Scary ratcheting sound when I release clutch to first!

[mupheyslaw650]

So I finally got my '79 special running and started my test rides. Earlier today I was riding around town and got the idea to see how fast i could start out (I know I shouldn't but I found a safe straight road with no traffic to do some drag starts), so I rev up to about 4k rpm ( I didn't want to press my luck too much), release, and immediately I get this very loud ratcheting clanky sound coming from my engine. It only lasts a couple of seconds if I stay on the throttle or it will stop if I let off the throttle. It does not happen if I start out slow and then gun it. This is the only event in which I have encountered any such problem as well. I just rebuilt my clutch but I highly doubt this could be coming from the clutch though. I would really like to get on a drag track to smoke the my friend's cars which they think are "all that and more" but cannot until this is fixed :'( Does anyone have an idea of what this could be?

 

[jayel]

chain jumping the sprockets, broken cush springs in the clutch hub, loose nut behind the handlebars

 

[mupheyslaw650]

Jumping the sprocket must be it. Rear sprocket teeth are broken like hell, I forgot to re-tighten the new chain

 

[maynard911]

If the sprocket is so worn that the chain is jumping you can be sure the life of your new chain will be measured in hours not years. Even a very loose chain will not jump on good sprockets. Get some new sprockets, it will save money in the long run.