Replacing CDI wire (the SBP spark plug one)

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MysterySandwich

MysterySandwich

New Member
Jun 30, 2012
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California
Hey guys, so I read up on this and heard all I have to do is unscrew the wire from the CDI. I grabbed some tiny wires and kind of tried it, but before I knew it all the rubber had gone away...
How should I go about this...?
(do I have a different CDI and it comes out another way?)

Thanks a bunch ;)
 
Groove

Groove

New Member
Nov 2, 2012
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Lexington, KY
Yeah, that link will steer you in the right direction. Your wire was super glued into the CDI unfortunately. You just need to remove all the rubber so the screw is exposed. Kind of tedious but worth the trouble. That SBP replacement you bought works great.
 
2door

2door

Moderator
Staff member
Sep 15, 2008
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Littleton, Colorado
Be very careful when digging that wire out of the CDI. Inside the hollow cylinder where the wire goes is a threaded post. Looks like a sheet metal screw that is actually the high voltage contact. Do not damage or loosen that metal part. If you break it or loosen it you'll need to order a new CDI.
Your new wire should be threaded onto that post with the threads protuding into the core (conductor) of the wire.

Tom
 

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MysterySandwich

MysterySandwich

New Member
Jun 30, 2012
196
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California
Well I got in on, as messy as it was...
So after I cleared up all the rubber (I had to get rid of the hollow cylinder too...) I was supposed to just put the tip of that metal screw into where the wire was on the plug and just tighten it in?

I did just that and I tried riding... it wouldn't start (same problem that made me think I had to replace the spark plug)

I also had a fuel leak (AGAIN!) but it should have still started correct?

-- frustrating, keep throwing money at this thing...
 
2door

2door

Moderator
Staff member
Sep 15, 2008
16,302
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Littleton, Colorado
How are you checking for ignition (spark)?

Remove the spark plug and reconnect the plug wire then lay the plug against the cooling fins of the cylinder head so the place where the wrench goes is firmly against the fins. Now with the clutch engaged (handlebar lever unsqueezed) spin the rear wheel. It makes it easier if you can suspend the rear wheel off the floor and pedal at a good pace.
You should see a spark jumpung from the plug electrodes. That's the little 'L' shaped part at the end of the plug and the small protruding pin at the center.

Got spark?

Oh, and a piece of heat shrink tubing will help at the CDI where you broke off the plastic that surrounds the wire. Did that new wire have a metallic core (conductor) or something that looked like black thread?

Tom
 
Groove

Groove

New Member
Nov 2, 2012
245
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Lexington, KY
Got spark? LOL

Both of mine are already mounted and can't remember what the inside looked like. But the web site says they have an EMI designed alloy core with a heavy duty silicone boot.

They do work great, but I've also not had any trouble with my first bike which I installed an automotive wire and boot from an auto parts store - which did not have a metallic core.. I bought that before reading the advice on this forum...
 
zombie68

zombie68

Member
Mar 17, 2010
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Boise,ID
Would it be possible to avoid "digging" around in the CDI box by splicing a new wire to a short length of the original wire coming out of the CDI?
 
BarelyAWake

BarelyAWake

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Jul 21, 2009
7,194
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Maine
"Not a good idea" isn't particularly helpful w/o the reasoning - which is fairly straightforward given the voltages involved (10,000-25,000v low average automotive), which means any significant resistance resulting from a splice (poor contact/soldering) or even the smallest break in the insulation (including chafe/UV/heat/chemical degradation/cracking) will result in ignition failure & arcing (short to ground).

You can splice copper core plug wires if you're extremely careful to do a proper in-line splice & massively insulate... but in all honesty it's not worth the effort/chance at failure at all as any automotive copper core plug wire is a perfect replacement & comes in all lengths, grabbing one out of a junk car is a viable free solution, checking for weathered/cracked insulation ofc ;)
 
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