Header Pipe Nuts - why no lockwasher?

[Glaserbeam]

I replaced my exhaust system, installed new gaskets where the pipes meet the exhaust ports, and tightened the acorn nuts, but 1,000 miles later some of the nuts were loose and one was missing ... I snugged them up again (just as tight as they were with the original exhaust system) and a couple weeks later they were loose again.  This is frustrating since the nuts shouldn't be vibrating loose, and I don't want to overtighten anything and crush the gaskets or break a stud.  Why aren't lockwashers used with the acorn nuts?  Would it hurt anything to add them?

Still lovin' the Valk!

Ken

[Jess from VA]

With new gaskets, and a light 7 foot (or is it inch) pound torque setting for the header nuts, it is SOP to snug those nuts on install, and then at least twice more, after riding and heating them up.  Each time, compressing the gaskets more.   If you try to do it all at once, you'll likely snap a stud or two.

Using quarter inch sockets not only are easier to fit into tight spots, but also give a better feel when torquing (I don't use a torque wrench, just by feel).

I lost two acorns, and doubled up two standard nuts in replacement (both hidden unless under the bike).  I snugged the first, then used the second like a lock nut.  Anti seize is probably a good idea too.

[Chrisj CMA]

You waited 1000 miles to do the initial re-tightening, then two weeks for the next.
 
That is too long,  no wonder nuts were lost. 

Once you get the gaskets squished down they won't loosen up any more.

[MarkT]

I recommend tightening them twice, a week or so apart, and check again.  You can use loctite 242 (blue) to increase friction so they won't walk off.  But you'll still need to tighten them.  I too use 1/4" sockets.  On nuts 12mm & smaller.  Get a 10mm swivel socket for the header nuts.  Wobble drive extensions are also useful. On #5 cylinder back nut have to use 12 pnt box end. I keep one with the wall ground thin to fit.

[Houdini]

I don't want to overtighten anything and crush the gaskets

They're crush washers, you're supposed to crush them.

[Chrisj CMA]

I don't want to overtighten anything and crush the gaskets

They're crush washers, you're supposed to crush them.

I missed that lol. No wonder, trying not to crush them....

The sooner they get completely crushed the sooner the nuts will stay tight.

[da prez]

  Back to the original question. Lock washers on an exhaust system will rust off. This goes back to the days of installing brass nuts on the exhaust pipes at the headers to be able to get them off. Flat washers were used to prevent the problem. A flat washer will allow the nut to slide (reduce friction) as it is tightened. The lock washer would let water in a lot easier , and rust off.

                          TA  DAH
                                                          da prez

[h13man]

Anti-sieze and SS lock washers is an option and the re-torquing schedule as mention by others. As far as Loctite is concerned, I use heat to free Loctited fastners.

[John Schmidt]

I haven't had acorns on my header pipes almost from the first day I got the bike. Often you'll find acorns aren't deep enough to allow full tightening, so I simply converted to plain nuts/washers and move on. Never have had a nut come loose since, and if the looks of plain nuts bothers someone then explain to me why you're standing on your head to look at my bike. 

[Oldnick]

I haven't had acorns on my header pipes almost from the first day I got the bike. Often you'll find acorns aren't deep enough to allow full tightening, so I simply converted to plain nuts/washers and move on. Never have had a nut come loose since, and if the looks of plain nuts bothers someone then explain to me why you're standing on your head to look at my bike. 

HAHAHAHA! As I read your post I was starting to think just the same thing!

Nick