It looks like those Nord-Lock anti-vibration wedge-lock washers from Sweden came up very briefly in these Forums before my time, but I just thought I'd cross-post a swell little writeup on them that I stumbled across over on the
ADVRider Forums by a user named "rtwpaul" titled,
My Bike Rattles Itself Apart! What Can I Do?. There's a video there which explains all.
I wouldn't say they're exactly cheap, but at well under a buck a pop, depending on size and material (zinc coated or stainless), they're not gonna blow the kids' college fund either, for those who may want that little extra piece of mind. For your convenience,
here's a link to Nord-Lock's Amazon Store and their own website is at found at
www.nord-lock.com.
What with Royal Enfield's bizarrely eclectic mix of SAE and Metric, with maybe a
Whitworth fastener or three thrown in for traditional ultra-British gusto, it may be a bit of a challenge to sort out just what washers one needs, but there you have it.