BritBike Forum logo
BritBike Sponsor BritBike Sponsor
BritBike Sponsor BritBike Sponsor
BritBike Sponsor BritBike Sponsor
BritBike Sponsor BritBike Sponsor
The Bonneville Shop BritBike Sponsor
Home | Sponsors, Newsletter | Regalia | Calendar | Bike Project | BritBike Museum
| Spiders Cartoons, | DVD- Manuals & Parts books
Upgrade to: Premium Membership | Premium Life Membership | Vendor Membership | Site Sponsor Membership
ShoutChat Box
Buy BritBike staff a coffee
Buy BritBike's staff a coffeeStill here since 1996 serving BritBike enthusiasts..
Search eBay for motorcycle parts in following countries
Australia, Canada, France, Holland, Italy, United Kingdom, USA
Random Gallery photo
Member Spotlight
darbone85737
darbone85737
Tucson, AZ
Posts: 164
Joined: December 2007
Show All Member Profiles 
Newest Members
Motoplane33, Loop, Filthy pup, Kevin Victor, Soupdragon
10739 Registered Users
Top Posters(30 Days)
franko 126
DavidP 51
reverb 50
Rohan 48
Popular Topics(Views)
925,342 mail-order LSR
Forum Statistics
Forums34
Topics67,189
Posts673,342
Members10,739
Most Online14,755
May 5th, 2019
Who's Online Now
74 registered members (99cyclone), 394 guests, and 839 spiders.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate Thread
Stripped Spark Plug Hole #144229
07/01/08 3:23 pm
07/01/08 3:23 pm
Joined: Nov 2007
Posts: 32
St. Louis, MO
Kevin Lundy Offline OP
BritBike Forum member
Kevin Lundy  Offline OP
BritBike Forum member

Joined: Nov 2007
Posts: 32
St. Louis, MO
I assume I should be looking for a new cylinder head?

Support Your #1 BritBike Forum!

Check out British motorcycles for sale:
British Motorcycles on e-Bay UK, British motorcycles on e-Bay North America


Re: Stripped Spark Plug Hole #144230
07/01/08 3:29 pm
07/01/08 3:29 pm
Joined: Nov 2005
Posts: 746
Reading UK
twinspin Offline
BritBike Forum member
twinspin  Offline
BritBike Forum member

Joined: Nov 2005
Posts: 746
Reading UK
Get a helicoil insert or equivalent. As good as (some say better than) new.


1971 T100R
1970 T120
Re: Stripped Spark Plug Hole #144231
07/01/08 3:46 pm
07/01/08 3:46 pm
Joined: Nov 2007
Posts: 32
St. Louis, MO
Kevin Lundy Offline OP
BritBike Forum member
Kevin Lundy  Offline OP
BritBike Forum member

Joined: Nov 2007
Posts: 32
St. Louis, MO
Thanks. Didn't realize they came in spark plug sizes. Is it possible to do the job without removing the head? I'm a little concerned about chips in the cylinder. Do you think compressed air would remove them sufficiently?

Re: Stripped Spark Plug Hole #144232
07/01/08 4:28 pm
07/01/08 4:28 pm
Joined: Oct 2003
Posts: 11,196
North Georgia, USA
RF Whatley Offline
BritBike Forum member
RF Whatley  Offline
BritBike Forum member

Joined: Oct 2003
Posts: 11,196
North Georgia, USA
It is not necessary to remove the head, but it is highly advisable to have done this job at least 5 times previously and NOT be experimenting on your cyl head. One quick call to a shop for a head in 100% shape will tell you why you can't afford to screw up.

There are a number of tricks an experienced mechanic will use to make sure the new threads are perfectly aligned with the old threads and to keep the chips being generated out of the combustion chamber. Compressed air is one of many of these tricks.

The main lesson you'll want to learn as a regular owner doing his/her own simple repairs is to place 2 drops of motor oil on the spark plug threads EACH time a plug is inserted into the head. If you had done this regularly, then we wouldn't even be discussing 14mm Heli-Coils.

:bigt:


Don't hide 'em, Ride 'em !!

