Sparkplug cap very loose

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thatguyjay

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Nov 27, 2012
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Hey guys, still working on my first kit and if this has been answered before, I didn't see it in the search I did.

but the problem is...

I have the CDI installed and the spark plug installed (the nipple is gone, so the end of the spark plug is threaded, per the instructions)

The cap from the CDI just sits on the top of it, it doesn't latch on at all. I tried screwing the spark plug into the cap but there's nothing in there but a spot of metal at the top of the cap where the wire connects. The cap is solid plastic, no rubber.

What's going on here? This can't be right, is it? Did I just find (another) broken part in my kit?

Any help or advice is appreciated.
 
crassius

crassius

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Sep 30, 2012
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Yep, your cap is broken. I've had good luck finding nice, NGK caps at the local Honda shop in the right size & shape for about $5.

If you're in a hurry, you can always strip back the plug wire to wrap the inner strand around the top of the plug and hold it with a nut - works well if you don't touch it while it's running.
 
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thatguyjay

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Nov 27, 2012
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So, an update and more clues.

I saw a lot of people recommend replacing the spark-plug wire anyway, but it seems my CDI box is sealed. It looks like they poured epoxy into the little black plastic box and the only screws on it are the ones for mounting. Not at all sure how I would get an NGK cap on as a replacement to the one that's on there, as it's plastic molded to the wire.

NOW if I can get this one to work that would be great. I found this brass fitting inside the bag that had the CDI, is this part of the puzzle? I tried to put it into the cap but it didn't seem to fit right.
 

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MotorBicycleRacing

MotorBicycleRacing

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thatguyjay said:
So, an update and more clues.

I saw a lot of people recommend replacing the spark-plug wire anyway, but it seems my CDI box is sealed. It looks like they poured epoxy into the little black plastic box and the only screws on it are the ones for mounting. Not at all sure how I would get an NGK cap on as a replacement to the one that's on there, as it's plastic molded to the wire.

NOW if I can get this one to work that would be great. I found this brass fitting inside the bag that had the CDI, is this part of the puzzle? I tried to put it into the cap but it didn't seem to fit right.
Click to expand...
That brass fitting is what I was talking about.

To change the wire simply unscrew it from the CDI box and you will
find a sheet metal screw that holds it in place.
 
2door

2door

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Sep 15, 2008
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The spark plug lead on most new CDIs is glued into the wire post. You can dig it out with a small sharp tool and the wire will unscrew out of the CDI. While digging in there be very careful and don't break the threaded metal contact in the bottom of the wire receptical. It will look like the threads of a small sheetmetal or wood screw.
Just carefully dig around the edges of the wire until you can unscrew it.

A new wire can then be threaded back into the hole but make sure that metal part is screwing into the core (conductor) of the replacement wire.
You might not find metallic core wire at your local auto parts store. Most of what's available today is resistance wire and there will be no solid metal core but instead you'll find what looks like a black thread in the center of the wire.

I always suggest to throw the plug boot that comes in the kit in the trash. They are a constant source of trouble. If you replace it with a good automotive quality boot the new boot will require a spark plug with a cap on the top where your current plug just has a threaded part. Replace the plug too with a better one. The kit plugs can give you problems. NGK-B6 is one of the most commonly used plugs for the Chinese 2 stroke engine.

Tom
 
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thatguyjay

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Nov 27, 2012
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There really doesn't seem to be any way to do what you're talking about. On my CDI it's a black plastic box and on the side where the wires come out it looks like the whole thing was flooded with epoxy. If I was to try to try to get at anything I'd basically have to break it apart.
 
2door

2door

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thatguyjay said:
There really doesn't seem to be any way to do what you're talking about. On my CDI it's a black plastic box and on the side where the wires come out it looks like the whole thing was flooded with epoxy. If I was to try to try to get at anything I'd basically have to break it apart.
Click to expand...
The wire exits the box at a molded section which protrudes up through the epoxy. The factory might have gotten a little carried away when the filled the box but I assure you the wire screws into a hollow plastic tube-like area. Check closely where the wire meets the epoxy. I think you'll find what I'm talking about.

If by some chance you have a new or otherwise uncommon CDI, unlike those we all know of, then you might have a problem replacing the wire. A closeup photo would help.

I'll post a photo for you soon.

