I’d be really hesitant to drill on that bolt. I’d exhaust every other measure first. Drilling on that could damage what’s behind it if you drill just a little too far and you no doubt will end up with some metal shards inside that cover. I would try a hex bit or torx bit that is a little larger than what’s there now and carefully hammer it in to place.
I was going to suggest you do a few things that might work, but when you said a screwdriver was a 4 hour drive away, I changed my mind. What you need is to find someone near you who is a biker and has tools and knows how to use them. Look around for where you see bikes parked and start asking questions. It doesn’t matter if they are Harleys or Hondas, this is not a special Honda issue.
If that fails take it to the oldest mechanic you know, older is better because after 30 or 40 years of this stuff you learn ways to get problems solved. Again, it’s not a motorcycle problem. Maybe a good machine shop could help, or a place where they work on construction or farm machinery.
Looks like a plug with an o-ring seal. Blaster won’t get past the o-ring so forget about that. I wouldn’t pound on it the part its screwed into is cast or pot aluminum and you could crack it. Allen wrenches come in both metric and SAE sizes the common ones in a collection like a swiss army knife. If you don’t have both,get them and try the closest one to the egged out hole. If that ddoesn’t work slot it with a dremel and use a slotted screw driver with flats on the stem. Put a crescent on the flats. Press with your palm and all your weight into the screw driver as you turn the crescent for leverage. Match the slot to your driver blade width as close as possible and it’ll come out. Heat to loosen the O-ring would be next. I’d never try using an extractor on this type of plug. Once you get it out or see the new one you’ll know why.
I agree. You’ve got a $6 Chinese made EZ out and a drill bit thats just asking to create more of a problem. Wait till you get the new one. Even if it isn’t a torx bolt, remember there are SAE and metric allen wrenches that will just be off enough to strip the hole some. Might still be able to get a bite with the proper size wrench.
On a positive note, the plug is probably made of aluminum so it should be easy to hack around on.
Maybe slightly drilling into one side of the plug (short of the threads) and then trying to tap it loose with a pin punch would rotate it out.
I could be dead wrong but my gut feeling is that the plug may not really be that tight and that someone just wallowed the hole out with an undersized Torx driver rather than gutting it by overtightening.
Always something… 
OK got me thinking and looking at that again, I think a reasonably easy way would be to drill a couple holes just outside the socket, opposite each other, and tap in a couple roll pins in it. Then you can take any kind of pry bar between the two pins to unscrew the cap. If you have enough to drill in maybe a quarter inch for the roll pins, that should be enough. They’re only about 50 cents and one should have a supply of them anyway. I’d still wait for the new part first to make sure there’s enough metal to drill into.
I’m 99% sure it’s a 10 mm Allen fitting because of the way it fits. I’ll confirm that when the new plug arrives. At the hardware store I didn’t see any larger Allen wrenches or comparable hex wrenches or sockets.
I’ve decided to take the night off and not work on the bike again until the part arrives.
I’ve also decided to see if a friend of mine has a Dremel tool and a large screwdriver. I’ll hold on to the spiral extractor/drill bit set in case the first method doesn’t work, but if it works, I’ll return the kit to the store unopened.
The only thing I’ll say in defense of the ham-handed prior mechanic - that cover was designed to fail, made out of aluminum, small size allen fitting compared to the large O-ring that can bind it up pretty well. Would have been much better to cast a large hex boss on it.
Add to that the fact that Honda recommends checking the valves every 8,000 miles, and you’re right. That part should have been designed better. If I was running a service department, we’d have a box of these plugs on hand.
It’s possible Honda realized they made this mistake. I wouldn’t be surprised if the replacement OEM part is made of a harder material.
A good illustration of what happens when an impact wrench becomes the universal tool.
Still think drilling a couple 1/8" holes and tapping in a couple roll pins would be easier than a dremel. Plus you could get a lot more torque on the roll pins than a scewdriver in slot. Once it turns a little it should screw out very easily.
@ Whitey,
I’ve worked on more than my fair share of Honda 52 degree V-Twins over the years.
That cap is made of plastic, so please don’t try to apply any heat to it at all, otherwise you will end up with a big mess.
That cap is supposed to fit an Allen Socket, usually either 8 or 10 mm, but it looks like one of the previous numb-nuts who worked on your bike used a standard size allen wrench.
If you have a good variety of allen sockets and torx socket at your disposal, play around until you find one that can get it off. Notice that I say to use sockets, and not the little angle key things. If you have to, dremel the angle off of a key, and put it into that size socket in order to make one.
As for the timing, all you really need is to pop off the smaller plug, as that one shows you the timing marks. If you put the transmission into top gear, and pull out 1 plug on both cylinders (it’s a 2 plug per cylinder setup, correct?), you can rotate the engine with the rear wheel until the timing marks line up perfectly. That will allow you to check and adjust the valve clearances without needing to get off the larger plug.
Good luck!
BC.
I will stand corrected seeing as you apparently know the bikes better than I do.
Just some food for thought seeing as how this is plastic what about the idea of heating up a piece of 3/8 square stock of some sort or a large common screwdriver tip, allowing it to burn its way in a bit, and then quickly douse it with cold water?
That might get enough grip to allow removal of the plug which is going to be junk anyway.
Actually, the 10mm allen socket isn’t that expensive. I could pick one up at Lowe’s (they sell them individually), squirt some Loctite waterproof adhesive (or an expoxy resin) in the center of the plug, stick the allen socket in there, let it harden, and remove it with a ratchet. I think I might give that a try when the part arrives. If it’s not here by Thursday, I’ll try to adjust the valves without removing the plug. I have school tomorrow night.
I think you’ve got it. Body putty, epoxy, or whatever and you should be in business.
I would vote for the screw driver method.
Anxiously waiting for results.
Me too. I’m going through motorcycle withdraw as I’m too busy to finish the job I started. I wish I had found this problem before I removed the valve covers. They were a pain to get off, so I can’t just put them back on and do the job later. I’d like to work on it after work today, but it’s getting dark pretty early and the new part hasn’t arrived yet. I’ll probably finish the job sometime this weekend.
Thank you, guys. You’re the best!
If you are really thankful, include a pic of the bike when you are done. I’ve done carbs and valve adjustments on my Vstar 650 last year and really appreciate the effort you are putting into this.
Labor of love that not everyone understands. Especially if you are like me…learning as you go. Good luck.