tap a spark plug hole

[skids]

The aluminum heads can adhere to the sparkplug threads, and of course, the steel threads are stronger. Take a good look at the plug and see if there was any aluminum stuck on it. Heck, I guess it doesn't matter...you probably need to tap/clean it out anyway. Use Never-sieze or similar product and never install a plug tighter than it should be (not that YOU did). This is why they put those crush washer on plugs: to make a good seal without the need of excessive torque. I hope you don't have aluminum thread stuck in a valve seat. You may want to check compression prior to rethreading the hole, if the spark plug is in there now.

Originally posted by brock
but when i took the old plug out, it was all the way down. in fact, the bike ran fine till i changed it. now it wont go in barely at all, and of course with it hanging 1/4th of the way out, it's running like pure crap.

i guess what you're saying is probably that if the bad plug was all the way in, then its probably damaged all the way down, including the top.

[prometheus578]

NO, if the old plug was all the way in, then most of the original threads were good. What has happened is that you've now joined the club, of which I'm a life-time member... "SPLASH". The "Stripped PLug And Spark Hole" Club. You should be getting your hat and lapel pin in the mail soon. Again, I can only recommend the reverse tap method, as the bottom threads are still good. Yes, the tap is pricey, but it saves aggravation and gets the job done right; no more cutting cross threads down the whole hole. I would also say that all the plug holes should be done like this, just to give them a good cleaning. When istalling new plugsa, put a little anti-sieze juice on them. helps them go in, and prevents the steel plug from chemically bonding to the aluminum. (I just use a little axle grease)

[rover]

A rich girl uses vaseline, a poor girl uses lard. My girl uses axle grease, and does it twice as hard

[Ken Talbot]

I suppose it might be worthwhile at this point in this thread to clarify that we are talking about two quite different treatments. Or maybe I should say I have been talking about a second treatment.

Much of the discussion has been about simply using a tap to run through the existing threads to clean up some fairly minor damage. The other process is using a much larger, special tap to cut new threads for installing a threaded insert that will establish brand new steel threads for the sparkplug to thread into.

If the cross-threading or over tightening was bad enough in the first place to remove a significant amount of the original aluminum threads from the head, the clean-up tap will not restore what has been lost. In that case, an insert will be needed.

[brock]

thanks for clearing that up. i was just thinking about that just this minute.

I think the damage might be pretty bad. when the plug came out, it had some filings on the threads.

so if it'll do it right, i'll do the more complicated thing. what a pain.

[brock]

OK, i'm confused again. you say insert, is that something that i leave in there forever? so i'm gonna cut a bigger hole, and then put something in there to leave to screw the plug into?

i'm pretty much committed to doing the backward thing (if i can find one at sears/pep boys). how do i get hold of the mac guy?

i just wanna make sure i have a good idea before i begin (this saturday morning, i guess)

thanks again, everyone.

[skids]

As I remember it, you screw the insert onto the spark plug, and then you screw the plug with insert into the newly threaded hole. The insert stays in the hole, the plug is replacable. I think you use a loc tite compound to help the insert stay in the threaded hole and there is never another problem. The threads will be stronger than the original aluminum. You'll be surprized, I think, on just how easy the process is.

Originally posted by brock
OK, i'm confused again. you say insert, is that something that i leave in there forever? so i'm gonna cut a bigger hole, and then put something in there to leave to screw the plug into?

i'm pretty much committed to doing the backward thing (if i can find one at sears/pep boys). how do i get hold of the mac guy?

i just wanna make sure i have a good idea before i begin (this saturday morning, i guess)

thanks again, everyone.

[prometheus578]

Brock: As you can tell, there's a lot of good advice from a lot of good people here with a lot of experience. I think that's great. As for contacting a MAC tool rep., might be in the yellow pages, but I doubt it. Stop in at one or two bike shops or auto shops. One of the mechs there should have one of his cards, mit der phone number. Or at least they can tell you on with day of the week he stops by. That's why Craftsman is so convenient, right down the road, but they don't carry the out of the ordinary stuff that you need once in a while. Or , just occurred to me... Try an internet search... might turn up the name/number of the local rep for your area

[brock]

OK. I'm gonna start today. I think my plan of action is to try to tap it out with the reverse thing if they have it. if by using a regular tap i find that the threads are weakened or just demolished, i'll then go onto a new step, which is the larger tap with the insert, which will be harder and cut a bigger hole, but will cut fresh new strong threads.

sound right to everyone? the mall opens in an hour, so i'm off to sears after breakfast.

thanks again. i'll keep you posted.

[2fast]

Alternate debris removal technique

It may be too late, but just another suggestion for removing the depris as you go. I just did this in the spring. I dropped the exhaust system off, and then just duct taped a shop vac up to the exhaust port. Make sure that you have the piston positioned with the exhaust valve open. This worked very nicely to remove any shavings as they fell into the cylinder. After that, I shot compressed air around in through the spark plug hole with a thin nozzle, with the vac still running. I put it all back to gether and have not had any problems as a result. I did a thread chaser to clean up from a broken off spark plug. I am now a firm believer in anti sieze lube on any dissimilar metals!

[brock]

well, i dont know what i was so scared about, or what i waited so long for. I just brought the tap home, filled up the flutes with grease, ran it down through the hole and now the plug goes in like a dream.

hardest part was finding the right size tap. it cut in there really easily, almost no trouble going at all, it was hard to get it started, since you have to be sure to line it up strait to begin, but once it started going it was no big deal. most of the metal shavings came out in the grease, and another couple bits came out when i shot some compressed air in there. i like the idea of blowing it out the exhaust better. way easier to take the pipe off, than the carbs, etc. also, i couldnt get that t-handle thing on there, since it's plug #2, so i used a rachet, with a 7/16's socket on the end, which fit on perfectly. just careful not to put too much preasure on one side rather than the other.

unfortunately, my old spark plug was all chewed up, so i have to wait till tomorrow to pick up a new one before i can start it up and see how it runs.

thanks again for everyone's good advice. you're all great.