Stripped Spark Plug Hole

[bcware]

I've been spending a lot of time trying to tune my bike and after removing and replacing the plugs dozens of times it looks like I finally inserted one poorly and ended up stripping the threads on the engine.

I figure a tap and die set would work, but I don't know what size to use and it makes me a little nervous. I am worried about messing the threads up even more.

Any advice?

78 2e by the way

 

[hmusket]

I cross threaded the spark plug on my first bike, a 1980 Suzuki GS450, and ended up using a helicoil kit to repair. Bike seemed to work ok after.

Heres a google search link:
http://www.google.com/search?client...=1&bav=on.2,or.r_gc.r_pw.&fp=668845393480168f

Also you may only have to clean the threads up.

Found a thread on the xs650 forum, skip to the middle where Travis is talking about threads (spark plug type). The fellow asking the question had an XS400 and might be on this forum and might pipe in.

http://www.xs650.com/forum/showthread.php?t=5

 

[bcware]

The threads are pretty bad. When I removed the plug there was a lot of aluminum in the threads of the plug; it looks mangled.

I am pretty upset about this because I have spent so much time rebuilding everything and I am very near completion. Now it looks like I will have to tear the entire thing down again to get the heads off.

Seriously considering just giving up and buying a new bike.

 

[HoughMade]

I was able to just chase the threads with a 14mm chase and so far, so good.

 

[cafedan]

it sounds like you have a few options available, hang in there!

 

[bcware]

How do I figure out what size the plug is and the thread type? I don't think a tap alone is going to work, too much material is gone. I think I am going to have to use an insert but I am not confident about doing this sort of thing.

 

[hmusket]

Like Cafedan said:

it sounds like you have a few options available, hang in there!

I know you're disappointed because of all the work you've put in the bike to have something like this happen. The work you've done on your bike, and your posts and explanations have been positive to a lot of people on this forum. Thanks.

Back in 1980 with my first bike, when what happened to you, happened to me, the spark plug all of a sudden popped out of the engine and I and my soon to be wife pushed it over 2 miles home. Talked to a few fellows with more experience than me, went to an auto store, got the helicoil kit, was careful, followed the instructions and advice, and I was back on the road.

If I remember correctly I didn't take the heads off (I didn't even know what a head was, thats how mechanically declined I was), I just stuffed something in the spark plug hole, drilled and inserted the helicoil, I think 14mm, but take a spark plug with you to the auto store.

 

[bcware]

I am going to head out to the store and pick up a tap and repair kit; I'll try and clean up the threads first before installing a coil.

Pro tip: never install a plug with a socket wrench initially; always start it with your fingers. If the plug is too hot to handle just wait. My impatience has taught me a lesson!

Wish me luck. I suppose this is a good learning experience if nothing else.

Does anyone have any tips for guiding the tap squarely into the engine? I have seen special tap guides sold online, but I am doubting they have such a thing in the store for every given size.

Pics added for giggles.

 

[staycryptic]

You're pulling the head off, right?

This reaallllyy shouldn't be done with the motor still together. Any little scrap of metal that falls into that hole will guarantee you're in for more work in about 100 miles.

 

[dO-bOy]

wow and here we were being all confident inspiring

i've cleaned up threads on my cars allll the time. i have the misfortune of ALWAYS buying cars that people overtorque their bolts and they overtorque their spark plugs too. i've never had to use an helicoil quite yet. i've actually never even used a tap! old spark plugs work fine because they're still harder than aluminum (i really don't endorse this method though, its pretty ghetto) here are my tips...


- make sure the motor is bone dry inside. i guess you don't have the option now, but i usually run the engine really hot and hard, then shut down. reason for this is i believe all the gasoline will burn or evaporate. or just let it sit for a few days lor longer. reason for this is wetness will cause the metal pieces to want to stick.

