An odd Rattle...

Video, poor mic on the phone can't hold up to that much noise.

Was the Idle that high before you did the Points replacement?
Hard to tell on the noise, EX is Loud, and the Mic is getting that instead.
It sounds like it is really struggling with the starter, hows the Kicker? Hard to Kick it? Stiff?
Is so Turn the ignition off and kick it, any better?

That's the idle while choked. Normally around high 3k. When warmed up 1500 to 2k is the norm. Anything less than 1500 and it stalls.

Robwolf wrote: "You should get into the habit of using a torque wrench when working on your bike"

I probably should. I need to make the investment in some good tools.

This investment is very valuable for future investment.

Would check the timing advancer and assure that it's functioning properly.

Good Fortune!

Remember though, the trouble only begins after the bike reaches higher temperatures. I'd say after about 10-15minutes of riding, less if accelerating hard or riding at highway speeds. Could the oil be gunked up, or maybe not getting to all the parts in the engine, causing the poor thing to overheat?

Have you checked the valve clearances? Thats easy to do on the twins.

Motor Head wrote: Have you checked the valve clearances? Thats easy to do on the twins.

Right, adjust the valves before you do anything else.

Adjusted valves to be ~.2mm. Adjusted point gap to where it belongs, advanced timing slightly. Checked timing chain tension and adjusted it. Changed the oil. Fired up, ran loud and normal for a few seconds, and then that evil rattle returned. Its pretty fast paced, matches the RPMs and sounds something like metal on metal clinking. It got louder earlier today. I'm beginning to thing that something is broken or loose inside the engine. Tomorrow I will pull the side cover off where the magneto is and take a look in there. The sound is coming from the left side, but I can't tell if its down near the bottom or up near the top. I seem to have exhausted most of the options involving the upper end and timing and may now need to look lower. *SIGH*

Robwolf wrote: Adjusted valves to be ~.2mm. Adjusted point gap to where it belongs, advanced timing slightly. Checked timing chain tension and adjusted it. Changed the oil. Fired up, ran loud and normal for a few seconds, and then that evil rattle returned. Its pretty fast paced, matches the RPMs and sounds something like metal on metal clinking. It got louder earlier today. I'm beginning to thing that something is broken or loose inside the engine. Tomorrow I will pull the side cover off where the magneto is and take a look in there. The sound is coming from the left side, but I can't tell if its down near the bottom or up near the top. I seem to have exhausted most of the options involving the upper end and timing and may now need to look lower. *SIGH*

Might find a loosened bolt in the generator area.

Here's another source for info and trouble-shooting.

www.armbell.com/forum/index.php?c=6&sid=...571a51a&mforum=kz400

www.kz400.com/

Good Fortune!

Robwolf wrote: ........... The sound is coming from the left side, but I can't tell if its down near the bottom or up near the top. I........

Try using the crude but effective mechanics stethescope - a long screwdriver with a good solid plastic handle. Put the blade of the screwdriver against the suspect part of the motor and hold the handle right against your ear. That should help find where exactly the noise is coming from

I've been using KZ400 a lot. Hell used it before I even picked up the bike. THe other one I haven't seen yet, have to check it out.