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I had to fix mine, so I thought I would try to do a step by step with pics. Hopefully this helps someone.
1. Find your proper size kit. Mine was a for a 1990 750 which uses a NGK JR8C or JR9C. I think the bolt size was a M12 x 1.25. The tools are (from left to right) Reamer/Tap, thread insert, thread insert tool.
Here is stripped plug cavity.
2.Insert reamer/tap into spark plug cavity. Make sure it seats square. Begin to turn by hand. When you feel the reamer/tap start to securely cut the thread, you can begin to turn the tap with a socket, mine required the use of a 12mm socket. Turn slowly and avoid any sideward force.I already had my cam cover removed, but I think you can do it with the cover still on.
3. As the reamer/tap cuts to make the thread, the metal that is being cut falls into the cylinder. Now its time to take out all of the metal shavings you just dropped into your combustion chamber. I used a magnet. BE VERY VERY THOROUGH. It can take up to an hour or more to get all of the shavings out. (Technically, you won't get ALL of the shavings out) Take your time and do it right. You can use compressed air to help, but I didn't, seeing as my cover was off, and the shavings would have gone all over my cams,valve stems, etc..
Its blurry and you can't see it all, but there is alot of metal on here.
4. Now its time to insert the thread.
Its VERY important not to remove the tang (center metal piece) from the insert until AFTER the insert has been installed. That is how the insert tool threads the insert down into you newly tapped threads.
5. Seat the insert on the insert tool.
6. Seat the insert tool and body over the cavity, and begin to turn the insert tool clockwise to install the thread insert.
My pics don't show, but the insert tool is a 3 piece unit. It has the threaded tool (the piece with the T handle). The stopper. (the round piece right under the T handle) And the tool body. (The piece that you see here, with the Helicoil sticker). Each piece has a specific function and your kit should come with basic instructions, but if you have problems, just PM me and I'll explain it fully.
7. Set the stopper the approximate length of the spark plug thread depth, so you don't insert the thread to far down the bore. Turn the T handle slowly and carefully and stop when the stopper comes in contact with the insert tool body.
8. Once you have installed the thread, turn the handle counterclockwise and remove the insert tool.
9. Now you will need to break of the tang from the insert. To do this a LONG set of needle nose pliers will be needed.
10. Make sure and give it another once over with the magnet, especially since the tang will most likely have fallen in the cylinder. Check to see if the insert is about 1mm or 2 down from the top of the cavity. If so, insert spark plug and tighten down. If it's good, your all done. Reassemble and run.
This is my first how to. I hope that I was thorough and specific enough. If I left anything out, feel free to say. I welcome constructive criticism.
1. Find your proper size kit. Mine was a for a 1990 750 which uses a NGK JR8C or JR9C. I think the bolt size was a M12 x 1.25. The tools are (from left to right) Reamer/Tap, thread insert, thread insert tool.
Here is stripped plug cavity.
2.Insert reamer/tap into spark plug cavity. Make sure it seats square. Begin to turn by hand. When you feel the reamer/tap start to securely cut the thread, you can begin to turn the tap with a socket, mine required the use of a 12mm socket. Turn slowly and avoid any sideward force.I already had my cam cover removed, but I think you can do it with the cover still on.
3. As the reamer/tap cuts to make the thread, the metal that is being cut falls into the cylinder. Now its time to take out all of the metal shavings you just dropped into your combustion chamber. I used a magnet. BE VERY VERY THOROUGH. It can take up to an hour or more to get all of the shavings out. (Technically, you won't get ALL of the shavings out) Take your time and do it right. You can use compressed air to help, but I didn't, seeing as my cover was off, and the shavings would have gone all over my cams,valve stems, etc..
Its blurry and you can't see it all, but there is alot of metal on here.
4. Now its time to insert the thread.
Its VERY important not to remove the tang (center metal piece) from the insert until AFTER the insert has been installed. That is how the insert tool threads the insert down into you newly tapped threads.
5. Seat the insert on the insert tool.
6. Seat the insert tool and body over the cavity, and begin to turn the insert tool clockwise to install the thread insert.
My pics don't show, but the insert tool is a 3 piece unit. It has the threaded tool (the piece with the T handle). The stopper. (the round piece right under the T handle) And the tool body. (The piece that you see here, with the Helicoil sticker). Each piece has a specific function and your kit should come with basic instructions, but if you have problems, just PM me and I'll explain it fully.
7. Set the stopper the approximate length of the spark plug thread depth, so you don't insert the thread to far down the bore. Turn the T handle slowly and carefully and stop when the stopper comes in contact with the insert tool body.
8. Once you have installed the thread, turn the handle counterclockwise and remove the insert tool.
9. Now you will need to break of the tang from the insert. To do this a LONG set of needle nose pliers will be needed.
10. Make sure and give it another once over with the magnet, especially since the tang will most likely have fallen in the cylinder. Check to see if the insert is about 1mm or 2 down from the top of the cavity. If so, insert spark plug and tighten down. If it's good, your all done. Reassemble and run.
This is my first how to. I hope that I was thorough and specific enough. If I left anything out, feel free to say. I welcome constructive criticism.
. Will cost a couple extra hours , but I'd KNOW there weren't no shavings in the engine. But I'm a worrier 
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