RF Whatley
Cornelia, GA
Re: Stripped Spark Plug Hole #144233
07/01/08 4:35 pm
07/01/08 4:35 pm
Joined: Mar 2005
Posts: 10,232
Boston, Massachusetts
J
John Healy Online content

BritBike Forum member
John Healy  Online Content

BritBike Forum member
J

Joined: Mar 2005
Posts: 10,232
Boston, Massachusetts
Put piston at top dead center at the top of the compression stroke (both valves closed).

Liberally coat the Heli-Coil tap with grease. Fill all of the flutes.

Cut new threads.You will notice most of the chip will be held in the flutes by the grease.

Before installing the coil, put a small amount of grease on the tip of a long thin screw driver. Offer it to the spark plug hole with a light hand to retrieve any chips that may have found their way into the cylinder. Take your time. Try not to get grease on the piston as you do this as the grease will tend to hold onto the chips and make it harder.

After you are sure you got all of the swarf, you can rotate the motor backwards so the piston is at the top of the exhaust stroke and blow air through the inlet port and try to blow any swarf out the exhaust. This is not typically necessary.

Install the heli-coil and remove the tang with a pair of needle nose pliers. I would do this at TDC with both valves closed so that I can fish it out if I drop it. A few small aluminum chips will not harm any thing, but the stainless steel heli-coil tang, that's another story.

Certain Ford motors are prone to spitting out the spark plugs. This process of installing heli-coils while the head is on the motor is done daily in shops that repair Fords.
John


Re: Stripped Spark Plug Hole #144234
07/01/08 7:17 pm
07/01/08 7:17 pm
Joined: Nov 2007
Posts: 32
St. Louis, MO
Kevin Lundy Offline OP
BritBike Forum member
Kevin Lundy  Offline OP
BritBike Forum member

Joined: Nov 2007
Posts: 32
St. Louis, MO
Thanks all for the responses.

I've installed helicoils a couple of times, but never in a cylinder head. May be a good idea to practice on some scrap pieces. I'm pretty sure I already have some pieces of damaged threads on the face of the piston. I will use techniques suggested by John to remove them.

The bike (74 T100R)is my first big project. I tore it down about 13 years ago, and only recently reassembled it. Have not been able to start it yet, but seemed to have been making progress until this setback. Worked through a couple issues such as shorted breaker leads and improper valve timing. I've received much good advice here either directly or reading previous posts. Thanks again.

Kevin

Re: Stripped Spark Plug Hole #144235
07/01/08 7:29 pm
07/01/08 7:29 pm
Joined: Jan 2004
Posts: 4,088
ca, us
D
DMadigan Online content
BritBike Forum member
DMadigan  Online Content
BritBike Forum member
D

Joined: Jan 2004
Posts: 4,088
ca, us
Rather than putting in a Helicoil, I suggest the solid tube insert by KD Tools(?) available at NAPA or PepBoys. Less chance of it unwinding and probably cheaper. To do it right you should set the head up in a mill or drill press to get the angle right and aligned with the original hole. Too easy to mess up by hand drilling. How much is a head worth?

Re: Stripped Spark Plug Hole #144236
07/01/08 8:51 pm
07/01/08 8:51 pm
Joined: Jun 2007
Posts: 6,340
Maui Hawaii
HawaiianTiger Online content
BritBike Forum member
HawaiianTiger  Online Content
BritBike Forum member

Joined: Jun 2007
Posts: 6,340
Maui Hawaii
I like the solid thread inserts myself. With helicoil the same old bad habits that got you into this mess will have you unscrewing the siezed helicoil before long. Always use something on the threads. I use copper grease anti-sieze. It conducts heat nicely.
Bill


Bikes
1974 Commando
1985 Honda Nighthawk 650
1957 Thunderbird/T110 "Black Tiger"
Antique Fans: Loads of Emersons (Two six wingers) plus gyros and orbiters.
Re: Stripped Spark Plug Hole #144237
07/01/08 8:53 pm
07/01/08 8:53 pm
Joined: Nov 2007
Posts: 32
St. Louis, MO
Kevin Lundy Offline OP
BritBike Forum member
Kevin Lundy  Offline OP
BritBike Forum member

Joined: Nov 2007
Posts: 32
St. Louis, MO
You're probably right. It's taken me 13 years to get this far, another couple weeks to get the job done right won't matter. Solid tubes it is. The machinist here at work should be able to help me drill it.

