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Discussion Starter · #1 ·
I managed to get out this bolt:
199758


199761


It came from here:
199759


It is Honda Part # 90183-422-000. I've searched high and low for a replacement (the threads were corroded and the head is stripped), but have had no luck. Does anyone know of a source? Also, does anyone know the purpose of it? It doesn't hold anything in and the hole for the bolt doesn't go anywhere...

Thanks!
 

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1983 cx650c
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Fixing things like that can be very gratifying, or frustrating. My master on the 650 was not pumping so I got a cheap one on ebay,, was a set with both hand controls, levers, an extra rebuild kit for master cylinder,,, 3yrs no problem, bled it again this year. I did change brake line to stainless, and rebuilt caliper with new pistons and seals. Really glad I didn't rebuild master as kit cost what whole new cylinder with lever. It pumped instantly, bleeding was a breeze. Good wrenching!
 

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Discussion Starter · #3 ·
I was thinking about just buying a whole replacement kit, but I know a grand total of zero when it comes to proper wrenching. So, this is supposed to be my first lesson...but it may indeed be a lesson in futilism.
 

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1983 cx650c
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Search ebay for cx500 brake master cylinder, both kits and complete units available, other sources have them also, like 4into1, randaaks, babbitts online,,,
 

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If your new to wrenching/brakes buy a new mc. kits cost almost as much as new, and I assume your life is worth at least $50 As they say don't try this at home. stay safe also replace the old rubber line(s)
 

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1983 cx650c
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I totally agree that new unit is best for all but the most advanced mechanics. Trying to get my old one to pump ended up damaging paint, destroying numerous rubber gloves and skin on my hands, caused hours of frustration,,, new cylinder was a joy in comparison, and looks identical to original on 650, not the round type as are fitted on some Honda bikes.
 

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That screw looks like the one that holds the front brake light switch to the master cylinder on my gl650. Definitely the same diameter (4mm). Mine is threaded from top to bottom.
199765
 

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1983 cx650c
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The only difference I encountered with the bargain ebay unit is the depth of the threaded hole for mirror mounting. As it is shorter I installed a thick flat washer on mirror threads to get it to fit tightly in the proper position. No biggie, but I couldn't get the mirror lock nut to move enough to set it properly without the washer.
 

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Discussion Starter · #9 ·
I may have overstated my lack of wrenching skills. I've replaced brakes, rotors, lines, etc on cars before, so I have a decent amount of knowledge on how to do the job. I just got done rebuilding the front caliper, finished the MC rebuild, and bench tested it with success (both kits from Brakecrafters). The only remaining thing is sourcing the bolt...
 

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Discussion Starter · #10 ·
That screw looks like the one that holds the front brake light switch to the master cylinder on my gl650. Definitely the same diameter (4mm). Mine is threaded from top to bottom.
The brake light switch on the '80 CX500 slides through a cylinder on the bottom side of the MC and is only held in by tabs on the top and bottom. But, that screw is a 4mm, just oddly not threaded all the way through...

Hand Finger


199768
 

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Possibly someone changed your screw with wrong part? A fully threaded screw is available at machine shop in many lengths if that is what you require? Btw, sounds like you know what you're doing if you've gotten this far, , :)
 

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Discussion Starter · #12 ·
Possibly someone changed your screw with wrong part? A fully threaded screw is available at machine shop in many lengths if that is what you require? Btw, sounds like you know what you're doing if you've gotten this far, , :)
Thanks!

I was thinking this. I just want to make sure I wasn’t missing anything that I couldn’t see. The threaded hole for the screw goes nowhere. I have no clue why. Maybe it was made for aftermarket options?


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Brainfart! One place I've had great success looking at exploded parts diagrams of Honda bits is babbitts online, even if part is not available it gives numbers and descriptions. Also Honda dealers often have old parts diagrams, not sure about FSM as source of information you need.
 

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'84 CX650E that is evolving into a GL500
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FWIW, I am a fairly experienced home mechanic and have rebuilt master cylinders a few times over the years but the last time the ones on my bikes needed doing I bought new ones simply because it didn't make sense to spend more to put a new kit into an old casting than it would to buy a whole new unit.
 

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@nobadwaves Did you ever end up finding this part? Found a few in Australia, but they don't ship here.

I took apart my master cylinder on my 1980 CB750, and found the same strange screw.

I'm not sure why it's not fully threaded, but the Clymer manual says to remove that in order to replace the switch, so I guess it does hold the switch in there somehow.
 
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