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2008 YZF-R125 (180cc)
537 Posts
yikes, not fun re the broken stud. been there before :-\.

Soak with wd40, overnight intitially (perhaps more than once) and then again thoroughly a bit before attempting to undo. Attempt to undo but with large Mole-grips or some big "channel lock" pliers. You're wanting max clamping force so whatever gives you the most/best grip. mole grips work pretty well for stuck studs normally.

If no joy with that then you'll probably need to apply heat (e.g. blowtorch) and try again. This would be difficult to do wiht the engine in the bike imho, and if doing so would probably want to be sure to remove thigns like the fuel tank etc before playing with blowtorches in that area.

The head is aluminium so you don't want too much heat on there, but you should be able to get the stud to glow a bit np. I'd do a bit more wd40 while it's still fairly hot and then try the mole-grips/pliers again. Once heated to glowing the end of stud will be softer too, so will probably deform so you basically want to clamp your mole grips as tight as you can so they cut into the threads and give you the best grip, as you may only have limited attempts at it.

Possibly also start by trying to wiggle the stuck stud both directions a little bit. Like if you get any movemement at all wiggling back and forth and more wd40 will normally get you more love than just going for it trying to undo.

If no joy with that you will either need to weld a nut on or drill it out. neither of which is fun or convenient.

Re the little air pipe on the exhaust you don't need it, so it's not a problem that it's missing off the other exhaust. But you will want to block off the hose on your bike which normally goes on there since it leads to the airbox and could perhaps mess with your fuelling if left uncapped (or has a cracked/disconnected hose.. which is common).

If you follow that hose back it leads to the airbox. You just need to block that hose off, either at the airbox or inline in the hose somewhere. If you can find a bolt or something suitable to shove in the end of that hose that would work just fine
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