Topic: 79 CB650 The Mayor - Revive and Freshen Up

[DaveBarbier]

So I’m looking for a shorter clutch cable. This one I have is about 2” too long. I just noticed that it’s looped wide enough to touch the #4 header when I turn the bars right and it’s melting the sheathing. I looked on CMSNL for the part number of the UK model I think it was which came with shorter bars. Found one on eBay and asked the guy to measure it. It’s much too short. My current one is 52.25” long and the eBay seller measured his at 46.5”.

My clutch cable is OEM but I must not have stock bars. They really do look stock though and have the drilled holes for the controls. And looking in the book I have it routed exactly as it’s shown. Not quite sure what’s going on there. I could go through motion pro and have them custom make me one but that’s going to be like $90 including shipping. And the last cb650 motion pro cable I got for my other bike with clipons didn’t have the correct hardware on the engine side, I had to modify it.

Anyone have any info on the length of OEM clutch cables? OR, better yet, anyone with stock 79 650 want to let me know what clutch cable you have?

[onepieceatatime]

I have a handful of cables from cb650s, none from a 79, as far as I am aware, but I can measure them and see if one is shorter when I get home from work in the morning.... If I can remember that long.

[bwaller]

I use a 400F cable on my race bike with clip-ons. I can check the length tomorrow.

[DaveBarbier]

I have a handful of cables from cb650s, none from a 79, as far as I am aware, but I can measure them and see if one is shorter when I get home from work in the morning.... If I can remember that long.

That would be cool, if you get a chance post up some lengths.

By the way I’m measuring the sheathing only.

See the pictures:

[DaveBarbier]

I use a 400F cable on my race bike with clip-ons. I can check the length tomorrow.

Really, that’s interesting. The 400f doesn’t have the same engine side hardware the 650 does. Do you just have it rigged up? I’d rather have the proper hardware. I’m sure the clip on cable length is too short for me though.

[onepieceatatime]

Measuring just the sheath, I have one that is 52, one that is 53.25 and one that is 53.5. I did not measure the 2 that are on bikes. I also measured one from a 81 cm400c that is in a spares bin, it was only 43(ish). I didn't pay much attention since it was so much shorter. I may have one from an early 80s cb900f I can measure, but that will take a little bit of digging through bins.

Sent from my Pixel 4 XL using Tapatalk

[onepieceatatime]

Found it, but that one is 55 inches.

Sent from my Pixel 4 XL using Tapatalk

[DaveBarbier]

Ah thanks, really appreciate the info. I’ll continue my quest!

[DaveBarbier]

Ok so I resolved my clutch cable issue. Did a little research and decided to shorten my existing cable. So much easier than I thought it would be and now it’s routed correctly and functions perfectly without hitting the exhaust.

First I cut the old end of the cable off with a dremel. Then pulled the cable out and heated the crimped ferrule a bit with a torch and it slid right off. Cut the sheathing with the dremel 2” and reinstalled the ferrule. That part took some time. You can’t just push back the ferrule since it was crimped so I pushed it on the ends of progressively larger and larger drill bits until it got big enough to slide on. Then re-crimped it with some wire crimpers. Next I cut the cable itself so it would have the same stick out as the old cable did. Which in my case was about 3 1/4”. I made it a little shorter at 3” accidentally but that was no problem. You have plenty of adjustment when on the bike.

Made a new barrel nipple out of some brass I had because I didn’t like the idea of drilling and reusing the old one. I could have bought one from VenhillUSA for about 30¢ but with the holiday shipping times being so delayed I didn’t want to deal with it. I had the brass and have a lathe and drill press so why not. Parts are so small I had to channel my inner Clickspring.







Made a bird caging tool out of some scrap angle steel.




The small drilled hole has to be a hair smaller than the cable so it will clamp on it when in the vise but not too small where it mushes or pinches the cable.

Clamped the cable in there and gave it a couple light whacks with a punch.







Heated up some 63/37 solid core solder on a camp stove I set up on saw horses because I don’t have a solder pot. Used a brake caliper piston from a 2003 R6.


As that was coming up to temp I had the cable end soaking in acetone. Then dipped just the bird cage in flux (not too far because you don’t want solder going up the cable, it needs to stay flexible) and slid down the barrel nipple and dipped the whole thing in flux again, just barely enough to cover the nipple. Again, not going too far as to get flux on the cable on the other side of the barrel nipple.

Dipped the cable into the molten solder just enough to cover the barrel nipple. Actually dipped it a few times like one does to build up wax when making a candle. I wanted to be sure the hole in the barrel nipple was full.




The results are a perfect cable end. Honestly, I’m very pleased with myself, haha.

