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Spark Plug Caps

MotoG5

MotoG5

Tuned and Synch'ed
Joined
Oct 10, 2012
Messages
80
Location
Valley, NE
Hi All,
Just wondering how everyone feels about the plug cap issue. I have seen this first hand now but not on my bike. Easy roadside temporary fix with tape. I suppose any new OEM replacement from Guzzi would be prone to the same failure. So, what do you think. Just trust to luck and carry some tape, purchase and carry an OEM Guzzi cap or replace with aftermarket NGK caps? Trying to decide how I am going to handle this.
 
Had the exact same issue yesterday, covered the HT lead and head with electrical spray and tape sorted that sorted it. Will look for siutable replacement. FYI, when the spark starts arcing across the tappet cover head, it affects the speedo cluster. The thing goes completely blank!!
 
I got stranded a couple of weeks ago because of this. The left cylinder started to misfire. It got worse and finally I had to stop. I was stranded... And started to curse the Goose for letting me down! :angry:
Well... Calmed down after a few minutes... ;)
Luckily it happened not far away from home. And lucky me I had a couple of NGK spark plug caps in my garage. Called my eldest son and a few minutes later he came with them and the tools I needed for the job to swap the stock caps with the one from NGK.

I cut the lead at the end, screwed on the NGK caps and pushed it in place onto the spark plug. Voila! problem solved!
And no problems with the length on either leads.

The Guzzi importer here in Norway have confirmed that they will send me a new set of cables under warranty. The probable cause for the spark plug failure is the way the Guzzi mechanic loosened the cable from the plug. He couldn't remember how he did it, he told me, but I' m pretty sure that he pulled loose the cable from the plug instead of using a screwdriver in that opening in front of the cylinder and from here push the cap and lead loose from the plug with the end of the screwdriver.
That's the only secure way to loosen the cap and lead.

As a precaution measure to avoid being stranded like this again, I ordered NGK Power Cables X4K from Webike in Japan.
Works like a charm! All you have to do is cut it to the length you need for the Goose and swap the terminal/cable shoe for the coil end from the stock leads.
 
I also have a system for when I do valve lash checks... I simply remove the valve cover bolts and remove the valve cover taking the cap off with it, which pulls it off using the plug boot sealing flange. If you're just pulling the caps for plug replacement, then the above notes apply.
 
Thanks for the input guys. I really like the NGK PCX4K kits but I am too strapped to go the bucks. I am already looking at a new tire before I leave next month for a rally in Ontario and I need my bike stash cash for the that and the trip. So I think I will pick up a couple of the NGK SBO5E caps at a few bucks each and have them handy for a possible road repair. I have taken an look at the replacement process here in the list and it seems a good way to insure that a shorted plug cap at least will not be too big a problem. Who knows the stock units may last some time, not all of them are going bad. But enough of them have that it would be foolish to just ignore it.
 
Spoke to the dealer today and apparently the reason they're going is because people keep pulling the things off from the top... Apparently they are supposed to be wedged off. My plugs started giving me shit again today so I removed the rectangular cover over the cap and taped both up with insulation tape. The rectangular cover force's the wire into a very awkward spot hence the ease in which is shorts out. I have covered 150 miles today with the cover's off and the leads taped up and it went perfectly fine.
Attached 2 photos of "wedge" holes..... :blink:

MG Dealer UK - 1x standard suppressor cap + lead £29-00 ($44)
 
It was my bike that MotoG5 observed (and diagnosed, BTW--Thanks!). I replaced the electrical tape with silicone "Rescue Tape" because the thought the elec tape would be affected by engine heat and water. I ordered the OEM replacement cap and I plan to carry some silicone tape and a spare cap with me.

I have researched this issue quite a bit and cant find a definite cause, whether it's inherent in the design or it's the the way the plug caps are removed. I'll just carry a spare and some silicone tape and hope for the best.
 
I had the plug lead break on my bike a couple of weeks ago. It would run as long as I kept it above four grand. Try splitting lanes and keeping the rpm up there! I had a 70 mile ride home when the connector broke. I pulled the lead off and the little tube connector that goes over the plug was still on the plug. I cut the connector off and found the resistor was broken at the end where the tube was attached was attached. There is a partial ring around the outside of the tube that has a couple of dimples in it and the ring is spring loaded to hold the tube on the plug I had a hell of a time getting the tube off the plug. that thing is far too tight and, IMHO, that is what is causing these connectors to break. I don't think it matters whether you pull them from the top or push from the bottom. The ring isn't going to let go! It's a lousy design. The bad part about it is that there is no way to fix it without tearing the rubber cover off! I would definitely get another one as a spare and carry it with you. Even another type NGK would be OK or better.
Bare
 
The question is not if it will happen but when. My left cylinder went dead in North Dakota on my way from NC to Alaska. I was able to limp along after pushing harder on the cap, but it still ran poorly. I eventually found the NGK replacement cap discussed at length on this forum and problem solved. Not perfect, but it's much more reliable than original.
After getting home, I did an autopsy on the failed cap. Looks to me like the single strand of wire gets stressed from the heat expansion of the hard white plastic insulator and eventually snaps. MG should re-design this POS component and provide owners with replacements.
 
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