Hi everyone, I'm new here but have had my 1998 FZS600 for around 5 years now. It's a lovely bike and I want to keep it running for as long as possible!
So I've got a misfire and noticed arcing from the spark plug caps/ boots. I swapped the spark plugs out a couple of years ago for NGK CR8E ones. I want to get new spark plug caps but I'm having a hard time deciding what ones I need and there's very little information on the Internet regarding them. I've seen very few sources mention getting NGK SD05F-R 8238. However looking at these, they don't look anything like the original ones on the Fazer. A different shape! Surely these will put unnecessary tension on the leads due to not having the correct angle at the top? One video I watched showed the guy putting these on and it looked like they were too short for the leads! Also I don't like the red look, so I looked up some more and found NGK SD05F 8022. I'm assuming these are the same caps as the red ones but in black?
Which leads me to my next issue .. the spark plugs I have (NGK CR8E) have a resistor in them and these NGK spark plug caps also have a resistor in them... Will this not be overkill and dampen the spark? From my understanding sometimes doubling the resistors can actually be more harmful than good. Is this the case with the fazer?
Just hoping for some advice and opinions. Thanks!
23-10-25, 06:48 AM
(This post was last modified: 23-10-25, 07:09 AM by Gnasher.)
Take a look HERE use the info
THESE should do the job but drop them a line to confirm, they're very helpful chaps and will point you in the right direction. OE version are approximately £60 odd each!
Double resistors shouldn't make any difference l. But if your concerned just get non resistor plugs.
Later
(23-10-25, 12:11 AM)Fazered Wrote: Anyone? Apologies, looks like Gnasher go to it.
(23-10-25, 10:48 AM)b1k3rdude Wrote: (23-10-25, 12:11 AM)Fazered Wrote: Anyone? Apologies, looks like Gnasher go to it.
That’s exactly what I replaced my OEM plug caps with and went from a serious misfire in dampish conditions, to riding 500 miles in an absolute frog strangler, without missing a beat.
23-10-25, 09:56 PM
(23-10-25, 03:13 PM)AndyKirby Wrote: "absolute frog strangler" I don't know why I found this funny, but I laughed for a good 15 seconds... 
24-10-25, 09:24 AM
(This post was last modified: 24-10-25, 10:48 AM by Fazered.)
(23-10-25, 06:48 AM)Gnasher Wrote: Take a look HERE use the info
THESE should do the job but drop them a line to confirm, they're very helpful chaps and will point you in the right direction. OE version are approximately £60 odd each!
Double resistors shouldn't make any difference l. But if your concerned just get non resistor plugs.
Thanks so much pal! They look more suitable!!
(23-10-25, 10:48 AM)b1k3rdude Wrote: (23-10-25, 12:11 AM)Fazered Wrote: Anyone? Apologies, looks like Gnasher go to it.
No need to apologize! Was just wondering if the forums were active or not. Seems like they are! I'll be sticking around. Thanks guys!
Update: so after contacting yambits they told me NGK don't make plug caps suitable ? as Fazer plug caps are extra long. Did you folks have any issues with the coils reaching these ones above?
Don't make plugs or don't make plug caps?
I have to say I've only ever changed one set plug caps on an FZS600. All the other times the arching was down to cracked plugs or damaged leads. Are you certain the plug caps are at fault here?
Later
(24-10-25, 09:59 AM)Gnasher Wrote: Don't make plugs or don't make plug caps?
I have to say I've only ever changed one set plug caps on an FZS600. All the other times the arching was down to cracked plugs or damaged leads. Are you certain the plug caps are at fault here?
Plug caps*. They said they don't make plugs caps for the FZS600. I'm pretty certain it's due to cracked plug caps as I can see the arcing coming through the caps. I recently replaced the spark plugs and I already have a back up set of leads at hand. Surely if it was the leads or plugs themselves then I wouldn't see arcing from the cap cover?
24-10-25, 11:26 AM
(This post was last modified: 24-10-25, 11:30 AM by Gnasher.)
(24-10-25, 10:47 AM)Fazered Wrote: Surely if it was the leads or plugs themselves then I wouldn't see arcing from the cap cover?
Nope you'd still see it. Assuming there not all arching? Have you tried swapping the plug from one that isn't, into the cylinder that is arching? If with plug from a cylinder that isn't arching in there and it doesn't arch it's not the lead/cap, it was the plug. Than try swapping the cap that is arching into a cylinder that isn't if it's not longer arching, it's the lead or the connection to the cap. That latter is a well known fault. If it's still arching it's the cap.
FZSs are getting long in the tooth now so it's not surprising things are getting hard to find.
