Stripped spark plug hole thread

[lazyeye6]

OK, so a "friend of mine" did some sort of dufus stunt to due with legal cannabis and managed to screw a spark plug cross threaded into the head. Now, this stupid jerk
wants me to fix it for him! What nerve. The damage seems to indicate an insert.
It seems that repair kits for HeliCoil and TimeSert are each a substantial sum. What
am I to think about all of the "fixes" on Tube. I'm leaning towards TimeSert, but
expensive kit for something I'd most likely use only once in my life. Maybe best to
push my- errrrr HIS bike to a repair shop that has a kit. Any opinions?

 

[jbruney]

Take his tools away from him... He's dangerous when armed.

I would certainly allow him to pay a shop for repairing this foul up thereby washing my hands of any chance of enhancing further damage and the off chance of absorbing some blame. Remember Murphy's Law at these times.

 

[lazyeye6]

Be gentle. I will pay for my "friend's" inaptitude, .....this time.

Though I had thought I might get some opinion regarding options.

 

[ashman]

Just buy the repair kit and you will have it when he does it again as its bound to happen again if he don't change his ways, don't blame his dope habit he might just be dangerous with tools even without the dope, not everyone is good with tools or with their hands, I know a lot of people who should never touch tools or work on anything including motorcycles.

Ashley

 

[Scout63]

I rethreaded a stripped XL500 plug hole using a Timesert. Worked very well, but expensive and I haven’t touched the kit in about five years since. I snapped a plug off in my Guzzi restoration and I’m going to swallow my pride and let my machinist fix it. He will be cutting the valve seats and checking the guides anyways.

 

[gortnipper]

If it is only the top couple of threads, you should try and chase it out first before putting a time sert or helicoil in.

Get a good spark plug tap, pull the head and chase it from the inside out.

I have seen that work before. ;-)

 

[lazyeye6]

I rethreaded a stripped XL500 plug hole using a Timesert. Worked very well, but expensive and I haven’t touched the kit in about five years since. I snapped a plug off in my Guzzi restoration and I’m going to swallow my pride and let my machinist fix it. He will be cutting the valve seats and checking the guides anyways.

So.... you interested in selling or renting your kit to me? 14mm. PM me.

 

[Scout63]

PM Sent

So.... you interested in selling or renting your kit to me? 14mm. PM me.

PM sent.

 

[gortnipper]

Do not use a Timesert on a plug hole.

Jim Comstock wrote: "Regular helicoil inserts -not the solid ones- work fine for spark plugs. Just install them 2 or 3 threads deep to keep them from coming out."

This caught my eye because I know a couple of friends who had a problem with the helicoils unscrewing with the spark plug. I am not sure what it means to install them 2 or 3 threads deep, or why this would keep them from coming out with the spark plug?

Stephen Hill

Screw the helicoil in a couple turns after it is flush with the plug seat.
Because the sharp end of the coil will usually dig in a bit so it doesn't come out with the plug.
To help I used to take a punch and mash the thread a little just above the helicoil and use a spot of antiseize on the plug.

Are they perfect, no, but at least they don't crack the head like the solid plug inserts often do.
[And that's why I started doing the stepped Al/bronze inserts.]

https://www.accessnorton.com/NortonCommando/thread-inserts-in-the-norton-head.28897/page-4

You are going to have to pull the head to tap the hole and make sure the swarf is all cleaned out. While it is off, try chasing the threads from the inside > out. This may work if only the top couple threads are damaged, but you will have to insert the plugs with care from then on. But, it leaves you with an intact hole that can be helicoiled later, if necessary.

 

[comnoz]

I hate to pedal work on the list, but send the head to me and I will put in a stepped bronze insert that you will never need to worry about again. Jim

 

[JimNH]

All light aircraft engine spark plug holes have Helicoils from the factory as the plugs are constantly coming in and out and are torqued to 360 lb/in or 30 lb/ft. The price for a 14mm kit will floor you: https://www.aircraft-tool.com/shop/detail.aspx?id=4260-14&AspxAutoDetectCookieSupport=1

Very few engines have 14mm, most 18mm but, if there's an engine shop near you it might be worth a call.

Unless your buddy is an ape he may have just screwed up the first threads and careful application of a thread chaser, available at any parts store, my sort it out.

After choking on the aircraft kit price here's one that you may like better:https://www.oreillyauto.com/detail/...il-m14-1-25-spark-plug-repair-kit/hel0/533414

 

[grandpaul]

I'm not even going to read the other replies.

Timesert.

Period.