77 KZ1000 Spark Plugs Question

Would suspect the beginning threads have been crossed and plug forceably turned in part way, which forcing buggered the threads from top of hole downward to some uncertain point.

If continue tapping (chasing) the buggered thread pattern from the top, will cut new threads entire length of hole, also through the original deeper threads. Maybe okay. Maybe not so okay.

Imo should consider using a reverse tap, which begins from the bottom deep end of the spark plug hole from inside the combustion chamber. This will re-tap the original threads on up through the buggered portion lying closer to the top.
Removal of the head is unnecessary.

Some folks apply grease to the tap and work one turn at the time, whereby the "shavings" are trapped in the grease, and the tap may be withdrawn, cleaned, re-greased, and repeat.

Btw, the small magnet may help remove particles that are attracted to the magnet. However, aluminum, stainless steel, and some other metals aren't attracted to a magnet, which would especially apply to aluminum shavings from re-tapping a spark plug hole.

Here's a pic of the reverse tap tool. Sometimes called a back tap.

Good Fortune!

I second Patton's advice. Either use his method or pull the head and get a good look at what is going on. Whatever you do, DO NOT force the plugs in place. That will just about guarantee that you'll strip the threads. Then you will be having the same quandry about aluminum shavings when you are putting helicoils in your head. Not surprising that it happened on 2 and 3. Those are the harder plugs to get to. Also I wouldn't advise you to try and blow anything dropped in you cylinder out through the exhaust. Aluminum shavings are relatively soft and would likely make it out just fine. However, one of those shavings could get hung up on the valve seat, and when the exhaust valve closes it gets hammered to either the seat or the valve. Then you will have a cylinder that won't make compression = engine teardown.

Will a cross threaded hole be obvious??? I checked the plugs they look fine, nothing like they are online... I also peeked in the holes and the threads look fine!!!

Just out of curiosity... :blush:

Plugs... B8ES or something other?
Thread lengths the same as B8's....

Are you positive plugs aren't hitting valves or "holly shit" factor piston domes?

Under ignition plate, ignition advance unit shows TDC 2/3, if so rotate 17mm nut forward direction insuring pistons 2/3 not TDC... Plugs insert fully now?

This is a weird one no doubt...

Patton wrote:

Would suspect the beginning threads have been crossed and plug forceably turned in part way, which forcing buggered the threads from top of hole downward to some uncertain point.

If continue tapping (chasing) the buggered thread pattern from the top, will cut new threads entire length of hole, also through the original deeper threads. Maybe okay. Maybe not so okay.

Interesting. I thought the chasers would not "track" a cross thread pattern which is why they were useful. It's been 30 years since I saw one used so maybe not. The reverse thread cutter sounds like the plan to go with.

The simple solution to aluminum shavings is grease. Just grease up the tap and it's virtually impossible for any shavings to escape, unless there is a large amount. Try it out on a scrap piece of aluminum and you'll see what I mean.

Fixed.... I got the thread chaser that was recommended prior that was the size of the spark hole thread the whole way through without any need to helicoil. Belive it or not there was crud all over the place in those inner threads, probably after years of something!!

Heres how I used the thread chaser for anyone else who may be wondering. Lube it up with some PB buster or some WD40 to break up any nastiness that may be lingering inside the thread hole. Then lube up your tap/chaser. Go in slowly! The moment you feel tension building, start backing out and then go back in again. This is a long process and don't be surprised if it takes you a while. After you get it done, you'll notice that the threads look almost like brand new. (Make sure you also have lots of lube on the chaser - some shavings will stick to the liquid - and a metal brush to keep your tap/chaser clean when you go back in)

DON'T FORGET TO GET THE SHAVINGS OUT! When I got the threads done, I figured there would be shavings in the cylinder... so believe it or not I got a magnet and just fished it around in there and the shavings stuck to it which amazed me because I thought aluminum isn't magnetic. I actually think that the spark hole is some sort of composite...because curly shavings stuck to the magnet. Do this after every chase to keep up on it. Then I just kicked it a few times.

Plugs when all the way in. You'll get some lube in the cylinder head and that will just burn off. You'll also burn off anything at the top of the head where you put your plugs in. It will smoke for about a day...give it some good riding and it'll be okay.

I put iridiums in my bike and it's running great. Although last night the kickstand gave weigh and it toppled over. GOD DARN IT!

Thank you everyone for you help, and I hope my struggles will help out the next person. Remember, take it one step at a time and go in easy! The spark plugs should not be rough going in!!

Usually all you are removing with that tool is built up carbon which there is enough of in the chamber already. The funny part is that carbon is harder than the Aluminum head material. The trick to use is to put some grease into the lands of the cutter. This will hold most of the cut material. Also do the cutting with the piston at TDC. This way it can be vacuumed out more completely.
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