All you need do is measure the length of the current cap and look HERE for a very close match you need plug size 10/12mm and 5kohm. Get the code and find a cap try HERE and HERE for starters they're are many more you've just go to look. It doesn't matter what bike just that the specs match. You may have to go for straight and they'll be pushed further into the head, which will probably mean you'll need longer HT leads and careful use of covered jaw pliers to remove them.
Later
24-10-25, 11:36 AM
(This post was last modified: 24-10-25, 11:41 AM by Fazered.)
(24-10-25, 11:26 AM)Gnasher Wrote: (24-10-25, 10:47 AM)Fazered Wrote: Surely if it was the leads or plugs themselves then I wouldn't see arcing from the cap cover?
Nope you'd still see it. Assuming there not all arching? Have you tried swapping the plug from one that isn't, into the cylinder that is arching? If with plug from a cylinder that isn't arching in there and it doesn't arch it's not the lead/cap, it was the plug. Than try swapping the cap that is arching into a cylinder that isn't if it's not longer arching, it's the lead or the connection to the cap. That latter is a well known fault. If it's still arching it's the cap.
FZSs are getting long in the tooth now so it's not surprising things are getting hard to find.
All you need do is measure the length of the current cap and look HERE for a very close match you need plug size 10/12mm and 5kohm. Get the code and find a cap try HERE and HERE for starters they're are many more you've just go to look. It doesn't matter what bike just that the specs match. You may have to go for straight and they'll be pushed further into the head, which will probably mean you'll need longer HT leads and careful use of covered jaw pliers to remove them.
I'll give that a try mate, thanks so much for taking the time to help me! Really appreciate the info!
Absolute legend Gnasher! Saving me money too by linking those sites also. eBay prices are ridiculous!
25-10-25, 06:55 PM
(This post was last modified: 25-10-25, 06:55 PM by Fazered.)
Went out to the garage today to check the bike. It ran without any arcing for about twenty mins although my revs are fluctuating up and down still. Then I heard the clicking and looked down to see that over a short period of time all 4 plugs are arcing. It seems to be low down on the plug cap where the plastic meets the rubber. Can't do the test.of swapping caps over as all 4 were arcing. Any more ideas or tips?
I have SD10F (10Kohm) fitted to my sons bike and they work perfectly, even with 10mm cut off the ends of the coil wires.. These match the resistance of the original plug caps.
The standard resistance in the coil and plug circuits is 15kohms and this is what it is designed to use. Caps 10Kohm and Plugs 5Kohm.
The more common are the SD05F (5Kohm) and work well also.
The original caps are still on my own bike but are fitted with NGK 10Kohm resistors (removed from a set of SD10f caps) and used the NGK top and bottom boots as they were tighter on the cap. I just prefer the look of the original caps as the bike is almost totally standard looking.
They are a better quality resistor as they are wire wound with stainless ends compared to the originals which are Carbon resistors. These carbon resistors breakdown and/or crack and breakdown sending the resistance into megohms. This is the cause of the misfiring and arcing, now add water ingress and you have a recipe for disaster as this corrodes the worlds smallest internal shim and internal spring.
Fitting the NGK resistors allowed me to do away with the shim which was broken in two caps and badly corroded in the other two caps, but I was able to clean up the corrosion on the spring and the internal corrosion at the brass flat top end of the cap. The inners of the original caps can be removed by undoing the internal screw with a wide flat screwdriver and everything should fall out. If the spring sticks, a phase tester size screwdriver will dislodge it.
I was told recently by the NGK distributer in Ireland that NGK will no longer be making Plug caps, as there is little or no demand for them due to the the prevalence of Coil on Plug set-ups.
(25-10-25, 09:22 PM)unfazed Wrote: I have SD10F (10Kohm) fitted to my sons bike and they work perfectly, even with 10mm cut off the ends of the coil wires.. These match the resistance of the original plug caps.
The standard resistance in the coil and plug circuits is 15kohms and this is what it is designed to use. Caps 10Kohm and Plugs 5Kohm.
The more common are the SD05F (5Kohm) and work well also.
The original caps are still on my own bike but are fitted with NGK 10Kohm resistors (removed from a set of SD10f caps) and used the NGK top and bottom boots as they were tighter on the cap. I just prefer the look of the original caps as the bike is almost totally standard looking.
They are a better quality resistor as they are wire wound with stainless ends compared to the originals which are Carbon resistors. These carbon resistors breakdown and/or crack and breakdown sending the resistance into megohms. This is the cause of the misfiring and arcing, now add water ingress and you have a recipe for disaster as this corrodes the worlds smallest internal shim and internal spring.
