God awful banging noise

[Swinborg]

On shake down run I kept hearing a really loud metalic banging noise, I figured on side stand, if so why as string seems to keep in place???

Anything else I may of missed???

[Pluggy]

There are bolts, two on each side (at the passenger pegs) that hold the mufflers on.  If these get loose the muffler assembly will be banging up and down on the loose bolts.  On a ride, I couldn't figure it out.  Got home and found one had fallen out on my return trip and one was loose. 

I had never touched those bolts and the threadlocker was still on the loose one from when it was new.

[Chrisj CMA]

Failed u-joint can bang real good too.

[Jess from VA]

God awful banging noise

That happened to me a couple nights in cheap motels.  On and on, and yelling and appeals to deity.   
 

Seriously, a bit more description of the noise would help.  Is it motor, or other?

[Swinborg]

How do I check for a failed U joint?

[The emperor has no clothes]

How do I check for a failed U joint?

You need to take it out. I wouldn’t bother at this point. It’s a pain to get the boot back on. If the ujoint failed enough to make that much noise, you’d be feeling massive vibrations.

[hubcapsc]

How do I check for a failed U joint?

Remove the wheel and the final drive and shaft.
This write up has lots of pictures: http://www.valkyrieriders.com/shoptalk/rear_end_service.pptx
The wheel and final drive are the easy part. When they're gone you can get
the u-joint out from behind that accordion boot you can see up in there past
the right footpeg.



-Mike

[Avanti]

If I just picked up a new to me Valkyrie I would pull the final drive out and do a complete rear drive train service even if I was told it was just done.

[Jess from VA]

When my Ujoint went, I got thumping in my pegs (and grinding, limping home).

When my wheel bearing went out (the infamous single row in back, later changed to double row), it was grinding, squawking, squealing.  I got about 20 miles to a shop, discovering the least amount of noise was about 32mph rolling along.

Short of removal and inspection, if home, you can take the bike for a neighborhood spin, and do some very gentle throttle blip and releases in first gear.  All shaft bikes necessarily have some play in the drive train, but a failing Ujoint should be felt with peg thumps and sounds and maybe some grinding under load.

As soon as I replaced it, I got another spare.  Same deal with wheel bearings, brake pads, oil filters and and a battery with acid on the side.

A lot of guys ordering a new Ujoint also get a new boot, on the theory that new ones are easier to get back on than old ones.  Maybe so, they're all a bitch to get back on.  And don't poke a hole in it with a tool trying to get it on, that lets water in and down the driveline.  A small hole can be repaired with liquid electrical tape (don't ask how I know).  The trick with the boot, and shaft is having the swingarm about perfectly level when working. 

Here's a nice link on the Ujoint.  Click on each picture for more detail.
https://web.archive.org/web/20160523032210/http://www.rattlebars.com/mtz/ujoint.html

[Swinborg]

SOLVED,

it was the lower bolts on the exhaust brackets.  They were torqued up, but in a surprisingly short period of time vibed free.  Cured with thread lock.