Originally Posted by aircap

So I adjusted all the valves, changed the oil and fiddled a little with the timing. The engine no longer makes the scary clackety sound, and the smoke out the tailpipe has diminished almost completely. (Just a puff when I first fire up the engine sometimes.)

It's getting better all the time.

Thanks again to everyone who posted in this thread. I appreciate all the advice more than I can say. I'll soon be posting a new thread or two regarding some other issues...but in the meantime, thanks, thanks, thanks.