spark plug hole stripped

i took my spark plugs out of my 77 kz650 the other day to clean, and i started to take #4 out. it was in there real tight, and it was hard for me to get out. when i finally got it out i noticed some cracking around the hole and a piece of the engine came out with the plug and the hole is stripped. i had in the shop for maintanence not long ago and when they put the plugs back in they must have torqued that one in so hard that it stripped the hole and cause the cracking. i know that they know they did because plug 3 was barely in the hole.

so, i have couple questions. is there any way to fix this? what should i say to the shop when i go to chew them out? is it safe to ride it like this?

I had the same problem. The previous owner had cross threaded the #4 and I ended up blowing the plug out of the head on the way to work. There are a number of products you can use to install an insert, but it will require taking the head off. Good luck!

what are some of the things that can be used to fix it? and where can i get them from?

any auto parts store should have a heil-coil thread repair insert kit.i did the same to my 77650 about a month ago.you will need a 5/8 drill bit and a steady hand.you really should remove the head to do it but it is not 100% nessessary.you will drop shavings in the motor if you don't. i did not remove my head and used a strong shop vac to get them all out. but one warning! make sure both valves are closed or you will nick one of them with the drill bit.i found that out the hard way.dumb mistake!but think of it this way, if you have to pull the head, now you can always install the 700 or 810 kit and cams i know you want to.perfect excause, my wife bought it that it won't run right now and it will die a slow painful death unless i rebuild the upper half now.so now i ordered a kit and a new ring for her. we all have to compromise sometimes.good luck and let us know how it turnes out for you. sorry,it's not a heli coil. it's called save a thread.

Post edited by: kawsakiman, at: 2006/06/21 18:27

SNAP ON makes a tool that uses compressed air to blow out the shavings while you retap the hole for a heli coil insert.it is expensive tool for 1 use.
I have done it caveman style and used a lot of clean grease on and in the helicoil tap. you remove , clean and regrease the tap like every quarter or half turn to get the metal out. patience and persistance. Be sure get the piston near top center going on the exaust event before cutting metal. turn crank to where the exaust valve is wide open use some gasoline and compressed air into the compression chamber to get shavings out the ex pipe. dry the new threads. use red loctite when installing the insert. let loctite fully cure before starting the engine. then hope for the best when you start it up. I have had success doing it this way. not fun or cool.

Here is a site that shows a tool that does not require a drill. I used a similar tool and it will use the existing threads and cuts new ones for the insert.

www.timesert.com/html/sparkplug.html

Most companies that make thread repair inserts sell 14mm inserts to repair spark plug holes. The BEST is a Timesert because it has a mechanical lock. Helicoil is a wire coil that can and will come out when you remove a spark plug. Somewhere in the middle is a solid insert like the ones that NAPA sells. It is retained by anaerobic adhesive like red loctite. www.z1enterprises.com can get you a Timesert plug repair kit as you will also need the tap and install tool. The NAPA brand inserts come in 1/2" and 3/4" if memory serves and you need to cut the 3/4" insert to make it the correct length. You can cut it with a hack saw or small cut off wheel easily. The main issue you will run into is that all of them require threads be cut in the existing hole so their insert can be screwed into place. You will get bunches of shavings that will drop down a plug hole when you are cutting the threads for the insert so I highly recommend you remove the cylinder head (buy a new gasket) and do the job with the head off the bike. Some folks have claimed luck by vacuuming out the combustion chamber or coating the tap with grease to catch shavings. I am not hopeful about either way of ridding the combustion chamber of metal bits. The bits will not be magnetic no a magnetic is out. The tap to cut the threads for a NAPA insert takes a couple of hours to get started and get the thread cut... it is not an easy job. You might want to take the head to a machine shop along with the proper insert and let them help you. You can also try a plug thread chase. They have them in 14mm with the correct thread and these things are supposed to recut and clean the old thread. I have found them to be fairly useless...

i just wanted to show you guys what the spark plug hole looks like. i don't think helicoiling will fix it. to me it looks like the only way to fix it is to replace the entire head. am i right? or does anybody else have any ideas? by the way the shop that did this said they would repair it free of charge.

Post edited by: mjwriz, at: 2006/06/21 16:51

Post edited by: mjwriz, at: 2006/06/21 16:46

That is a piece of the engine missing.

Post edited by: mjwriz, at: 2006/06/21 16:54

tough call... but if they pay get it welded up and surfaced. teflon tape? JB weld? no I'm foolin sorry to see these things

dont let hercules tighten your plugs any more.

that's a tough one . there is/was a 650 head on e-bay for $19.99.don't know if it's still there.