1984 GPZ550 - Exhaust Stud Broke off in Head

And by broke off, I mean it's deep within. I just acquired this bike as a failed project from a friend and am resurrecting it. I know I have 2 options...

1. Find some way to extract the bolt, drill it out, tap, use an insert, something like that? Pointers?
2. Buy a replacement head off EBay - or another online retailer - suggestions on someone reputable?

Also, it needs other parts like chain, sprockets, brake discs/pads, head stock bearings, so pointers on a great retailer to get those parts would be much appreciated.

The PO chopped off the tail so it's going to be some sort of Cafe/bobber/something build, it was free so I'm going to have fun with it. Other than the exhaust stud problem, it runs fantastic and has a 4-1 header, gotta look up the brand. I just picked this up yesterday so I've got some research to do.

All help is appreciated and I'm super stoked to be back in the motorcycle game again. Thanks!!!

I would try to repair it first.

I had a really bad one that the previous owner had 'repaired'. Ended up having the whole area aluminium welded to build it back up again to be re-tapped. So anything is possible.

Its a real common problem, so there are loads of how to videos on you tube. Check out a few first and note some of the techniques.

Most involve centre punching the broken stud and using a screw extractor or lefty drill bit, then helicoiling or using an insert if the thread is trashed.

As to parts, there are loads of great retailers out there - depends on where you're located and how long you want to wait for delivery. Partzilla (US), CSMNL (Holland) for oem parts. Z1 enterprises (US), Z-Power (UK), Brakecrafters (US) for aftermarket. I'm in australia and buy parts from all over the globe.

Good luck

Google "EDM" bolt removal in your part of the world. This is a process of spark eroding the broken stud. 

Thanks for the info, it's very helpful. I'm an experienced fabricator and welder so I shouldn't have too many issues. I'll tear into the bike this weekend and start the repairs.

I'm based out of Portland, OR.

Should be fine with good drill bits (exhaust studs tend to be very hard due to the heat cycling) If it all goes horribly wrong there is always these to get you out of trouble 
 

wrote:

Google "EDM" bolt removal in your part of the world. This is a process of spark eroding the broken stud. 

What Wookie said.  I went down a rabbit hole earlier this year on a fork axle clamp broken stud.  I contacted a local disintegrating service(thanks again Wookie!).  Had that back in a few days and went on about my business.  

Drilling out broken bolts is not difficult.  It just takes some care.  If you are hamfisted, don't even attempt it.  Find someone to do the work for you.

First thing, buy some LH drill bits.  Harbor Freight or Amazon sell sets for cheap.

Starting with a small bit, like 1/8", drill into the center of the broken screw.  It's absolutely critical that you hit the center.  If the hole starts off center, you will have to work the bit sideways until you get a hole dead in the center of the broken screw.  Use some PB Blaster or similar for lubrication.  Once you do that, move the next larger bit and drill into the first hole.  Slowly step up in size, bit by bit, using lots of lubrication, making sure you are staying centered in the old screw.  As you get up into the larger bits, the screw will be just a shell of its former self, and typically, it will just spin out on its own as the shell gets thin.  Worst case, you will have to get a tap to clean the shards of old threads.  That's a rare case though.

A bore guide is nessesary to hold the right angle and the center during drill process!

I drilled out a lot of broken fasteners working on the end of the assembly line for 30+ years. New folks on the line from time to time and figuring out how to use air tools (some for the first time) meant I got plenty of practice!  As has already been mentioned,  the most critical part of the process is center punching the broken piece dead center and drilling the pilot hole straight. If there was a threaded hole in the piece I was working on that ran parallel to the broken fastener I would use a bolt or screw as a guide to stay straight.(in this case the neighboring exhaust stud) I also had the advantage of using a small air drill and a new bit for each attempt. You do not want to break off a drill bit,  that's when the project turns to Poo! Drilling a broken exhaust stud out while the cylinder head is on the bike will be challenging! Those repair studs are cool Wookie!

Good Luck,  Mike 

Here's a pic of the damage...

I've removed and drilled out plenty of studs but this one... this one's a doozy, see attached pic.

Here's a pic of the bike, it needs some work but it has potential. Lots of fixing poorly executed modifications. Good thing I can weld...

Also, I'm having trouble finding clear answers for this. What are the threads on the exhaust studs? With the location of this broken one I can easily access it while the head is still on the block. I'm thinking about threaded inserts from mcmaster...