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Replacing the TBR7’s spark plug boot is pretty straightforward, and I can’t figure out why I waited this long to go through the steps of changing the whole ignition system. In this post, I plan only to cover the TBR7’s spark plug boot replacement since it’s quick and easy, and I feel every new TBR7 owner would want to do this right away. Previous Post: TBR7’s New MSD Spark Plug Boots Arrived!
Changing the TBR7’s spark plug boot should be done with changing the spark plug. For reasons that will reveal themselves as I go along, and just in case, I will cover again at the end. My previous post about upgrading the TBR7’s spark plug ( Finally, Did The TBR7 Spark Plug Upgrade. ).
Let’s get the background information out of the way first. I didn’t just want to start yanking at wires( Why Should You Grasp The Spark Plug Boot Instead Of The Wire ) that carry high voltage when running. I know the bike was off when I changed, but I don’t want to create bad habits now.
As a middle-aged man, I still remember shop safety talks, and I wear real safety glasses( Safety Glasses With Readers ) when I work on my TBR7, but enough of this, let’s move on.
Please work in a safe environment, motorcycles are heavy and contain flammable liquids. My 7 Motorcycle Garage Safety Rules – FAQ
What Does A Spark Plug Boot Do?
A spark plug boot functions are straightforward; it protects the connection point between the spark plug ignition wire and the spark plug.
Note, I do not include the terminal connections as a function of the spark plug boot even though they are housed within the spark plug boot. That is part of the ignition system(spark plug, coil, wire, etc.)
BTW, I upgraded the TBR7 Motorcycle’s spark plug a while back; if you want to read about it: Finally, Did The TBR7 Spark Plug Upgrade.
When Should Spark Plug Boots Be Replaced?
An honest general quick answer: when the spark plug boots no longer function as they should.
Boots should help hold the end of the spark plug ignition wire to the spark plug.
Boots should prevent dirt and moisture from getting to the spark plug terminal.
If they don’t do this, then they are “broken.”
How Do You Fix A Broken Spark Plug Boot?
Easy answer: Replace the spark plug boot.
I will cover how I quickly replaced my stock spark plug boot for an MSD spark plug boot.
Is My TBR7 Spark Plug Boot Broken?
No. It is still functioning. Just not happy with the stock TBR7 spark plug boot and decided to change it. I hope to get better performance out of the TBR7’s engine and get rid of the ugly ‘tin-can’ stock spark plug boot. I cover it more in a previous post: (TBR7 Motorcycle Spark Plug Boot Upgrade?).
Are Spark Plug Boots Expensive To Replace?
I went with MSD spark plug boots; I got two in the same package for a low price. Check for current prices here: MSD 3311 Spark Plug Wire Boot and Terminal, (Set of 2).
What Tools Do I Need To Change A Spark Plug Boot?
Looking back, if not for the TBR7 stock spark plug boot being a resister-type boot, I might have been able to slip off the boot and slide on another boot.
However, with the stock spark plug wire terminal and spark plug boot being integrated, I have to crimp on a new spark plug wire terminal. So the tools I used:
- Wire Cutters.
- Needle-nose pliers.
FYI: Building My List of Must-Have Tools For Motorcycle Owners
What Materials Do I Need To Change A Spark Plug Boot?
I used dielectric grease to slide the new spark plug terminal into the new spark plug boot.
I use anti-seize on my spark plug threads as a general step for any metal-to-metal contact.
I will cover this in the installation steps below.
How Do You Change A Spark Plug Boot?
On the TBR7 motorcycle, it’s real easy, and I will go through the quick steps here.
Quick Spark Plug Wire / Boot Operational Steps.
You should grasp the boot of the spark plug wire and not the cable itself when removing the wire.
Hidden inside the boot are the actual electrical connections of the ignition system. There is a point of contact to the spark plug terminal and a thin wife within the spark plug wire.
If you pull on the wire, you might break the thin ignition wire (designed for electrical purposes, not structural) or damage the spark plug wire terminal.
So you firmly grasp the boot and twist spark plug boots before removing them.
The twisting helps remove any adhesion between the boot and the spark plug insulator or terminal that might have occurred with the heating and cooling of the engine.
Be careful; I planned to replace the stock TBR7 resister-type spark plug boot with a non-resistor-type spark plug boot. I plan to replace the ignition system later, but for now, I’m just documenting how I replaced the boot. My plan is not to damage the stock spark plug wire.
TBR7 Spark Plug Boot Change Side Notes.
These are very important since the stock TBR7 spark plug, because of the stock spark plug boot than any care spark plug and boot I changed in the past.
What Is A Spark Plug Terminal?
This part is the little conductive (metal) tip of the spark plug at the very end of the spark plug insulator. The spark plug wire makes electrical/physical contact with the spark plug.
Does Spark Plug Terminal Type Matter?
YES!