Tom
 
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thatguyjay

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Nov 27, 2012
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Ah yea I started going to town on it and the wire came off, with a screw as the post. A little chewed up now but no worse for the ware. I really thought you were describing going into the box. I'm about to head over to the auto parts store to see if they have a single spark plug cable that will attach this way. I will update when I return!
 
2door

2door

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For the benefit of others who might have a similar situation here's a couple of photos that shows the threaded contact inside the CDI wire post. The orange wire is a silicone type wire that I use and it contrasts with the black plastic to show where the plastic part protrudes from the epoxy filler.

Tom
 

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SubieGuy

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Sep 3, 2012
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Thanks for posting that pic! ^

I'm just about done my build (w/jackshaft kit) and this is one of the last things I've got to do!
 
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thatguyjay

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Nov 27, 2012
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Yep, that pic pretty much says it.

Now, I tried looking for an NGK B6 but that doesn't seem to be the whole part number when the guy looked it up on the computer so I did a search in the forums to find it's NGK B6HS and that the 5 and 7 will work too.

Regarding the spark plug wire, the one from the store is the same on both ends, with a cap. So I just cut one end off and screw it into the CDI box? Don't want to do it wrong cause the lead wire cost $4.99
 
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SubieGuy

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Sep 3, 2012
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thatguyjay said:
Yep, that pic pretty much says it.

Now, I tried looking for an NGK B6 but that doesn't seem to be the whole part number when the guy looked it up on the computer so I did a search in the forums to find it's NGK B6HS and that the 5 and 7 will work too.

Regarding the spark plug wire, the one from the store is the same on both ends, with a cap. So I just cut one end off and screw it into the CDI box? Don't want to do it wrong cause the lead wire cost $4.99
Click to expand...
Yes you just screw in one end and cap the other!
 
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thatguyjay

New Member
Nov 27, 2012
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Update, I cut the end off of the spark plug lead I got from the auto parts store and it doesn't look like there are any wires in it at all. There is insulation layers and then in the inner-most is like white hairs. What the heck? IS this right?
 
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SubieGuy

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Sep 3, 2012
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Like this??

Someone correct me if I'm wrong, but there's different types of spark plug wire : carbon core and solid core. The one we are looking for is solid core.

The one you got, Jay, may be a carbon core wire?
 

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2door

2door

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thatguyjay said:
Update, I cut the end off of the spark plug lead I got from the auto parts store and it doesn't look like there are any wires in it at all. There is insulation layers and then in the inner-most is like white hairs. What the heck? IS this right?
Click to expand...
As I explained in an earlier post, wire that most auto parts stores carry today is resistance wire. It has no metal conductor at the core but what amounts to carbon impregnated thread. That's what you see at the center of the wire you bought.

Resistance wire was introduced to eliminate RF (Radio Frequency) interference with electronics such as radios and solid state computers in today's cars. It can be used on our little 2 stroke engines as long as you're careful and get the core centered on the threaded contact in the CDI before you screw it in.
I prefer a wire with a copper conductor core but others will tell you the resistance wire works fine. I don't use it.

Sorry about the spark plug designation; yes the full part number would be a B6-HS. The 6 designates the heat range of the plug. The higher that number the colder the plug determined by how deep into the combustion chamber it reaches. The 5,6 and 7 plugs have all been used successfully in the Chinese 2 stroke engines. The 6 is a middle of the road heat range that seems to be the most commonly used.

Tom
 
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thatguyjay

New Member
Nov 27, 2012
31
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Sacramento
SubieGuy said:
Like this??

Someone correct me if I'm wrong, but there's different types of spark plug wire : carbon core and solid core. The one we are looking for is solid core.

The one you got, Jay, may be a carbon core wire?
Click to expand...
Yep it's just like that picture! So, there is no metal in this cable hu? I installed everything and tried to get the engine to start but it's a no-go.

is there a way to confirm the plugg is getting spark?

You guys have been great to stick with me and answer all these questions.
 
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nightcruiser

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Mar 25, 2011
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thatguyjay said:
Yep, that pic pretty much says it.

Now, I tried looking for an NGK B6 but that doesn't seem to be the whole part number when the guy looked it up on the computer so I did a search in the forums to find it's NGK B6HS and that the 5 and 7 will work too.
Click to expand...

NGK BP6HS is a spark plug that works good, but is not always found on the shelf at a local store. The E3.10 also works well, most hardware stores, Home Depot and the like sell this plug in their lawn mower repair section...
 
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