Exhaust stud stuck, no thread left to put two nuts on

Hi,

Topic title says it all. My exhaust is leaky because one of the studs is completely gone, there's no thread left. That also means I can't get two nuts on there to extract it. I was thinking of maybe doing either of these:

1. Drill a hole and hammer in a torx bit
2. Attempt to shape it off so a socket wrench fits on there

What are your thoughts?

Thread on one nut, leaving the nut proud of the stud, and weld it to the stud from inside the nut. The heat will help with removal.

Agree about welding on a nut. And watch how much torque you are placing on the stud when the time comes to turn it out. If it's not coming out as expected heat the stud and use lots of penetrating oil. Take your time or the stud may break off.

Be careful with the torque. the head casting has been known to break off where the stud threads in.

Whatever you decide to do it would be WISE to soak the fastener for 3 days with Kroil. Kroil definitely will help break the bond between the steel stud and the aluminum cylinder head. Ed

A big thumbs up on the combination of Kroil and heat! Also very good advice about limiting the amount of force applied, before it turns into how to remove a broken drill bit or easy out.
After rereading the O.P. I see there are NO threads on the stud. Kroil, heat, vice-grip, and patience.
Good Luck! Mike

Thanks a lot for all the advice and replies. I forgot to mention in my original post that I had already tried welding (be it with the max voltage for the most heat), but it seems like the studs are stainless steel. I don't know a lot about welding yet, but stainless steel just won't attach to my welds at all.

Couple of questions:
1. I've already soaked the stud in a lot of WD40, is that a lot different from the suggested KROIL?
2. How about my two idea's from the original post, since welding is not going to work. What do you guys think of either of these?
3. How about a vice grip, like Mike suggested? I didn't actually try that yet because I've lost mine, but I can get a new one and try that, before re-shaping or drilling into the stud, potentially breaking it?

Forget about shaping the bolt or the Torx business. You won't be able to get enough torque on the stud to remove it.

WD-40 is a crappy penetrating lube. Get something better. Heat the stud red hot with a torch and tap the end with a hammer to interrupt the chemical bond of corrosion. Vice grips may work but if they slip to easily you might have to find someone with a better welder.

1st. - WD40 is for the Kitchen junk drawer! It's 40% water. Household use!
2nd. ??? What Sickle? Engine? Stud Size? 6mm? 8mm?
Exhaust still On? Off?
Yes! On a good professional penetrant. Get a (real) quality pair of vise grips! A pair with the tip that has something that bites! Not from the Chi-Comm Tool Store either!
Lock it on remaining stud, flush up against the aluminum head, as tight as you can! That type of squeeze that hurts your hand when it locks tight and vibrates through your hand and you say ouch! That hurt! At a good angle of course!
And a little propane torch heat! Heat the aluminum head slowly around outer diameter. Don't need to heat stud.
Then if you can't unscrew it that way! We are coming to take your motorcycle away from you! Just Because! Just Sayin'

You got a lot of good information here. Kroil is my go to penetrant for these situations. It must be allowed to soak in for a few days on something that is really "stuck". As also suggested heat the area around the stud but try to stay away from the stud itself. You want the head to expand not the stud so much. Lastly, while the Kroil is doing its job, if you can take a small hammer and tap on the stud to shock it a little and help the Kroil work it. Don't beat the stud into submission, just tap on it occasionally during the soak-in time.
Rick H.

The reason to heat the stud is to break the corrosion. Don't turn the stud while it's hot, just heat it good and hot and let it cool. And with regards to tapping the stud with a hammer, be sure to tap it on the end, like a nail. Don't tap is sideways or it will bend.

This is a sreen shot of a Z1 service bulletin. Appears vice grips are a factory approved stud removal tool. :woohoo: