Drilling out JB Weld from exhaust bolt thread?

[metalfab]

I just saw your post, I have done a lot of jobs like this. If it was me I would stop where you are now and get an M42 cobalt drill bit. The M42 bit is tool steel with cobalt in it that makes it harder than heII, and it is coated with titanium nitride. An M42 bit will cut any normal tool steel tap. That said you have to run the M42 bit real slow like 100 RPM's and use oil on it when you are drilling. If you turn it any faster or dont keep it oiled while drilling the tap is hard enough to burn up the M42 bit. The harder the metal you are cutting, the slower you have to rotate your cutting tool.

Odds are there was a flake of the old bolt in the hole, one little piece of steel left off of the original bolt will lock the tap in place where you cant hardly get it out without breaking the tap. It took a lot of force to break the tap, if you could get a good enough grip on it the odds are the tap would just break again. I dont think you can get it to move. Chips could have locked it up too.

If you totally screw it up you can have the hole filled with aluminum and re drill and tap it. If it goes beyond drilling out the tap you should probably just replace the head. Compared to the work you have done replacing the head isn't that bad. Don't use a helicoil use a steel insert that is solid, a helicoil is like a spring. The solid inserts are far superior. Don't break the cobalt bit, it is almost impossible to drill out, only carbide will cut it. Most hardware stores will carry M42 bits.

[hillsy]

How deep is it in the hole now? You might be able to "sacrifice" some drill bits to get it deep enough to tap a Time Sert in there??

Update,

We are 26 hours in and from what I can tell very little has occurred reaction wise to the tap. Just heated up a fresh batch and flushed the hole a couple times. Going to let it go for another 24 hours and I'm the meantime I'm making some calls to machinists to see how much to zap this sucker out!

Well much like in roulette as is with this motorcycle. When the going gets worse double down. I'm hoping some of you will enjoy this. It's been a pain. So I've tried angling a flex funnel and using epoxy to seal it. That ended up leaking. So I decided to remove the engine. A lot easier than expected which tells me it's going to be a pain getting it back in. I built up a reservoir with latex acrylic caulk. It's chooching right now. Will check tomorrow and replace fresh alum solution.

[img]https://i.imgur.com/feUmUdF.jpg[/img]

here is the engine on its back, with the remaining tap in the hole


Here is the caulk damn I made with the solution in the hole.
[img]https://i.imgur.com/bWAjoke.jpg[/img]

[Gorminrider]

..feeling your pain.. I am scared to death of these stoopid suzuki bolts. and want the alum thing to work for when I b*gger one of mine.... Sealing the alum/water conveyance in such an awkward spot is definitely the tricky-bit...

[chuck hahn]

Few of them on Ebay now. I would make a parts wanted section add first. The forum guys will not try and sell you a head with an issue..broke off studs, scarred cam journals etc etc.

Hey I'll take your two cents! I really want to minimize the down time involved in getting this going. What's a fair price for a head?

[chuck hahn]

By the time you take it to a machine shop...pay them..and the down time involved youll be ahead of the game to just get another head and swap it in. Just my 2 cents worth anyway.

Taking this forum thread deeper than the one I tried to tap! Appreciate everyone's input. So I've made a strong super saturated solution of hot water and alum. I tried to epoxy a flex funnel around the hole. It's leaking. I'm going to let it rest and seal it up tomorrow morning then see what happens over the next 24 hours. In the meantime if anyone has a spare head for a 1980 gs850 let me know. If it's cheaper than taking it to a unexpecting machinist then that's the route I'll go! I'm grinning inside despite my furrowed brow because I know I'm being challenged and I'm going to finally get this right.

[AMK]

You must have hit the bottom of the hole with the tap. I admire your persistence.
These cases command thought and patience.
The advice for a different head is good. You'll inevitably p**s off the machinist because he could have
had a berry job at first but all of his options are gone now, except for EDM.
You need to offset the price for another head with EDM now.
Although a machinist with your persistence can probably do it.

[chuck hahn]

Im with JT. Scrap that head and find a replacement.

[JTGS850GL]

If the alum doesn't work then you might want to just consider picking up a replacement head off eBay or one of the members here. Might end up being faster and cheaper in the end. I have an 850 1982 head and matching valve cover somewhere at the house.

Alright update time!
Received my Walton tap extractor. Got it all setup, looks like a nice bit of tool, and unfortunately didn't work for me. End up breaking two of the fingers. Followed the directions but this tap is in there tight and deep. I've tried chiseling it out with a center punch, heating and cooling it, and now tried extracting it. All to no avail. I'm going to try the alum trick, I've seen it on YouTube before. Going to take good pictures of the attempt. Hope to come back with good news. Otherwise I'm not sure what to do next. Call a machine shop for EDM I suppose. Have around one month to get this all done. Haha man this will be a hoot if it all comes together.

[AMK]

I want somebody to try the alum trick suggested elsewhere on GSR... Granted, building a waterproof "dam" there is going to be tricky- a plastic straw or vinyl tubing might do it with silicone... Even if it only dissolves the thinnest ends of the tap threads , it is going to help. Maybe a paste of alum and water packed in .....

http://forums.sohc4.net/index.php?topic=73735.0

https://www.youtube.com/watch?v=fqZYgReuywM

That's interesting. I saw that post but just blew it off.
I wonder if it would just take longer on a hardened tap. His condition would be perfect to try that and let us all see if it worked.

+1 on this idea.

[Gorminrider]

I want somebody to try the alum trick suggested elsewhere on GSR... Granted, building a waterproof "dam" there is going to be tricky- a plastic straw or vinyl tubing might do it with silicone... Even if it only dissolves the thinnest ends of the tap threads , it is going to help. Maybe a paste of alum and water packed in .....

http://forums.sohc4.net/index.php?topic=73735.0

https://www.youtube.com/watch?v=fqZYgReuywM