I assume that you have adjustable pushrods? If you do, try increasing the amount of preload - lengthen them. Some cams are super noisy with "stock" preload, and require a little to a LOT more.

Cheers!

 

I have attached a video where the noise is apparent.

Maybe it's just bad lifters?

 

Short video but I didn't hear anything alarming or out of the oridnary; actually that's a pretty quiet running motor. You might try more lifter preload per Clammy's suggestion but if it was mine, I would let it go and ride.

 

I can hear it with earphones.. Definitely sounds like one valve. I don't think it's cam gears.

When did you install the fancy valve covers? With a stethoscope you should be able to identify which valve is ticking.

You can try adjusting the pushrods to 0 lash and back off 1/4 turn. How does it sound then?

 

There actually were some tiny witness marks inside the valve covers, at the pushrod side of the rockers. I removed a bit of material and initially thought the noise was gone, but after riding a bit longer yesterday it was back. It only appears when the engine is really warmed up.
I have adjusted the pushrods to 5 full turns, that would be about 0.150" with 32 threads/inch if my calculation is right. S&S standard pushrods, not quick install.

One thing I noticed when adjusting the rods is that the lifters seem to bleed down quickly. All instructions I have seen says to wait 10-20 minutes before turning the engine, and to check if they spin freely.
When I adjusted I could spin them with my fingers after 2 minutes, does this indicate that the lifters bleed down to quickly?

 

What annoys me is that when the engine is cold it runs really quiet, it sounds really good.

But after maybe 30 minutes of riding I get this clattering noise, that I think is most noticeable on the left side of the engine.

It sounds very much like an old car that needs to have the valve lash adjusted, which is why I am more and more suspecting one or more of the lifters is bad.

 

So that's the original lifters you installed with the cams, if your going to replace them, take some time to measure the lifter bores, you may be abled to fit some +.001" or maybe even .0015" oversize.
I had a similar issue with lifter noise, tried some Johnson-Hylift slow bleed down w/limiters, still made noise when hot, pulled them right out and saved them for later use. (those are now in my stock M8 bike with the limiters removed, which stopped the M8 cold start lifter rattle)
I carefully measured the lifter bores and was able to use the Fueling +.0015" short travel race series lifters, short travel is not absolutely necessary, but I like using them or limiters in other lifters with performance cams.
Fueling gives the size range the oversize lifters should measure. https://www.feulingparts.com/category/Lifters
I had to "prep" them as in my previous post, to drop them in without scratching the lifter bores, the lifter noise has not returned (yet, fingers crossed). Running S&S 585's cams.

Different brands of lifters measure different, I had some S&S and Johnsons standard size lifters on the bench and the S&S's where .001" smaller, with a maximum lifter to bore clearance of .0026", .001"can put it over, minimum is .0009", .0005" wouldn't scare me, the clearance grow with heat.
I always measure lifters and bores and match the largest lifters to the largest bores, every little bit helps and cost nothing.

 

Thats interesting, thanks for the info.

How do you measure the lifter bores?

 

I use a telescoping gauge and a mic, set the size with the mic and use it as a go-nogo gauge.

 

Is this just as an experiment, or could I actually run the bike like that, long term?

Thanks for the info