The bike began making a terrible noise during an evening ride on Saturday. The sound was almost as if there was two pieces of tin metal rubbing against each other. At first I thought that maybe the headlight was coming loose or one of the pipes was rattling around. I pulled over and found nothing to be loose, so I continued riding but the noise persisted.

As I rode further, I found that the chattering noise amplified slightly whenever I would downshift or put the bike into 1st gear at a stop light. The bike has always made a very solid clunk when engaging gears, but it is now accompanied by a slight "screeching" or rattling.

Any thoughts? The bike is a 1974 Ironhead.

Thanks in advance for any comments or advice.

 

Maybe a loose chain sprocket off 4th gear (nut backing off)

 

When's the last time you checked the oil level in the transmision? Sounds like it needs more. What about while it's in neutral? I would stop riding it till you get it figured out.

Rich

 

From the description you give I would recommend you check the adjustment of your primary chain before you ride it any further.
If the primary chain is adjusted correctly, then try to locate the noise and go from there. Moving parts are what make noise. They are somewhere in or on the engine.
Do not ride the bike anymore until you locate the source of the noise and repair it as necessary.........pg

 

Pinion's advice is good, as usual. Also check your clutch hub bearings.