- i have the piston at TDC so there's less area for the material to go. be careful of this though if you're using a drill to put a helicoil in! don't wanna drill the top of the piston hahaha

- lotsa compressed air. best is one of those long thin wands that have a trigger on them for blowing compressed air. blow for as long as you feel to get any shards out and exercise every angle. blowing into the hole from the outside works. blowing from the inside works. you just want to clear that chamber out as best as possible!

matter of fact, my xs400 had a mildly mangled spark plug hole on the right. i used metal picks with angles on the them to manually clear and form the threads again before running a spark plug through veerrryyy slowly and carefully. you want to advance very slowly. like go in 1 turn, take it out, go in 2 turns, take it out. just advance as much as you feel is ok. sometimes you hit an ok area. some areas take a few knacks at it. I don't even have compressed air at home so i bought a can of that keyboard blower cleaners things!

sorry for the rambling, but don't lose faith! all's not lost. wish you were local because i'd give you a hand.

 

[drewpy]

A bodge before you do anything else is to grind a couple of grooves (north to south) in an old spark plug. this becomes a thread catcher.

helicoil kits can be inserted with the engine in situ and helicoils are recommended in high performance engines as the steel grips the spark threads better.

 

[bentwrench]

If you aren't sure of the thread, I usually take the unknown item to a hardware store, and try various nuts or bolts until one fits. Check out the size of what fit, and voila, you have an ID.

Good luck. Don't give up - better the devil you know than the devil you don't. Consider this a learning experience.

 

[bcware]

I picked up a kit at the auto parts store and the process ended up being quite easy. The style insert I got is a full sleeve, not just a coiled wire (similar to a time-sert). The insert has knurled edges at the top that expand when the special tool is inserted and pounded with a hammer. The advantage of this kit is that it does not have a tang that needs to be broken off like a heli coil and thus the risk of a hard piece of metal ending up in the engine is reduced. Unlike a time-sert I do not have to drill out a recessed lip into the heads in order to get the sleeve to sit flush.

I tried chasing the old threads first, but they were too far gone. The new tap in the kit has a smaller chasing tip which squares the tap very nicely. I coated the tap with heavy grease and nearly all of the metal shavings and the grease was funneled out of the hole.

To further remove metal I have a very small magnetic wand for picking up screws in addition to a shop vac with a small flexible hose that I taped on the end. Q-tips were used for cleaning up shavings in and around the new threads. I will blow out the cylinder with compressed air and do additional cleaning tomorrow.

The sleeve gets coated with rtv silicone before being inserted, so I need to wait 24 hours for it to cure before I can try and start the engine.

I am sure I will not be able to remove 100% of the shavings, but I can probably come close. The soft aluminum (aluminium) shavings practically disintegrate between my fingers, so I am not too worried about damage, but I am sure there is risk involved.

Oh, and while I was shopping in the store some guy decided he would back up into my car and it turns out he doesn't have insurance; SWEET.

 

[OliverB]

Sounds like you made a decent repair. Great work. See how much you are learning! LOL Sorry about the fender bender. Sometimes it seems like you just can't win for loosing.

 

[lhaolpa]

I always heard that you're not supposed to remove a spark plug from a hot aluminum head.That also applies to bolts in non-sleeved holes.I rebuilt many VW's and the headbolts almost always needed 'serts.I keep a thread chaser in my tool box,and always use anti-seize on plug threads. lha

 

[dO-bOy]

i was taught to take plugs out when hot? lol

 

[lhaolpa]

Keep doing that,but first stock up on heli-coils,or your preferred fix. Of course,if you repair with the sleeves,you'll only have to do it once,as they'll not easily strip. lha

 

[cafedan]

glad you got it fixed up. now ill know what to do if that happens to me. sorry about the bender though, that no fun.

 

[ghoulgang]

How did this turn out BC? Did it work in the end? Same thing just happened to me...

 

[Scorpio1963]

I dont think BC is around,He hasnt posted in a couple of months.