How can I figure out what's making the clunk in my 1981 650 Maxim?

My bike makes a weird clunk sound sometimes. It's coming from the front end somewhere. It mostly happens the first time I take off for the day, but the other day it happened while it was still warming up in N. Some days I get lucky and there's no clunk. . It's my first bike, and the first thing I ever wrenched on besides small engine repair class in high school. I've tried to record it but it didn't happen when I was recording.
Is it something I should be concerned about, either damaging things or locking up while I'm riding?
I'm planning on just kind of waiting until it's too cold to ride this fall to do any more major work to it.
What do I have to do to figure out where its coming from?

 

Parts 4 and 5 engaging. Rev the engine in neutral until you hear it. My 900f does the same all the shaft drive bikes do. Nothing to worry about.

https://www.cmsnl.com/yamaha-xj650-maxim-1981-b-usa_model8822/partslist/C-06.html

 

The spring pushing these parts together is making the noise.

 

I always get good answers on this forum. Thank you.

 

I'm in agreement with Franz, I had the exact same bike and it does what you describe. Since there is no cush drive in the rear hub like most chain drive bikes, there is the spring loaded middle gear to absorb the shock. It does make a good clunk, easy to reproduce if you get on the throttle hard on take off or down shifting. Nothing to worry about there but you do mention it sounds like the front end, can you elaborate more? Would like to rule out anything else before we write it off as the usual clunk.

 

To elaborate on the "front end" it sounds like its closer to my toes, not near the rear wheal or final drive.

 

This is a photograph from the Haynes manual of it being installed.





You can see the shock absorbing parts held together with the spring in the photographs.

 

The spring loaded middle gear jayrodoh referred too does the same job as the four springs on a car clutch friction plate as mentioned to absorb the shock. Put the bike on the centre stand, start it and rev the engine. Then intermittently you should hear the noise as this will eliminate the noise possibly coming from the front of the bike. I put a mechanics stethoscope on the crankcase top behind and in line with the starter motor to check it. Sometimes it is difficult to pinpoint exactly where the noise is coming from.

 

I'm pretty well convinced that's what it is.

 

I was looking for a video l had of the noise on my machine so you could compare it but unfortunately cannot find it. Nothing to worry about.