Kevin

Re: Stripped Spark Plug Hole #144238
07/01/08 9:48 pm
07/01/08 9:48 pm
Joined: Apr 2008
Posts: 230
Marblehead,Ma USA
W
Woody1911a1 Offline
BritBike Forum member
Woody1911a1  Offline
BritBike Forum member
W

Joined: Apr 2008
Posts: 230
Marblehead,Ma USA
suprised no one's mentioned timeserts http://www.timesert.com/

seems everytime this discussion comes up the conclusion is that timeserts are the way to go these days .

Re: Stripped Spark Plug Hole #144239
07/02/08 1:11 pm
07/02/08 1:11 pm
Joined: Oct 2004
Posts: 4,425
Melbourne Australia
Tiger Offline
BritBike Forum member
Tiger  Offline
BritBike Forum member

Joined: Oct 2004
Posts: 4,425
Melbourne Australia
Quote
Originally posted by HawaiianTiger:
I like the solid thread inserts myself. With helicoil the same old bad habits that got you into this mess will have you unscrewing the siezed helicoil before long. Always use something on the threads. I use copper grease anti-sieze. It conducts heat nicely.
Bill
I agree but use a nickel based anti-seize, have tried oil/graphite and also copper based anti-seize, after 5K miles the bloody plugs still come out as dry as a witch's tit.

No stripped threads though and torquing new plugs down in [almost] 40 yo threads is an adventure every time.


1969 TR6R
7.62 x 51 is not a maths puzzle.
Re: Stripped Spark Plug Hole #144240
07/02/08 1:20 pm
07/02/08 1:20 pm
Joined: Nov 2007
Posts: 53
central MA
4
44Dwarf Offline
BritBike Forum member
44Dwarf  Offline
BritBike Forum member
4

Joined: Nov 2007
Posts: 53
central MA
Time-sert....keinsert... soild-sert all the same thing a insert with holding pegs.

Anit-seze is a must in Alum just a little you don't want to get any on the insulator of the plug.

44


"Smok'in the competition NOT Tobacco"
"Transplant organs, Don't bury them!"
Re: Stripped Spark Plug Hole #144241
07/02/08 2:10 pm
07/02/08 2:10 pm
Joined: Nov 2007
Posts: 32
St. Louis, MO
Kevin Lundy Offline OP
BritBike Forum member
Kevin Lundy  Offline OP
BritBike Forum member

Joined: Nov 2007
Posts: 32
St. Louis, MO
Thanks for all the input. After watching the video on the website, Timesert seems to be the way to go. I feel pretty confident I can make the repair in-situ. Normally use a little oil on the plugs, but got lazy while doing some compression checks, and didn't take into account the age of the metal or the fact that it probably sat a long time before I got it with plugs in (dissimilar metal problem).

Re: Stripped Spark Plug Hole #144242
07/02/08 4:15 pm
07/02/08 4:15 pm
Joined: Oct 2004
Posts: 452
Beautiful North Carolina
HughdeMann Offline
BritBike Forum member
HughdeMann  Offline
BritBike Forum member

Joined: Oct 2004
Posts: 452
Beautiful North Carolina
I would strongly resist the temptation to use the solid inserts from NAPA. The only thing holding them in place is the knurled edge at the top. You swage them in place after cutting new threads. Once the aluminum head heats up, faster than the insert does, the insert loosens and comes out with the sparkplug.

The cure is to use a coiled metal insert, aka helicoil. However, once the solid insert threads have been cut, the hole is too big for a helicoil. Sound like the voice of experience talking? To make matters worse, NAPA uses two different solid inserts, each having a different threading tap. So if you ever need a new solid insert, it probably won't fit the threads you already have.

A properly inserted helicoil will not come back out with the plug, and being coiled, has enough spring to expand and contract with the head, so it stays tight. It also allows the sparkplug washer to directly contact the head to properly transfer heat.


