79-80 RH Kill/Start Switch Replace/Repair Options


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divan
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79-80 RH Kill/Start Switch Replace/Repair Options

Post by divan »

Hi, all.
I've been doing some refurbishing and mods to the wiring and electrics on my '79, and thought I'd pass along some research I've done on options for repairs/replacements for the right handlebar switch. As we know, the original switch unit and harness are no longer available from Honda, and can be pretty hard to find as OEM parts, except used units at high prices. Most of us know that Phil ("FalldownPhil" on the forum) offers a reproduction unit, as do Z1 Enterprises. It's possible there are other reproduction sources I don't know about. This is a good solution to a bad switch, if you aren't interested in OEM. I believe Phil's prices are a bit lower than Z1, and it's always good to support a fellow CBX club member.

If you're interested in an keeping OEM, or are just wanting to do some repairs to your switch without replacing it completely, you may be interested in the bit of research I'm reporting on here. Curious about options for working on these switches, I did a bit of rummaging around through Honda parts lists and came across an interesting "discovery" (possibly already known to some folks). When the early 79/80 bikes were made, it looks like the switch units themselves were sourced along with several other bikes, and in all of these bikes the glass-filled PBT plastic housing units and switches are identical, though the harnesses are a bit shorter and employ the smaller 2.8mm/0.110" male Sumitomo terminal pins in a red 9 pin connector. Switches from other Honda bikes will work, more or less; but the only ones I've found that are exact housing/switch matches for the US spec 79/80 CBX are limited to the US spec 79-82 Honda CB 650 A/C, DOHC CB750 F/K/L, and the 80-82 CB900 C/F. Earlier SOHC 750's and the DOHC 750SC "Nighthawk", do not match. In other words, only these bikes that shared production runs with CBX are. Disclaimer: I have no hands-on experience with CBX's other than my US '79, though I'm reasonably sure this info applies to the US '80 (part numbers match); not at all sure about later CBX's (part numbers don't match).

If you look through the Honda parts lists on these bikes, you will see 3 different part numbers: the function/component # is the same -- 35130; the product and classification #'s vary -- 425-672; 461-770; and 463-505. The 35130-463-505 is the one with the housing that matches the CBX. The other two were for different series of the CB650, and are no longer available from Honda as new parts. At some point Honda substituted the 505 part (US Spec) for the other two, and now it's the only one you can get new.

You can also find these CB switches both used and aftermarket on E-Bay and from other sources. The CB 750's and to a lesser extent the 650 series and 900 series are very popular "retro" restoration bikes right now, so quite a few sources for the parts are out there. If buying used, just be careful to check the part number (if available) or closely examine the photos to be sure you're getting the "505" part. Many of the used 650/750/900 parts I've looked at on E-Bay are not the "505". Most likely they come from the other series, with front/forward loaded cables, light switches (that's what the unused "H-P-Dot" markings on the front of the housing are for), and so on. Prices used range around $30-$50; new from Honda, if you look around a bit, around $100.

Both the CB and CBX units from these years (and others) were all manufactured for Honda by M-Tec and have the Tec logo on the bottoms of the unit. Out of curiosity and to be sure of the match, I bought a used '82 unit on E-Bay for $30 and made the comparison with my original switch (see photos below). Throttle mounts, cable routing and channels, switches, exterior markings all match. The switches when disassembled are also identical internally. The only difference is in the wire harness. The 9 wires & wiring codes (colors) are the same. But the harnesses on the non-CBX parts are approximately 3" shorter than on the CBX, and the wires terminate in the smaller 2.8mm connector and terminals. To use the unit on a CBX you can just barely stretch the fit into the headlight housing, but it's pretty tight -- probably not a good idea. Some mods would be necessary to use the whole part and harness, but it can be done. The terminal pins, for example, are easily replaced with the 0.250" pins used in the X, along with a 0.250 white connector. The shorter harness options would be to splice & shrink-tube small (3-4") lengths of wire to stretch the harness or -- if you're very good at soldering or know of a professional who can do it -- replace the wires at the solder points.

If all you need is to replace parts on your switch, these are all interchangeable -- internal contacts, springs, the starter push button/spring, or the kill switch handle, or the lower housing (where the throttle cables attach, the upper housing, etc.

So if you're wanting an OEM switch unit rather than aftermarket, for restoration or if you need to repair something in the unit, and are able or willing to do some wire work, you might want to consider one of these CB units The units are fairly easy to disassemble and all of the parts can simply be swapped out. Here's some examples: Lower housing cracked or threads stripped on throttle cables joints -- this housing disassembles from all of the wiring points and can simply be swapped with the replacement part, complete with the "Tec" logo. Kill switch handle broken or contact/spring at handle worn or corroded -- simple swap out. On the Kill switch, the lower contacts can also be swapped if you're willing or able to do soldering (this is tricky if you don't know how to solder properly, so be careful). An alternative would be to splice new wire of short lengths (3-4") between the two harness cables (black/black-white) and the new switch cables. I'd suggest open barrel splices, not closed barrel -- too bulky. Open barrels are smaller, easier to crimp, and tend to make better electrical/mechanical connections. Stagger the splices to reduce bulk in the sleeve, insulate with good adhesive shrink tube.

The start/headlight switch contacts are a little more difficult to disassemble, but it can be done if you're careful. Once disassembled, the top contacts/spring and push button/spring are easy to remove/replace; bottom contacts can be swapped as a unit. Soldering new wires here would be extremely difficult because of close spacing of the 4 wires -- only try this if you are very skilled at soldering. But again, splices, carefully spaced along the harness to prevent bulk, would work. The top plastic housing can be similarly replaced, if yours is cracked, broken, or badly worn (if appearance is important to you). It's a little more work because both of the switches and all of the wiring lives here, but it can be done. And so on.
If you don't have the time or desire to tinker a bit, and don't care about OEM, the aftermarket CBX switch/harness is the answer. Again, old hands will probably already know about this, but a lot of us who wrench on an amateur basis may find this info useful -- I hope so.


'82 CB650.JPG
'79 CBX.JPG
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Dick Sullivan

steve murdoch icoa #5322
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Re: 79-80 RH Kill/Start Switch Replace/Repair Options

Post by steve murdoch icoa #5322 »

Heck of a first post, Divan.
Thanks for sharing your in-depth research.

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Re: 79-80 RH Kill/Start Switch Replace/Repair Options

Post by EMS »

A variety of other switches indeed work and are similar to the CBX units. Most of them have very slight differences not immediately obvious. In most cases the red color and the exact shape of the "kill switch" knob differs. Functionally, they are the same.

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FalldownPhil
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Re: 79-80 RH Kill/Start Switch Replace/Repair Options

Post by FalldownPhil »

Great article, thank you !!
Phil
When you are up to your ass in alligators it is sometimes difficult
to remember that your objective was to drain the swamp !!

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NobleHops
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Re: 79-80 RH Kill/Start Switch Replace/Repair Options

Post by NobleHops »

Outstanding contribution!
Nils Menten
Tucson, Arizona, USA '80 CBX, sort-of restored :-)

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