Fitting the NGK resistors allowed me to do away with the shim which was broken in two caps and badly corroded in the other two caps, but I was able to clean up the corrosion on the spring and the internal corrosion at the brass flat top end of the cap. The inners of the original caps can be removed by undoing the internal screw with a wide flat screwdriver and everything should fall out. If the spring sticks, a phase tester size screwdriver will dislodge it.
I was told recently by the NGK distributer in Ireland that NGK will no longer be making Plug caps, as there is little or no demand for them due to the the prevalence of Coil on Plug set-ups.
Very interesting! Electrics aren't my strong point (if you can't tell ?), so I appreciate the extra info! I wonder if water ingress could be an issue here for me then! The garage does get slightly damp inside ? Looks like I'll take it all off and investigate at some point in the next week or so when I have some time. I just want it back to running how it was as it's such a nice bike! Plan on doing some routine maintenance early next year but there's no point in me doing that until I get the engine running good again lol
(25-10-25, 09:53 PM)Fazered Wrote: I wonder if water ingress could be an issue here for me then!
Try squirting in some WD40 and see if that helps sort it out.
(25-10-25, 09:53 PM)Fazered Wrote: Very interesting! Electrics aren't my strong point (if you can't tell ?), so I appreciate the extra info! I wonder if water ingress could be an issue here for me then! The garage does get slightly damp inside ? Looks like I'll take it all off and investigate at some point in the next week or so when I have some time. I just want it back to running how it was as it's such a nice bike! Plan on doing some routine maintenance early next year but there's no point in me doing that until I get the engine running good again lol
Not necessarly while in the garage, but while riding in the rain and/or washing it. When water gets in it causes the corrosion and that leads to problems.
WD40 will push the water out, but will not fix bad corrosion.
You best bet but 4 SD10F caps cut 10mm off the leads and fit the caps. That should sort the arcing problem.
https://www.fc-moto.de/en/NGK-Spark-Plug-Cap-SD10F
26-10-25, 03:43 PM
(This post was last modified: 26-10-25, 03:47 PM by Fazered.)
(26-10-25, 12:50 AM)unfazed Wrote: (25-10-25, 09:53 PM)Fazered Wrote: Very interesting! Electrics aren't my strong point (if you can't tell ?), so I appreciate the extra info! I wonder if water ingress could be an issue here for me then! The garage does get slightly damp inside ? Looks like I'll take it all off and investigate at some point in the next week or so when I have some time. I just want it back to running how it was as it's such a nice bike! Plan on doing some routine maintenance early next year but there's no point in me doing that until I get the engine running good again lol
Not necessarly while in the garage, but while riding in the rain and/or washing it. When water gets in it causes the corrosion and that leads to problems.
WD40 will push the water out, but will not fix bad corrosion.
You best bet but 4 SD10F caps cut 10mm off the leads and fit the caps. That should sort the arcing problem.
https://www.fc-moto.de/en/NGK-Spark-Plug-Cap-SD10F
Ahh! That explains it then! And I never even considered that those other ones aren't the same rating (5Kohm) as the originals (10Kohm) So looks like I'll buy the ones you said as that makes more sense! Might even copy your idea and use the OEM cap and just put the internals and rubbers into it from the new ones haha. Thanks so much! I'll update when I get round to doing it. Just to confirm you use CR8E plugs?
(25-10-25, 09:22 PM)unfazed Wrote: The original caps are still on my own bike but are fitted with NGK 10Kohm resistors (removed from a set of SD10f caps) and used the NGK top and bottom boots as they were tighter on the cap. I just prefer the look of the original caps as the bike is almost totally standard looking.
Pictures would be good?
Later
(26-10-25, 05:39 PM)Gnasher Wrote: (25-10-25, 09:22 PM)unfazed Wrote: The original caps are still on my own bike but are fitted with NGK 10Kohm resistors (removed from a set of SD10f caps) and used the NGK top and bottom boots as they were tighter on the cap. I just prefer the look of the original caps as the bike is almost totally standard looking.
Pictures would be good?
Pictures of what?
(26-10-25, 05:54 PM)unfazed Wrote: (26-10-25, 05:39 PM)Gnasher Wrote: (25-10-25, 09:22 PM)unfazed Wrote: The original caps are still on my own bike but are fitted with NGK 10Kohm resistors (removed from a set of SD10f caps) and used the NGK top and bottom boots as they were tighter on the cap. I just prefer the look of the original caps as the bike is almost totally standard looking.
Pictures would be good?
Pictures of what?
You're modified standard plug caps if course.
Later
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