Hugh: Proof the Dodo is not extinct
1964 Bonneville
A couple others
Re: Stripped Spark Plug Hole #144243
07/02/08 7:55 pm
07/02/08 7:55 pm
Joined: Jan 2004
Posts: 4,088
ca, us
D
DMadigan Online content
BritBike Forum member
DMadigan  Online Content
BritBike Forum member
D

Joined: Jan 2004
Posts: 4,088
ca, us
Time-sert, Keen-sert, solid-sert are not all the same. Time-serts have and unfinished thread on the end that is expanded using a special roll tap. A flair at the top keeps it from moving inward. Keen-sert (I believe) uses the stakes pounded through the threads after insertion. Repeated insertion/removal (especially with carbon in the threads) pushes the stakes against the threads and eventually makes the insert loosen. The solid inserts that I used from NAPA have a flaired edge at the top the sits in a countersink cut in the head by the tap. Yes, Time-serts are better but a kit for a spark plug will probably run at least $100 whereas the NAPA version is about $15. As good? Probably not, but most people are not willing to spend the extra money.
Not a good idea to use anti-seize between the insert and head. Afterall, you do not want it to come out. Calculate the difference in expansion of a 13/16" hole in aluminum and a steel tube with 3/4" I.D. and ~1/16" wall. Not much. If you are worried about it then tap the head when it is at 200 F and put in the insert.
You could also do it right and weld up the head and recut the threads.

Re: Stripped Spark Plug Hole #144244
07/06/08 11:38 pm
07/06/08 11:38 pm
Joined: Feb 2008
Posts: 163
pennsylvania, usa
dale karger Offline
BritBike Forum member
dale karger  Offline
BritBike Forum member

Joined: Feb 2008
Posts: 163
pennsylvania, usa
Helicoil makes a great solid insert. This comes in a kit with the reamer/tap tool and a staking tool as well. On these inserts the top 3 or 4 threads on the outside and diamond cut to grip the head. You run the reamer/tap tool into the head. place grease in the grooves to capture any chips ( I back it out a couple times..clean and regrease). MAKE SURE you are going in straight! That, is the hardest and most difficult part of any helicoil installation. Once you have reamed and tapped the hole clean the thread with denatured alcohol to get the grease residue off. The you simply screw in the appropriate insert ( the kit comes with 3 different lengths ) and once the top thread is flush with the top you place the staking tool in and hit it with a hammer. it will bezel the top over and dig those diamond cuts into the head. IF you so wish you can place hi temp / hi strength loctite on the insert. Although, I never have and have never had one back out. The last thing you do is stake around the outside of the insert about 1/8th inch away about 6 times with a center punch as you would a valve seat. This will push metal against the insert but not interfere with the surface you need for the plugs gasket to seat properly. I have used them all....the KD version is my second favorite choise and use it when room restricts my use of these inserts. This tool set is available from NAPA as well and sells for approx $20 to $30. Like I said I have used hundreds of these inserts on aluminum and cast iron heads and have never had one fail or come out with the plug. I can not say this about the others ...even when oil or anti-sieze was used on the plugs. If you wish i can get you the part # of the kit. If you want to double check to see if any chips got in your head...take a long cotton swap and grease (white lithium)the tip...dab around the inside of the cylinder until you are satisfied. hope this helps.
Dale


76 T140V
79 Honda CB 650
79 Yamaha 175 Enduro
68 Chevy Impala Convert
- - - - - - - - - - - - - - - - -
Re: Stripped Spark Plug Hole #144245
07/07/08 7:05 pm
07/07/08 7:05 pm
Joined: Nov 2007
Posts: 32
St. Louis, MO
Kevin Lundy Offline OP
BritBike Forum member
Kevin Lundy  Offline OP
BritBike Forum member

Joined: Nov 2007
Posts: 32
St. Louis, MO
Thanks Dale et. al. That is exactly what I did. Seemed to work well. In addition to dabbing with cotton swab and grease, I removed exhaust pipe and blew out cylinder with compressed air. Visual inspection with flashlight revealed no chips. Now if I can figure out why it still isn't starting...but that's the subject of another thread.

Kevin


Moderated by  John Healy 

Home | Sponsors | Newsletter | Regalia | Calendar | Bike Project | BritBike Museum | Spiders Cartoons | DVD- Manuals & Parts books
Upgrade to: Premium Membership | Premium Life Membership | Vendor Membership | Site Sponsor Membership
Powered by UBB.threads™ PHP Forum Software 7.7.1