Spark Plug Boot question

[jblanken64]

I've been experiencing a rough idle once the bike is warm for a while and I'm still trying to diagnose it. I've read about people trimming their plug wires slightly to get a better connection. Problem is, the spark plug boots on my 2008 seem to be one piece. I haven't tried to force anything apart since I don't want to break it, but if the boots are 2 pieces, how does it separate? I've also read that the other end of the wires can be removed from the coils as well, but I'm not there yet. I sort of dread having to remove those. That doesn't look simple.

Thanks in advance,

Joey.

 

[TownsendsFJR1300]

The parts fisch shows their separate, part #5:

https://www.partzilla.com/parts/search/Yamaha/Motorcycle/2008/FJR1300A+-+FJR13AXCB/ELECTRICAL+1/parts.html

They simply screw onto the wire (regular thread direction). There's a small screw that goes into the wire. While the cap is off, it wouldn't hurt to check resistance.

The caps should fit snug (clockwise) to the wire. If its loose or once un-screwed, if you see any arcing, they should be trimmed.

Once trimmed, gently separate the individual wires so when re-screwing in the cap, the "internal cap screw" goes in the center of the wire (till snug).

I'd also strongly suggest just a little bit of dielectric grease on the edge of the boot where

it touches the valve cover. It makes the install MUCH easier and you'll literally hear and feel a definite snap once the cap is ON the plug...

*When's the last time a TBS was checked/done?

 

[jblanken64]

The parts fisch shows their separate, part #5:
https://www.partzilla.com/parts/search/Yamaha/Motorcycle/2008/FJR1300A+-+FJR13AXCB/ELECTRICAL+1/parts.html

They simply screw onto the wire (regular thread direction). There's a small screw that goes into the wire. While the cap is off, it wouldn't hurt to check resistance.

The caps should fit snug (clockwise) to the wire. If its loose or once un-screwed, if you see any arcing, they should be trimmed.

Once trimmed, gently separate the individual wires so when re-screwing in the cap, the "internal cap screw" goes in the center of the wire (till snug).

I'd also strongly suggest just a little bit of dielectric grease on the edge of the boot where

it touches the valve cover. It makes the install MUCH easier and you'll literally hear and feel a definite snap once the cap is ON the plug...

*When's the last time a TBS was checked/done?

Hmm. That looks like the same drawing that's in the service manual. If I read that correctly, the junction is in the wire, not the boot. I have noticed a sleeve that looks like heat-shrink on the wire. From what I've read earlier, I was under the impression that the boot separated into 2 parts. The wire going into the boot seems molded in, with no give at all.

Joey.

 

[TownsendsFJR1300]

On my FZ6 (I believe the same set up), there is a short rubber boot keeping water out between the wire and the

actual cap. You should be able to spray a little bit of WD40 and work a small screw driver to

break the seal.

Then slip that boot back. Its just sealed up, nice and tight over years of heat cycles..

Just be gentle with the wire itself, you don't to damage that..

There's ONE thin, kinda long screw in the center of the cap that simply threads into the wire..

And yes, on the other end of the cap is a part flat head screwdriver is used to remove. A part (cylindrical, IDK the name) inside along with a spring you can inspect. If resistance is within spec's, that shouldn't be an issue..

 

[jblanken64]

I'll have to take a closer look. I swear I didn't see anything that looked like a seam in the boot.

Thanks,

Joey.

 

[TownsendsFJR1300]

Just to clarify, there is NO seam(or rather,nothing there for you to mess with)

on that short waterproof boot(the short rubber part).

It simply slides over both the wire and the cap itself..

Actually, I think I used silicone spray breaking mine loose.

I shortened mine 1/4", didn't do any good, no arcing seen.

I had some mid RPM's high frequency vibs (engine RPM related, 6-8,000)

.

 

[RossKean]

I'm not sure if you are looking in the right place or not.

On the coil end, the plug wire is permanently attached. The cap and boot is all one rubber piece - separate from the wire. On the plug end, the cap/boot assembly screws onto the plug wire (as TownsendsFJR1300 said). There is sort of a thin threaded spike inside the boot that screws into the wire.

When trimming the wire, don't take too much off. There is very little to spare; especially on the shortest wire closest to the coils.