[grcamna2]

That's very nice cable building skills there Dave  Did you ever attempt that before ?
That looks nice.I suppose you could have ordered different cables and gotten disappointed plenty with what you received and possibly needed to return,with all this Holidays/Pandemic shipping sh*t.I think you did much better doing your own.How does the cable feel to you now ?

[DaveBarbier]

That's very nice cable building skills there Dave  Did you ever attempt that before ?
That looks nice.I suppose you could have ordered different cables and gotten disappointed plenty with what you received and possibly needed to return,with all this Holidays/Pandemic shipping sh*t.I think you did much better doing your own.How does the cable feel to you now ?

Thanks, I’ve only shortened a choke cable a few years back. Not nearly as much tension. I could have ordered a custom cable from Motion Pro at over $80. So this was a much better option. The cable feels perfect. Smooth and predictable.

[RAFster122s]

It was wise to support the cable while spreading it like you did. Doing it without support makes the cable unwind too much and you end up wicking solder and Acetone higher than you desire because of capillary action when it isn't wound well or like the factory.
Wish I had your skills and tools ...

Very professional looking results.


This reminds me of magnet wire and its difficulty soldering.


Tip for how to on soldering magnet wire that is coated. Take an aspirin and tile or metal plate suspended off your bench. Clamp your magnet wires in some fine locking pliers or forceps you don't mind to de-temper or grasp them in some long needle nose pliers at the tips so you can manipulate them with one hand. Just enough to hold them, you don't want to nick or mangle the wire causing a break later due to vibration.
(Don't forget a glove if using forceps as the heat will travel, or not a bad idea even if using pliers.)
Light your torch and get a good blue tip going. hold your wires(s) to be cleaned of enamel on top of the aspirin and use the torch to melt the aspirin/burn the aspirin dragging the ends of the wire slowly through the aspirin bubbling melting aspirin.
*****DO NOT Breathe the smoke/vapor coming off the process.*****
Maybe have a fan a distance away from you lightly blowing across the work area so fumes go away from you so you do not breathe the fumes. The salicyclic acid compound in the aspirin eats the enamel coating off the wires.
Wikipedia says:
  Aspirin, an acetyl derivative of salicylic acid, is a white, crystalline, weakly acidic substance, with a melting point of 136 °C (277 °F), and a boiling point of 140 °C (284 °F).
Other names: 2-acetoxybenzoic acid; acetylsalicylate; acetylsalicylic acid; o-acetylsa...
License data: EU EMA: by INN; US DailyMed: Acetylsalicylic_acid; US FDA: Aspirin
Pronunciation: acetylsalicylic acid /əˌsiːtəlˌsælɪˈsɪlɪk/

Works nicely, Then you clean the wire ends with Acetone wiping them towards the ends, flux them and solder.

Trying to solder them without cleaning is a mess and high temp magnet wire coating are still cleaned off using this method without damaging the wire. You could sand the coating off but you run the risk of breaking the wire or similar failure later. And usually not the case with our motorcycles but, fine copper magnet wires like used in headphones and speakers are all but impossible to sand without breaking and chemical method like this works like a charm. The red or green almost transparent coating of magnet wire is it's insulation coating. If you ever wind a stator or motor or other device with magnet wire protecting the wire from nicking the coating is important when winding that coil around the metal part. Often the parts will have a powder coated side that radiuses the part that was machined to shape, this helps protect the enamel/magnet wire from nicking when using snug force but not gorilla pull with all your might force. Testing the bare metal of the object being wound with one lead on bare metal (sand small spot clean away from winding or that clean screw threads into as your metal contact for one lead and test the cleaned end of your magnet wire on the other for continuity when you start and as you take short breaks while winding. It you have continuity then you have a break and need to rewind that area and splice in new section or start over.

David M

[DaveBarbier]

This is regarding the o-ring sizes for the fuel rails and accelerator pump rails on the PD carbs for the ‘79 & ‘80 CB650. I posted this last year replying to another thread by someone else but wanted to keep this info here also so it’s all in one place.

In looking around this forum and other forums I either found no answers or the wrong answers. The PD51A carbs on my ‘79 650 were leaking from the fuel joint tubes and accelerator pump joint tubes. No parts fiche lists the o-ring size because they’re part of an assembly that’s NLA. Couldn’t measure the existing o-rings because they were all shriveled and crumbly. Got some Buna-N o-rings from McMaster Carr in a couple close sizes and picked the ones that fit the best.

Fuel rail o-rings: 6mm ID x 2mm cross section
McMaster part number: 9262K166

Accelerator pump rail o-rings: 2.5mm ID x 1.5mm cross section
McMaster part number: 9262K626