TOPIC:

A nut could have been easily welded to the broken nub. The heat from welding will help loosen the galvanic corrosion locking the bolt to the head as well. Too late now though (I think.)

Option 2: LH drill bits to drill out the old bolt. Grind the nub flat, center punch, then progressively increase the drill bit size, always staying centered, until the old bolt is just a shell. 90% of the time the old bolt will spin out on it's own when the diameter of the hole approaches the thread size. I've used this menthod many times and it's yet to fail. You just need to be careful to not drill crooked or off center of the old screw.

Hey all, here is an after picture from the failed operation. Not the small crack in the casing near the top. From what I have read thus far, I think that soaking it in a strong penetrating oil and drilling the bolt out will be the best option and then re-tapping the threads if necessary. My biggest concern after that, is the small crack near the top of the holder...

If I had the ability to remove the engine then that could be an option. But currently I it will need to stay in the bike unless I come across better financial means.

I am sure others will chime in with other suggestions but you are in some trouble because the hole you drilled is off center by quite a bit. The first idea that pops into my head is to take a Dremel or better yet Foredom type tool and with a very small carbide bit work the remainder of the broken on a slight angle thru the "meat" or thickest part of the broken bolt. If you can split the remainder it will literally fall in on itself and you can pick it out. Don't try to remove all of the broken bolt, all you need to do is make one straight cut thru it. You can buy small very small carbide bits for this job, but keep the bit straight in the hole not at an angle. You want to avoid any further damage to the hole itself. Regarding the small crack, I wouldn't worry too much about it right now. If you remove the broken bolt you should be able to get a new one in that goes beyond the crack and into good material but watch how tight you assemble it. And if you are successful in getting the broken piece out most certainly run a tap in that hole to clean the threads up as best you can.
Rick H.

I think you should still pull the head off to work on the broken bolt. Working on it while the engine is in the frame is not conducive to success.

...hence why we could not drill a perfectly straight hole.

I will have to think about that one because I do not have the ability to lift this massive thing from the frame and is a bit outside of what I feel comfortable doing. With that said, whatever next steps I take will dictate heavily whether or not I can ride this thing again with ease.

I bet I will need a mechanic to remove this engine or at least some machinery.

Thank you for your recommendation. The carbide bits are a fine idea. I may have to wait some time to acquire the tool but overall it seems like my options are dwindling. I would prefer to ride this bike again as it is my first motorcycle and am enjoying the challenges that buying a 1980 motorcycle entails.

I am going to spend some time away from this project as I need to collect and weigh the risks and whatnot.

There seems to be several ways to get the engine out without too much effort, one of them involves laying the whole machine on its side and sort of tipping it out and sort of reverse the actions to get it back in. There are a few threads around here that tell you how. It should come out to enable you to get the right angles on the drill.

If you make yourself a steel template that will bolt into the good hole and the other hole is much smaller, you may be able to progressively drill out carefully stepping up a little each time until you get to just below tread size and you may be able to work out what is left. It sounds like the aluminium has corroded around the thread and it won't be easy.

Don't be too concerned if you damage the thread a little bit, because you can open up the hole a little more and insert a helicoil or thread repair insert, usually made os stainless steel. This should reduce the incidence of corrosion re occurring again.

As the guys here have said, the best bet is a machine shop, but with a little care you should be able to do it. Have done it myself many times.

Can't the head be removed with the engine in place?

A dremel tool with a small diameter bit could be used to grind out what's left of the bolt. It will be tedious work but doable. Harbor Freight sells cheap disposable bits that may be useful. A tap then can be used to rethread the hole or better yet, get a threaded insert in there because the hole looks like it's going to be oversized.

You might want to buy some welding flux-cored rods and do the repairs. You can watch this video,

The trick to welding with these rods a) surface must be cleaned with wire brush in order to remove oxidation
b) do not apply heat to rod, rather apply heat to the surface you are repairing and let the rod touch the hot surface and melt.

650ed wrote: Just saying.........

That's the first we've seen of the updated formula using PSF. We've used the ATF/acetone 1/2 & 1/2 mix for years, based on the original article. We call it MMF, for Magical Mystery Fluid. We'll stir up an ounce of the PSF/acetone next time we need some.

Common WD40 is not a lubricant. They do, however, make a penetrating lube.

Too late for this head but, there's a few tricks that work for us when confronted with broken bolts.

First is not to break it. Well..., duh! If we even slightly suspect a fastener is seized, we'll apply MMF repeatedly for days or weeks prior to attempting removal. Strike the fastener using a hammer & punch often. Not hard, just enough to break the hold of corrosion. Use copious amounts of heat from a heat gun, propane torch or whatever is appropriate during the MMF soak/strike phase to heat-cycle the fastener in it's bore. Attempt removal when very hot after a period of days or weeks using an impact driver or wrench set to lowest torque.

If broken above the surface, weld a nut to the protruding end. The heat shock will often loosen the remains. If that's not doable, grind a minimum amount off the end to be square with the axis of the fastener. Press a short piece of aquarium tubing over the broken end to center the punch, and use a very small centering punch pushed into the tubing for a precisely-centered punch mark. This is much more accurate than eyeballing. Proceed to drill slowly using a high quality, cobalt reverse-twist drill bit. No HF crap. Another pair of eyes helps keep the drill on-axis. If possible, drill all the way through to the other end of the fastener and use a syringe or spray can straw to get MMF to the bottom of the hole to soak it from both ends. More days of soak/strike/heat-cycle. Attempt removal when very hot after a period of days or weeks using an impact driver or wrench set to lowest torque.

If the fastener is broken below the surface, same as above, but push the aquarium tubing into the hole to center the punch and/or drill bit.

An easy-out in a relatively thin bore such as this head can split the seized fastener, which will then split the surrounding aluminum. We've had to take a head to a machine shop after that happened to have fresh aluminum built up by welding onto the remains & drilled/threaded again to accept the mounting screw.

Good Ridin'
slmjim & Z1BEBE