Spark plug inserts -another al/bronze video (2015)

Status
Not open for further replies.
comnoz

comnoz

Joined
Dec 10, 2008
Messages
7,253
Country flag
Spark plug inserts.
There are two common types. The helical insert which may be a bit shaky.

Spark plug inserts -another al/bronze video (2015)


Or the thick walled insert which is very strong but causes problems with the Norton valve seat.

Spark plug inserts -another al/bronze video (2015)


Spark plug inserts -another al/bronze video (2015)


Here is what I do. Jim

[video][/video]
 
Last edited:
Several years ago I used a Helicoil insert repair kit. Came out with the plug first time I removed it.
Because of the damage had to use a Time-sert Big Sert.
It's right on the seat as you can see.
Spark plug inserts -another al/bronze video (2015)

Lightly lapped the valve and checked for sealing, which was good.
It's stayed in place during plug changes.
So far it runs fine, keeping my fingers crossed.
Wish I would have known about your process at the time.
 
htown16 said:
Several years ago I used a Helicoil insert repair kit. Came out with the plug first time I removed it.
Because of the damage had to use a Time-sert Big Sert.
It's right on the seat as you can see.
Spark plug inserts -another al/bronze video (2015)

Lightly lapped the valve and checked for sealing, which was good.
It's stayed in place during plug changes.
So far it runs fine, keeping my fingers crossed.
Wish I would have known about your process at the time.
Click to expand...

As long as it's not leaking you will probably be OK. I have seen them with a crack into the big insert hole that eroded under the seat and I couldn't figure out why I couldn't hold a vacuum when checking the valve seal -until I pulled the seat. Jim
 
Would it make any sense to use a smaller-thread spark plug? The plugs in my ZX-14 are miniscule compared to the plugs that go in the Norton, which are very similar to the plugs I use in my lawnmower.
 
COMNOZ

You are the Norton surgeon!
Your mill is your scalpel.
You make it seem so easy. That’s the mark of a true professional.
Great stuff to watch.
 
Danno said:
Would it make any sense to use a smaller-thread spark plug? The plugs in my ZX-14 are miniscule compared to the plugs that go in the Norton, which are very similar to the plugs I use in my lawnmower.
Click to expand...

I used to make a slightly oversize insert for a 14mm plug hole that held a 10mm spark plug. That would fix a plug hole that was only worn but not stripped. That is what has been in my bike for years with no problems.

They can also be made to fit in a hole that was tapped with a helical insert tap to repair one that has stripped.

Nobody showed much interest in the small plug so I haven't made any in quite some time. Jim
 
comnoz said:
Danno said:
Would it make any sense to use a smaller-thread spark plug? The plugs in my ZX-14 are miniscule compared to the plugs that go in the Norton, which are very similar to the plugs I use in my lawnmower.
Click to expand...

I used to make a slightly oversize insert for a 14mm plug hole that held a 10mm spark plug. That would fix a plug hole that was only worn but not stripped. That is what has been in my bike for years with no problems.

They can also be made to fit in a hole that was tapped with a helical insert tap to repair one that has stripped.

Nobody showed much interest in the small plug so I haven't made any in quite some time. Jim
Click to expand...

I guess it wouldn't matter much with regards to the proximity of the repair to the valve seat; the original opening is still the same.
 
Danno said:
comnoz said:
Danno said:
Would it make any sense to use a smaller-thread spark plug? The plugs in my ZX-14 are miniscule compared to the plugs that go in the Norton, which are very similar to the plugs I use in my lawnmower.
Click to expand...

I used to make a slightly oversize insert for a 14mm plug hole that held a 10mm spark plug. That would fix a plug hole that was only worn but not stripped. That is what has been in my bike for years with no problems.

They can also be made to fit in a hole that was tapped with a helical insert tap to repair one that has stripped.

Nobody showed much interest in the small plug so I haven't made any in quite some time. Jim
Click to expand...

I guess it wouldn't matter much with regards to the proximity of the repair to the valve seat; the original opening is still the same.
Click to expand...

