my tach needle just started resting on 2100 rpm when the bike is off or started and running under 2100 rpm. it appears to work fine as the rpm's go up over 2100, is this something I can take apart and clean or just nudge the needle back to rest on zero? I've tapped on the side and on the glass hoping to bump it loose, but no luck yet.
I take it this is an older bike.
The most probable cause is that the original needle lubricant was petroleum based. Being ancient and exposed to all sorts of temps and humidity levels, the lubricant has now oxidized, which filled the minuscule gap between the needle bush and needle pivot with a hard or gooey substance.
You can send the instrument to any BMW speedo repair shop, or local watch repair shop, and ask them to clean the pivot points and apply a silicone based lubricant made for watches.
Unless you work on watches, I would not attempt this repair yourself. View one of the watch repair videos on YouTube like this one and you'll get an idea of how delicate and tiny some of these parts and required tools are. And the amount of lubricant applied is like 1/100 of a drop.
Hope this helps.
Owning an old Airhead is easy.
Keeping an old Airhead running great is the true test.
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