RestoCycle How-to: Disassemble and Service a Honda CBX ignition Switch Base

[NobleHops]

This one may have been covered before.

Resistance and voltage drop that goes along with it are the ENEMY of our old bikes' wiring harnesses. This causes dim lights and weak spark, overtaxes the charging system and eventually starts melting stuff. Must fix! We spend a LOT of time during our restoration and deep service projects making the wiring perfect, and that includes going inside the contact base of the ignition switch.

Alrighty, here's our patient. This 40-year old ignition switch lived in one of our Honda CBX projects, but as usual it's gone a little rotten, and it's critical that it be completely serviced as ALL of the motorcycle's electrical current passes through here (if you're not employing relay modifications). This is actually TWO different mechanisms - the mechanical key/lock assembly is the metal part, and the electrical "business end" is actually contained at the very bottom, and within that black plastic part to the left. We're going in.

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Way in the back of the 81-82 Prolink CBX manual is where you'll find the best description of how to get in here, but most Hondas of the era will work similarly. The proper position of the key may vary - what's important is to verify that the recesses in the white rotating contactor be aligned with the plastic fangs of the contact base arms before you attempt to remove it. This will make sense in a moment

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Step 1 is to insert the key and turn it to the position that aligns the fangs with the recesses in the rotating contactor piece. On this '79 CBX it was as shown, between "ON" and "P". That will align the retaining lugs (we call them "fangs") with a slot in the white plastic rotating part of the contact base so it can be extracted without damage.

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With the key in ACC you can now depress the two lugs so the contact base can be extracted. BE GENTLE! and stay as far away from the edge of the fang where it engages with the slot in the metal as you can. If you are ham-handed about this you will round over the fang and then it will not want to engage, and that will lead to secondary problems when you reinstall this. You may go ahead and ask us how we learned this. You want to leave the edge of that fang sharp and intact. If you DO mess this up and it will not engage positively, there are Emgo replacement bases, but we have never liked the way those fit, and the plastic is a lot softer.

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With the fang depressed on both sides, you can now extract the contactor base. Your third hand will come in handy here

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Wiggle it carefully out.

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[NobleHops]

Now you can see how these two mate up. The lock section has an actuator that protrudes from the mechanism and engages its mate in the contactor base. And those have to be in proper alignment on reassembly of course. Liquid lube sprayed into the lock WILL eventually make its way out and into the contactor base, and that is yet another good reason NOT to use liquid lubricants in these mechanisms. Clean out this area while we're here, and maybe apply a little graphite to the key when we're finished to properly lube the lock.

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Here's the contactor base separated from the lock. Look closely at this and you'll see why it has to be in a certain position. See the two black arms with the fangs left and right? Now look at the white plastic behind it - see the two recesses behind the arms with that white plastic piece rotated into this position? If it's not rotated properly into this position then the arms have nowhere to go when you depress them, and the fangs get damaged.

We're almost "there". Flip it over, separate the two black arms a skosh and you can lift the black cover off.

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These spades are what engages with the harness connector. These need to be clean and free of all the oxidation that has accumulated over 40 years. Same with the connector side.

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With the cover off, now separate the two halves of the contactor base, CAREFULLY. There is stuff that can and will go SPROING, and you want a look at it before it does. You'd really be better off inverting this with the white side down and pry/lifting the black base off.

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Ya, well, I didn't do that and so it all went SPROING. Those two 'L"-shaped lugs insert into the slots next to the springs. Stretch those springs out 1/4" and make those lugs SPOTLESS before you reassemble. Clean and bright.

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This is the other half of what you pulled apart. Those copper terminals are what the raised dots on the lugs make contact with. It's not such a stretch to see where our resistance and voltage drop was coming from, eh? Clean those same as the other lugs, clean and bright.

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[NobleHops]

These actually had a trip through the ultrasonic, and we followed with some careful hand cleaning of the copper contact points and a spray with Deoxit. This is easily done by hand, you don't strictly need the ultrasonic. Clean and good to go.

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A very light smear of silicone dielectric grease will protect these contact surfaces from oxidation and slightly waterproof them too. A little is enough.

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Reassemble the contactor base, align the slot to mesh up with the switch, verify the key position is still correct to accept insertion of the base - you can see that the three black plastic arms are aligned with the recesses in the white plastic piece. Slide it back into the switch, making sure the two fangs positively engage with the metal of the switch. NOTE. This recess in the center that mates with the switch body is slightly tapered, and so is the actuator from the main switch body. Match that up.

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Presto, switch is now electrically as perfect as we can make it, and no longer a source of resistance and voltage drop in the wiring harness.

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