Exhaust studs

[Tat2demon]

Working on a friends bike and I needed to pull the exhaust off. First stud broke off.

Obviously to fix that one I had to keep going and three more broke off. 3 of them broke right behind the nuts and one flush with the head.

Ive been soaking them all in PB for the last 4 hours but they wont budge with a vice grips.

I just tried drilling the one that broke flush and using an extractor on it. The extractor snapped in half and now I have a chunk of hardened steel stuck in there. Tried to drill that out with a cobalt bit and it chewed the end of the bit apart. Any ideas?

[jwhughes3]

New head.


John

[IanDMacDonald]

You never said what kind of bike. I do know that there is no easy way to fix your boo boo. Without a doubt the head must come off. A machine shop may have a better way to heat those studs and remove them. I just feel for you, and one of the maby reasons I will never volunteer to work on something that I cannot afford to replace

[Tat2demon]

Its an 82 cb900 but studs are studs.

Yeah this is the last time I work on anyones bike but mine.

[IanDMacDonald]

You're going to have to get a torch on those studs, but I'd be scared tgat you will hurt the surrounding metal.

[Tat2demon]

Im not even opposed to cutting them flush, drilling and tapping. The problem is the extractor that broke off.

[jwhughes3]

Try a diamond dust encrusted tipped drill bit... It should be harder than the extractor but will be slow going. Use cutting oil.


John

[DGXSER]

Option is to pull the head and take it to a machine shop, have them mill it out. They can mill it to the minor thread diameter, then you can retap the threads.

[Tat2demon]

Option is to pull the head and take it to a machine shop, have them mill it out. They can mill it to the minor thread diameter, then you can retap the threads.

Yeah thats my last resort. I really really dont want to pull the engine if I can avoid it.

[Rasputin]

Possibly something like a Dremel bit with the diamond encrusted bit (or most likely multiple bits) will take the hardened steel easy out away. It would be kind of like a dentist on a tooth but could be done in the bike. Then you could try all the heat and other methods again. Failing that I guess it is time to pull the engine.

[tarzan]

You dont need a diamond cutter. You do need a carbide cutter though.the problem is getting it as close to center as possible. a dremel with a carbide burr will work to get a good divot for a spot to drill. the burr can even cut the ez-out.but a carbide drill will work a little better. of course, diamond is an option, just not necessary. I cut quite a few taps, drills, end mills out. just try not to get frustrated and take your time. Also, that ez-out is hard.You may be able to strike it with a punch with a hammer and shatter it. that would help get it out in small pieces. Then drill a small hole all the way through the stud. Then drill the hole a little larger, a drill size or two at a time, so that you drill it out to the minor diameter of the thread. then peel the rest out like a spring.
as for the studs that are sticking out, I would heat the head around the studs and get it nice and warm, the spray kroil or PB Blaster liberally around the studs. That should draw the liduid in and help free up the studs.

[CaptonZap]

Worst case scenario is that you take the head to a machine shop that has electron discharge machining capability, and have them removed. A lot of shops have them for removing broken studs. Whoda thunk?
Here is another trick that might save you some troubles down the road.
Aluminum has a higher rate of expansion than steel, so after you do as Tarzan suggested, spread some oil on the head, and heat it up till the oil starts to smoke. That is about 450 deg. That temperature will not hurt the head.
I put them in an oven for a while, and that gets them hot all the way through. The oil smoke doesn't go over well with SWMBO, but you can pick up an oven from Craig's List and rig some temporary wiring from the breaker box to the back yard. What ever.
While the head is hot, the aluminum has expanded more than the stud, and you stand a better chance of getting it out. Once you get it to start turning, take an eighth of a turn out, and turn it back in with some Kroil. Back it out a quarter of a turn, Kroil application, back in, etc.
If you try to power it out, the corrosion between the steel stud and the aluminum jams up the threads, it just gets tighter, and your stuck. Keep working it, dosing with Kroil as you work. A propane torch played around the stud will keep the head hot. Thick gloves are recommended.
Good luck, CZ

[Tat2demon]

Making a little progress. Using a couple Dremmel diamond bits, Ive been able to chew about half of the extractor out. Its very slow going but it beats the hell out of pulling the motor/head.

[IanDMacDonald]

Man oh man! And I thought bent valves were thebiggest problem I had . . .

[Tat2demon]

Im at about 7 hours total on this one stud so far. 2 of it using the dremel but Im almost there. After that the drilling and tapping will seem like a dream. For an idea on how slow this is, only about half an inch of the extractor was broken off. So about a quarter inch an hour.

I found out this isnt nearly as frustrating after taking a Vicodin for my back and a nice Black Velvet Toasted Carmel/Dr. Pepper. I think its time for a cigar break.