The terminal is where the spark plug wire and spark plug come together. An excellent electrical/physical connection is needed, so energy to jump gaps is spent in the engine cylinder, not outside it.
A good connection means more energy delivered where it should be in the fuel/air mixture of the engine.
Why Do I Mention This?
The spark plug terminal for the stock TBR7 spark plug boot is very thin; when I upgraded my spark plug (Finally, Did The TBR7 Spark Plug Upgrade.), I removed the tiny rounded spark plug terminal to expose the thin post for my TBR7’s spark plug boot connection.
I kept this part in my ratchet set case, which is needed now.
The MSD spark plug terminal(came with the MSD package) is designed for the fat round spark plug terminal.
If you have a mismatch, thin to thick, you will have connection issues and rob your engine of power or just operating. Please pay attention to the terminal connections.
An essential point, if you have the stock spark plug in your TBR7, it came with a skinny straight post. I did NOT come with a rounded spark plug terminal that fit the MSD spark plug boot. This moment would be an excellent time to upgrade your spark plug. I upgraded to the NGK (Finally, Did The TBR7 Spark Plug Upgrade.)
OK, Enough Backstory, Let’s Get Down To Business!
1.- Remove The Stock TBR7 Spark Plug Boot.
Grasp the boot, slightly twisting to break any adhesion, pull on the boot straight out away from the spark plug.
2.- Uninstall The Stock TBR7 Spark Plug Boot.
The stock boot is actually ‘screwed’ into the spark plug wire. Hold the spark plug wire, face the boot, rotate the boot counter-clockwise, unscrew the boot.
3.- Clean End Of Spark Plug Wire.
I cut off about 1/4″ of spark plug wire to get a clean end, and I was unsure if the stock spark plug boot screw damaged any wire threads. So I cut to be sure.
4.- Remove Spark Plug Wire Jacket.
I cut at least 1/4 inches of the jacket off. I didn’t use a wire stripper, which could have made it easier, but I used my wire cutters. I nibbled a little around the jacket and pulled it off. The wire jacket came off without damaging the ignition wire.
5.- Crimp-On New Spark Plug Wire Terminal.
I rotated the spark plug wire and the new terminal to have a good angle facing the engine’s spark plug, so when finally connecting the spark plug boot, it minimized the twisting of the spark plug wire.
I inserted the wire into the small crimp area and the jacket into the large crimp area. I ensured I saw wire extend past the small crimp area for 100% contact, and the jacket extended past the large crimp area for good mechanical strength.
I then used my needle nose pliers(and cutters) to crimp the spark plug crimps onto the spark plug. Then used my needed nose pliers to crimp the smaller conductor crimps, giving a slight pull on the terminal to ensure a good mechanical connection.
6.- Insert New Spark Plug Wire Terminal Into Boot.
I used dielectric grease to help with this step—a lightly lubing terminal and inlet to the spark plug boot.
Once inserted, look into the boot end, and ensure the proper positioning of the spark plug wire to accept the spark plug terminal. You should see it look like it’s “cupped.”
7.- Check And Replace Spark Plug Terminal(Straight Post Converted Into Round Post).
The stock spark plug had a thin straight terminal, as I stated before, this is standard for the stock TBR7 spark plug boot.
I upgraded from the stock TBR7 spark plug to the NGK spark plug ( Did The TBR7 Spark Plug Upgrade ) and removed the rounded end. I stored the rounded end away for later upgrades. Important thing I found it again. 😀
If you are using a newly upgraded spark plug with a rounded terminal end already installed, you can skip the rest of this step.
I had to ‘fix’ my upgraded NGK spark plug:
I removed my upgraded NGK spark plug to examine, clean, and re-install the rounded end. If you have already upgraded, these steps might help you.
a.- Cleaned spark plug with a wire brush.
b.- tiny-bit anti-seize on the terminal.
c.- finger threaded rounded terminal on the spark plug.
c.- Used needle-nose pliers to finish screwing on the round terminal gently.
8.- Install Spark Plug.
I used this time to clean the spark plug gap and re-size the gap, per the TBR7 Owner’s Manual: 0.6mm-0.8mm.
I applied a tiny amount of anti-seize on my spark plug threads.
Once the spark plug is installed, hand threaded first to prevent cross-threading, and then snugged up with a spark plug wrench, I moved on.
9.- Install New Spark Plug Boot.
Insert spark plug boot directly and push it till it ‘clicks’ into place.
Spark plug boot should resist gentile pulling, and this resistance is a good indication of an excellent physical and electrical connection.
10.- Test Your Work!
I ran my motorcycle; the engine sounded ‘good.’ Unsure about the power increase, but it sounded good, and it looked good. Face it, I was not too fond of the cheap look of the stock TBR7 spark plug boot, and it was more difficult to remove than the new MSD spark plug boot.
So I am happy with my TBR7 motorcycle. 😀
Thanks for reading along, and feel free to leave comments.
Ride Safe, Ride Fun!