Yes, but the original opening or the opening made when you tap for a helical insert is not a problem with the proximately of the seat. So yes a small plug insert is a viable option -and one you wouldn't need to send the head to me to install. Jim
 
Always fascinating to see how you rig up for repeat business but did ya have to make us sit around for the whole slow process? Just teasing and to say since you mix up JBW more frequently than me who detests time wasted as a mechanic - I found a nice size/shape container i can criss-cross with duct tape and place a disc or ring super magnet under the container which the steel dust holds up to bottom and magnet piles the mix into a raised button instead of flowing into a layer, so can mix smaller amounts well w/o as much waste - when done toss the tape saving the handy mixer. Btw is there a favorite plug anti-seeze? Hope hobot use of JBW don't smear your reputation too.
 
I prefer the copper anti-seize for plugs.
The type that is designed to use on aluminum electrical connections in big fuse panels. Just a little dab will do ya. Jim
 
Intriguing machining process that has moved on massively since I was an apprentice. My question is, how do you machine the threads on the two different diameters of the insert, to be in exactly the right relative position as the two threads in the head?
 
gripper said:
Intriguing machining process that has moved on massively since I was an apprentice. My question is, how do you machine the threads on the two different diameters of the insert, to be in exactly the right relative position as the two threads in the head?
Click to expand...

It's easy with CNC. You just start the threads from the same angle and height.

The trick part is the small part of the thread. The thread on the ID of small end is machined right down the center of the thread on the OD. That allows for a wall thickness of only .5mm for the last 7mm. Jim
 
The trick part is the small part of the thread. The thread on the ID of small end is machined right down the center of the thread on the OD. That allows for a wall thickness of only .5mm for the last 7mm. Jim
Click to expand...

I have heard of thread inserts from Mercedes or BMW that had an internal thread that followed exactly the external thread making them stronger and thinner than a Heli Coil. My question is: How do you support the piece while you cut the second thread? Do you do the outside first and then thread it into something before cutting the inner thread?
 
motorson said:
I have heard of thread inserts from Mercedes or BMW that had an internal thread that followed exactly the external thread making them stronger and thinner than a Heli Coil. My question is: How do you support the piece while you cut the second thread? Do you do the outside first and then thread it into something before cutting the inner thread?
Click to expand...

The inner thread is cut after the insert is installed and torqued into the head.
The inner thread is cut to follow the outer thread so the wall thickness is kept to a minimum -like Mercedes.
 
Looks like even if you have good threads now, sooner or later (and probably when you least need it) one will fail. So it would be sensible to fit some sort of 14mm to 10mm bronze conversion bush which can be fitted without special equipment. How about it Jim ? :) Perhaps they could have a snap off hexagon head which brakes away once the insert is in deep enough.

cliffa
 
cliffa said:
Looks like even if you have good threads now, sooner or later (and probably when you least need it) one will fail. So it would be sensible to fit some sort of 14mm to 10mm bronze conversion bush which can be fitted without special equipment. How about it Jim ? :) Perhaps they could have a snap off hexagon head which brakes away once the insert is in deep enough.

cliffa
Click to expand...


I made some several years ago. I just cut them with the top couple threads not cut to full depth. Then a bolt, nut and flatwasher were used to install them. They got tight the last couple turns and then stop when the flatwasher contacts the head. I used JB weld to install them.

I have been running them in my bike for a long time. I prefer the 10mm plugs. They seem to get the best/latest technology first.

I got some bad feedback on them so I have never made any more. People were not used to tightening a 10mm plug so they often broke them off. Plus the spark plug caps to fit a 10mm plug used to be tough to come by. Not so much anymore. Jim
 
Jim,
Is there an exact equivalent 10 or 12mm plug (heat range) to replace a 14mm or does it require a bit of guess work?
Martyn.
 
Matchless said:
Jim,
Is there an exact equivalent 10 or 12mm plug (heat range) to replace a 14mm or does it require a bit of guess work?
Martyn.
Click to expand...

The heat ranges are numbered the same -at least with NGK they are.

I believe they can be had from CR6EK to CR11EK. Low compression motors would be good with CR7EK. High compression motors would use CR8EK . Race motors would use a CR9EK [or colder].

I use a CR10EK with electronic engine control.

There are also versions with multiple ground electrodes or Iridium electrodes.
 
comnoz said:
I got some bad feedback on them so I have never made any more. People were not used to tightening a 10mm plug so they often broke them off.
Click to expand...


I guess they are the same folks who stripped their threads.

I'm sure you knew this was coming, but any chance of making more Jim?
 
Status
Not open for further replies.

Similar threads

T
  • Locked
Spark Plug insert
Replies
5
Views
939
splatt
S
Back
Top