In a bit of a pickle with some sheared bolts

I have one exhaust header that now has two sheared bolts. It looks like one was probably missing the whole time I've owned the bike and the other snapped while I was riding the other night.

To make matters worse, these are on cylinder #2 and the outside bolt lines up pretty closely with the frame tube so I cant really get at it with a regular drill bit or extractor. For this one I've ordered some 6" cobalt bits and I think I can make due.

The other bolt is the real problem because I snapped a drill bit off into it and in the process of trying to twist the broken piece of bit out it broke again flush with the bolt. So there's no way to grab it. I started drilling a second hole underneath the snapped bit in the hope that I can get it to loosen up and get it out of there but I'm seriously worried that I'm going to mess this up!

Any ideas out there about how to deal with all of this? As a backup plan, if I can't get the old bolts out do you think it would work to just weld some studs in place?

 

For steel studs in aluminum, welding a nut works best in my opinion. Lots of youtube videos on that if it doesn't make sense. One of those is broken off a little deeper and wont be super easy. I can't tell if the photo is before or after snapping the drill bit off.

The heat from welding helps loosen them up. I really despise any form of easy-out and find they have a low success rate if the original stud is seized enough to snap. But you'll have the same space constraint issues with welding as drilling. Even if continuing with the drilling method, I would heat that stud to red a few times. Heat that drill bit remnant to soften it.

Maybe load the bike up, take it to a machine shop for their opinion. You might be weighing their labor against replacing the head. Good luck!

 

Had a similar issue with the 650 I used to have. Multiple studs were snapped off, a couple were missing.

A friend with good intentions tried an ez out against my recommendation, and snapped it off.

Great. Now I not only had several studs snapped off, but now I had an ex out remnant I had to find a way to get out.

I ended up using a carbide cutting tool on my dremel to carve out the snapped ez out.

I then drilled and re-tapped all the stud holes to accomodate studs a bit larger than stock. And brass nuts and washers to prevent hardware seizing due to heat and corrosion. Not sure how oversize would work with stock exhaust ring nuts, but it worked for the 4-1 system that was on my 650.

 

Thanks for the feedback guys. Really appreciate it!

I called a couple of shops today hoping I could just cart the bike to a machine shop and get it over with. One guy who specializes in old bikes around here told me that they would NEVER get the studs out using the welding technique and that I would have to pull the head and send it to a shop with an EDM machine...
So I think that's going to wind up being hundreds and hundreds of dollars (not to mention the myriad issues that will probably be created from removing the head on a perfectly running engine).
I'm going to get a few more opinions about the welding technique. Has anyone ever actually done this successfully on this bike?

Sounds like quite the journey @short_circutz I'm not sure if oversized studs will work with those rings either... Doesn't seem to be any wiggle room there.

Looking for some good news,
E

 

Conventional EDM sounds expensive, mounting and lining up the stud holes, making the correct size electrode, the slow process of removing the stud. I don't see the downside of centering up a nut over the stud hole and filling it from the stud to the top of the nut with a mig. The recessed stud may cause a bit of thread buggering that would need to be chased with a tap if the stud didn't clean them out upon removal. probably would be a good idea to pack the threads right down to the stud to prevent the weld spreading out into the thread area at the stud.

 

I've removed quite a few studs and snapped bolts by welding a nut. No, not exhaust stud on a 650, but intake studs on a 750. And other places in both aluminum and cast that don't say Yamaha on them. Aluminum is actually easier and less apt to melt out the head. Point being, it can be done and its fairly standard practice and I will always attempt it before trying to drill. Don't want to disparage the shop you've consulted, but there is definitely options other than EDM. Might need to consult a farmer rather than a machinist.

 

And there's also a chemical technique. I've never attempted it, but a way to dissolve the steel and not affect the aluminum. Nitric acid??

 

Haha! To be honest, I was kind-of HOPING someone would disparage the shop I talked to because it seemed excessive and I was beginning to feel really discouraged about it.
Thanks for re-instilling a bit of hope in this dire situation I'm going to reach out to some competent welder types and see if we can make something happen.

 

Good advice! I actually watched a tutorial where they talked about a particular welding rod called X-Tractalloy™ that has additional/special flux on it to prevent the weld from encroaching into the threads. Sounds like I may need some of that.