Hey, sorry if this is a really stupid question but what is this nut around the exhaust called and how do I safely remove it? I've searched on google for ages and can't find what sort of tool this would need, I'm willing to order the proper tool

+1 to Mauser's reply.

What bike is it off?

Oh, and there's no such thing as a stupid question!

Tool is called an "Exhaust ring nut wrench" or generically a "hook spanner".

I have a universal one that works... (Check on Amazon... make sure you get one the right size for the diameter) I've never seen a Yamaha one except in a catalog (see pics). You might search ebay for an original.

Way back when we always used to use a hammer and punch to loosen and tighten.... but if really stuck you could break the threaded flange off the cylinder if hit too hard.

That is rusted up pretty good.... might need a lot of penetrating oil and heat no matter what method you use.





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Mauser posted a great possibility while I was typing and getting pics...

FS1E is similar to small Yamaha enduro engines....


Amazon has this set... or you can find them individually.

www.amazon.com/ABN-Adjustable-Hook-Wrenc.../140-7228947-5659306

I've always used an appropriately sized piece of bar stock and a Big.....Hammer. (BFH) After soaking it good with penetrating oil you place the bar stock against one of the notches and give it a whack with the hammer. Make sure your spinning it off, not on. By the looks of that nut, I may have already worked on that bike. Lol

As Schu said, I would keep it wet with a good penatraiting oil for a few days first and while keeping it wet, use a small hammer (SFH) and lightly tap around the OD to help break up and break loose the rust. It looks like there's a lot of rust. You'll need the BFH for enough impact to get it moving.

Use caution with a BFH... cylinder is cast iron and you can break the exhaust fitting off easier than you think it might happen. Don't ask how I know.

Suggest some heat with a heat gun or propane torch several times over a period of days with lots of penetrating oil before you apply any force.

All good words of caution. In lieu of using any size FH, I have more recently used my air chisel and a long 3/8 extension. I place the male end of the extension against the nut flange and insert a blunt point chisel on my air hammer into the female end of the extension. One short braap with the air chisel and it typically spins free. Not sure if that method is less likely or more likely to fracture the cast iron cylinder flange. Proceed at your own risk. One mans braap is another mans Oh Sheet.

It's off a 79 GT80. Thanks so much for the ideas guys I've had penetrating oil sitting on it for a couple days now. I've tried giving it some hits with with a hammer and punch but I'm too afraid of breaking anything to have given it a good enough smack to accomplish anything yet. going to try heating it up a bit with a torch as well after I watch a little video to make sure I do it properly. Going to test the fitment of few pipe wrenches I got lent to me.