carb and manifold to rule out a vacuum leak. I pulled the pilot jet and cleaned it. The bike starts and idles fine. The gears shift fine. Now I can't even get the clutch all the way out and it will die if I don't pull it back in. Any thoughts? Will the ATF cause that?

The ATF might cause it to release differently than what you were use to with the oil (although it should be minor difference). Try letting off the clutch slower or faster and see if there is a difference.

When you changed to ATF I assume you disassembled the primary and cleaned everything thoroughly?

I did clean everything well. It doesn't matter if I let out the clutch fast or very, very slowly, there appears to be a point right at the end of the friction zone where it dies out.

Did you change anything else aside from the oil? Ignition? Wiring? Carbs?

Does the bike 'feel' any different than before? If you are sure there are no vacuum leaks, do you what what the vacuum is on each manifold at idle? I would think at least 25 cm (10") of vacuum, and equal. Also, check to make sure your balance pipe (the hose connecting the manifolds) is secure and leak-free.

On the face of it, it sounds like you've got low vacuum.

Well, I think I may have it fixed (for now). It appears that I might have had a small vaccuum leak at the manifold and found my plugs were all carboned up as well (I think from too much time with the choke on), so I had a couple of issues. I haven't had the chance to really put the bike through its paces yet, since work rears its ugly head and it won't stop raining anyway. I guess the ATF isn't the issue, but I was figuring that the last thing I changed was the likeliest culprit. I may be asking for help again on this soon.....