That's a great idea Digger.  I never would have thought of that.

Think again about Verslagen's  thread forming up that thread, rolling up the material from the larger diameter wall into a form fitting rolled up thread that exactly matches the bolt root diameter.  

With zero clearance to the round bolt form that rolls it up no less.

Me, I say tap it and make your tapping cuts as long as the part you intend to thread to allow free collection/passage of swarf and oil.

(can't forget about the swarf if you are thread cutting, now can you -- gotta make some clearance in them cuts to hold all them minichips, no?)

Ive seen threads pull out like that. I dont see the part there having the corner on the back side/outside of the thread section that would lock it into the tapped out hole, BUT, If that Is a thread repair kit & it Has pulled out,, thats a problem I wouldnt want..


In fact, he has a problem I wouldnt want already.


Beauty supply stores have cuticle sticks, reasonably strong, a cottonball can be used to load it, start a few strands around & around, then go to the tip, keep them tight, build up a Q tip lookin affair.
Or, cut strips of T shirt & use the sticks to poke them down, leaving an end out for retrieval, pipe cleaners work for some jobs,
Like I said, find out the depth of the hole, compare to the bolt. If its 1/2" deeper than the bolt is long, youre not screwed.

It MIGHT even be threaded down there.

I dont like the file for cutting bolts into taps, I like cut off wheels & I aim the slot so as to pass between the edge Im starting the cut in & the center of the bolt, so the slot is scraping the edge of the hole. That means a turn of the bolt & pull it & THAT means being absolutely certain
you find the start thread & dont start a new cut or youll wind up in worse shape than youre in now.DRop it in, turn it backwards till it drops, then finger tighten back in & start the cut. Buying a proper tap may be a good plan here, but, youll may need to find someone to braze an extension on, taps that long are hard to find & expensive.

Now, If you were to discover that there is a small car out there with head bolts that size you could get a couple & use 1 to make your tap.

Or, stop by your local Nut & Bolt supplier, not Lowes, but a place that sells nothing but threaded fasteners, they mite be able to help you. Once you know the depth of the hole, youll know what your options are,

Dang MIke,, I pretty much already covered that, only I didnt use a baseball bat,

I had that happen long time ago with the other bolt in front of that one. IIRC, the rear bolt was a L130 and the front one is a L125. So I ordered another two L130 bolts and did what Oldfeller did. Turning one bolt into a tap with a file, but also filed a little clearance behind the cutting edge. So i went to cut about a 1/4 turn at a time and removed the bolt and blew out the shavings. That part is very important as the shavings tend to ruin everything when binding in the whole and bunching up. Eventually I had the bolt all the way in and then used the other new bolt and tightened everything down. Works like new since a couple of years now.