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Discussion Starter · #1 ·
Here's the latest foulup working on my '07 Ninja 650R. I brain cramped and snapped off a bolt securing the head to the lower half. This bolt is one of two located next to the camchain but on the outside of the head. The book calls for 12nm torque and the bolt snapped somewhere around 20 - 22nm. The remains of the bolt are securing head to block. In other words, if the broken bolt were properly torqued I wouldn't need or want to do anything. I'm willing to entertain crazy thoughts and ideas on this one. As I see it my options are:

1. With difficulty, drill out the broken bolt. That may not even be possible because of the location, needing an extender, not being able to use an EZ out, etc. The operation would probably chew up the threads so I'd need to rig a nut and bolt replacement.

2. Leave the bolt in and don't worry about it as opposed to worrying the overtorqued area will warp the head.

3. Use the thinnest cutting tool available to go in sideways and cut the bolt. That will chew up part of the aluminum on the outside but would allow me to pull the head and drill out the remnants.


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My condolences.
Now that the head is off the bolt there’s no tension on the threads so it won’t require much force to remove it. It’s in there loose. Drip some penetrating oil on it. The problem is turning the stud.

A small ez-out will work here.
You will have to fabricate a bushing that will center a center punch and drill bit so that you get the exact center. Maybe use a small nut.

You can buy a small reverse drill bit that you drill in with the drill in reverse. I believe I’ve seen them at Home Depot. According to what I’ve seen on YouTube, sometimes the drilling action alone will back out the stud. If needed the ez-out comes next.

Whatever happens, you’re already at the "as good as it’s going to get" point. A half hearted attempt with improper tools and things get way worse.

The one thing you can try is if you have a really hard pointy implement such as an ice pick, if you can punch it on the outside edge at an angle which might start the stud to unscrew. I use that method to take out those tamper proof screws under the ignition. Just try not to bugger up the top of the stud in case you have to drill it.

Also, they make six inch 1/4 inch hex extensions like you see on the end of a screw gun. I have one. And they make drill bits with one end being a hex that will fit the extension. AFAIK, the ez-out are all square drives but I know there’s hex-square drive adapters.
 

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I agree with Zed7. If there is a tiny burr on the broken part of the bolt then using a small fine bladed screwdriver and tap hammer you can sometimes tap the bolt around enough to raise it a few threads and then use needle-nosed pliers to unscrew it. I've done that a few times.
 

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Discussion Starter · #4 ·
I thank you all for the replies and ideas. I spoke with a friend and engineer today and feel much better. Here's my takeaway from that converstation:

1. The purpose of torqueing the bolt is to prevent it from coming loose.
2. The bolt's purpose is to keep the head/block gap constant.
3. Extra torque pressure does not close the head/block gap but is absorbed by the bolt.
4. When the bolt head snaps off pressure is relieved and theoretically the bolt is free spinning.
5. As long as the bolt is threaded to block and head, proper gap is maintained.
6. The engineer's thinking crystallized when I told him this bolt is tightened last in the sequence and after all the bolts located under the valve cover. It's a "feel good" bolt and essentially not necessary.
7. The bottom line is that nothing need be done other than maybe silicone the bolt to keep it from moving.
 

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Discussion Starter · #5 ·
My condolences.
Now that the head is off the bolt there’s no tension on the threads so it won’t require much force to remove it. It’s in there loose. Drip some penetrating oil on it. The problem is turning the stud.

A small ez-out will work here.
You will have to fabricate a bushing that will center a center punch and drill bit so that you get the exact center. Maybe use a small nut.

You can buy a small reverse drill bit that you drill in with the drill in reverse. I believe I’ve seen them at Home Depot. According to what I’ve seen on YouTube, sometimes the drilling action alone will back out the stud. If needed the ez-out comes next.

Whatever happens, you’re already at the "as good as it’s going to get" point. A half hearted attempt with improper tools and things get way worse.

The one thing you can try is if you have a really hard pointy implement such as an ice pick, if you can punch it on the outside edge at an angle which might start the stud to unscrew. I use that method to take out those tamper proof screws under the ignition. Just try not to bugger up the top of the stud in case you have to drill it.

Also, they make six inch 1/4 inch hex extensions like you see on the end of a screw gun. I have one. And they make drill bits with one end being a hex that will fit the extension. AFAIK, the ez-out are all square drives but I know there’s hex-square drive adapters.
You are either very knowledgeable or intuitive about the pressure being released when the bolt head was broken off. My engineer friend came to the same conclusion. No worries about the head warping now. I'm inclined to keep the bolt in place to stabilize the head to block gap and put some silicone in there to keep the remaining part of the bolt from moving.
 

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You are either very knowledgeable or intuitive about the pressure being released when the bolt head was broken off. My engineer friend came to the same conclusion. No worries about the head warping now. I'm inclined to keep the bolt in place to stabilize the head to block gap and put some silicone in there to keep the remaining part of the bolt from moving.
Put it this way, I’ve removed a few broken bolts in my day, no college degree needed. If rust or corrosion is not a factor, the remaining stud is only in there finger tight.
I wouldn’t call that a "feel good" bolt. Kawasaki wouldn’t have gone through the expense of putting it there for nothing. Plus they ruin the clean lines of the head.
With the head of the bolt gone, it’s no longer doing its job. There’s a clearance hole in the head section and a threaded portion in the cylinder portion. Zero clamping force.
There’s now unequal pressure on the head gasket. If Kawasaki over engineered the engine then maybe you don’t need that bolt after all. But if they engineered it just right… you should replace it.
 

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Discussion Starter · #7 ·
Put it this way, I’ve removed a few broken bolts in my day, no college degree needed. If rust or corrosion is not a factor, the remaining stud is only in there finger tight.
I wouldn’t call that a "feel good" bolt. Kawasaki wouldn’t have gone through the expense of putting it there for nothing. Plus they ruin the clean lines of the head.
With the head of the bolt gone, it’s no longer doing its job. There’s a clearance hole in the head section and a threaded portion in the cylinder portion. Zero clamping force.
There’s now unequal pressure on the head gasket. If Kawasaki over engineered the engine then maybe you don’t need that bolt after all. But if they engineered it just right… you should replace it.
Problem is the location directly next to the head and needing a drillbit extender to get there. It's possible the bolt will come out with extender arriving today. That failing, and if and when it has to come out, I'll hacksaw sideway and cut the bolt in two, remove the head and easily remove the now separate sections from the head and block.
 

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Discussion Starter · #9 ·
If you remove the head you’ll wind up with that stud sticking up a half inch. But I think the stud should come out easily where it is.
Good luck.
It's tough to convey all the particulars. The broken bolt is fully threaded. That engine head doesn't come off unless the bolt is either cut in half or removed. The bolt's purpose is to stabilize the distance between the head and block and it can do that without it's head. It's staying in unless removal is possible without damaging the threads. I'll make an attempt.
 

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It's tough to convey all the particulars. The broken bolt is fully threaded. That engine head doesn't come off unless the bolt is either cut in half or removed. The bolt's purpose is to stabilize the distance between the head and block and it can do that without it's head. It's staying in unless removal is possible without damaging the threads. I'll make an attempt.
So both pieces are threaded? I get it. If that’s the case then leaving it in wouldn’t be the worst thing but I still believe it will come out easy enough.
I doubt the tapping method with an awl would work in that case. You’d need to drill with ez-out.

Me, I’d take it out because it would bug the crap out of me.
 
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