what is inside the spark plug cap?

GoldenMotor.com
J

Jim C

Member
Jul 11, 2010
200
6
18
Long Beach Calif
Title asks the question. My new build is about done. I mounted the coil and removed the spark plug and everything in the cap fell out. A small spring and a brass part that fit over the spark plug.
How do I put it back together, what is the order of assembly where does the spring go and there does not appear to be any contact in the cap/
 
bairdco

bairdco

a guy who makes cool bikes
Aug 18, 2009
6,537
264
63
living the dream in southern california
It all goes into the garbage.

The stock plug wire is one of the biggest cause of problems. The best thing to do is go to a good auto parts store, buy a length of 7mm non resistance, copper core wire, a 90° plug boot, and a terminal end, and an NGK B6HS plug. All for under $10.

You can make your own wire in a few minutes with basic tools.

Or you can buy a ready made plug wire, like a coil wire.

The original plug wire unscrew from the CDI unit. Most are epoxied in now, so it'll break off, and you'll have to carefully dig out all the remnants of it with a pick, knife, or very small screwdriver.

Then just cut the end of your new wire flush, and screw it in till it stops. Slipping a piece of heat shrink tubing, big enough to go over the plastic end of the CDI is a good idea.

Repairing your original is a waste of time, will fail sometime soon when you're on the road, and I don't remember how they go back together because I throw them away.
 
2door

2door

Moderator
Staff member
Sep 15, 2008
16,302
175
63
Littleton, Colorado
Ditto: That plastic piece of junk that comes with the kits is without a doubt the weakest link in thes Chinese 2 stroke kits. Throw it away and do what Bairdco suggested.

One thing I'll add is to be very careful digging the original wire from the CDI if yours is glued in. There is a small threaded part protruding from the socket where the wire goes. It threads into the center core of the wire and is a critical electrical contact. Don't break it!

As far as the wire itself, if is is long enough, use it but replace that plastic boot (cap) with a good automotive quality item. The kit wire is at least metallic core compared with most wire you'll get from an auto parts store today. Most of it is resistance wire unless you specifically ask for metallic core wire. Copper is the best. Many parts stores today don't carry it. Motorcycle shops, lawnmower or small engine repair shops are a good bet if you have trouble finding it.

Tom
 
J

Jim C

Member
Jul 11, 2010
200
6
18
Long Beach Calif
Thank you guys. The last time and only time I tried to remove the wire from a CDI unit I destroyed the CDI and had to buy a new one. I am not opposed to that if I have to. I just wanted to know if I could fix the one that fell apart. A spring and a brass part fell out on to the floor. I think the spring goes in first followed by the brass and it screws into the cap. If if put it together, ground the plug and rotate the motor I can't see any spark. Thanks again for your help and I do know the wire is junk.
 
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