Topic: Resurrection of A 1972 CB500 Four - Horribly Varnished Carbs

[b52bombardier1]

Hello,

   This is the beginning of what will likely be a long string of posts but I have run up against a filthy set of four carbs.  As usual, the carbs were not drained when the bike last ran way back in the 70's.  The tank is in equally bad shape but might be salvageable.

  I have the carbs removed by all except by the throttle cables.  Reading the shop manuals - Honda and Clymer - it appears they want me to disassemble the link bar to detach the carb set from the cables.  Why can't I simply back the cable adjusters loose and detach the carbs at the swaged things at the far end of the two cables?

  The float bowls are badly varnished up.  I will not be able to get the #1 carb main jet out without destroying it.  And the brass float pin for carb #1 is seized in tightly such that it will not come out. Any suggestions for removing the brass pin without breaking the post?  I have not even looked in the bowls for the other three carbs but they are probably as bad.

  The throttle slides for carb #3 and #4 are also stuck in the carb body - no movement at all by throttle cable. And Brake Kleen is not doing much.

  So . . . can I detach the set of four carbs at the swaged cable end?

  How do I unstick the slides without damaging them?

 And how do I remove the brass float pins without damage?  My other Honda bikes all have pins of this type but I have never seen one stuck this badly.

   I may change the oil and filter later today and install a battery to see if this thing will crank at least - check for spark, too.  It was not locked up at any piston and I've had oil in the cylinders since last week so hopefully things will not scuff the cylinder or piston too badly.

Rick

   

[rb550four]

Yes, back off the adjusting nuts ,loosen both cables from their perch and remove them from the carb.
Badly varnished pins and such don't take kindly to brute force or hammer tapping. Try a hairdryer before force. heat up the area on the carb you're working on , it'll loosen up the varnish, may take a few trys to get it working freely , keep the heat on it and remove the parts gently.
 Do not use a screwdriver to force slides open.Use hairdyer again or soak in carb cleaner.
Use hairdryer in the pins too, for a while, this may require a light tap with a loose pin to get it sliding or a brass needle from your slides( you'll need a rebuild kit anyways) Tap very lightly  use penetrating oil and heat to make it slide, no hammering.
  If you want to see the piston move why not take the plugs out and bump it, or turn it by hand on the generator side. Was this engine ever seized once before?
Save the starter and battery till you have some clean carbs back in her, that will be worth the wait, You can hear it run then.

[b52bombardier1]

That's  good to know on disconnecting these as an assembly. I will do that tonight.

The slide for number 3 and number 4 finally came loose with continued soaking and tugging with the throttle cable. A little spray oil in there has all of the slides moving easily but the throttle return is nonexistent.  Gotta' work on that for sure.

These carbs need to be boiled to clean them up but I'm very reluctant to break them apart individually. After I get them detached and the slides removed I will see what kind of deep pan I have for boiling. I have used CLR bathroom cleanser for previous Honda carbs but I have heard that lemon juice is good.

The fuel tank is recovering nicely with some naval jelly inside but I will hit it with the boiling CLR and more tumbling with nuts, bolts and washers etc. inside for the rest of the week. I ordered the silver gray POR15 kit last night to  permanently cure it of rust problems.

Yes, I think you are correct and I will hold off on seeing if it will crank. The engine has never seized and I am the second owner. The first owner was my ex boss and he would have told me of any such issue with the bike. He removed the battery which was a good thing but this is the worst old fuel mess I have ever dealt with.

Rick

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[rb550four]

Sorry, I forgot that this a 500, I had 650 on the mind, no kick start there but you have one . Why not give the kick start a try and see if it'll turn over freely?plugs out. Go slowly at first so if you have a stuck you'll feel it before you bend it.
 You know that CLR is an acid right? Just saying, may be strong for cleaning carbs.
Some guys use a lemon juice boil (still acid not as strong as CLR), some guys use pine sol  it loosens up the crud and cleans but leave it in too long the carbs get dark, I like mineral spirits or turpentine to break down the vanish first then a bath in a gallon of carb cleaner makes them bright...you know , what ever you like.
  I always used por 15 black , works great but can't see a freaking thing down the hole afterwards....didn't know they had silver /grey. will do that next time.

[b52bombardier1]

I noticed some ignition key wiring today that had some non Honda electrical tape wrapped around it.   Looks like I have figured out why the ignition key code does not match the seat latch key code.   Not only does it not match but the repair used wire that is too thin and two of the four wires has melted a little.  I have plenty of wire in the correct color / gauge and probably the correct stripe to make these repairs and make it look factory.

  Should I pursue an original 1972 OEM Honda ignition switch or will one of the low-priced aftermarket switches be sufficient? Or just repair it myself?

Many thanks,

Rick

[b52bombardier1]

Hello,

   I got the bad wiring noted above fixed yesterday and got it all spliced in with the correct thickness of wire and wrapped correctly.  It looks almost factory.

  So I connected up the battery for the first time after that to see how things would do.  I knew that the electrical system was not in too bad of a condition because I had powered up the bike once before on a high capacity 15 amp power supply.  Most things worked but 15 amps is not enough to spin the starter.  The starter button on the right handlebar has not looked or felt normal - it has no "push" to it.  It's just "there" and the starter does not spin when the button gets pushed.   But the starter does spin when the solenoid posts are crossed so I know the starter is good.   Now I just need to figure out the starter button and maybe if its a wiring problem.

  I also got the master cylinder removed today.  After many days of soaking, I also got the plunger inside freely moving.  But does anybody have any suggestions on how to get that snap ring out? Do I need the special tool called for in the shop manual?

Many thanks,

Rick   

[rb550four]

   Allot of times there is crud, oxidation at the button, interference with direct contact when pushed or a broken yellow /red wire in the handlebar control. Easy enough to track down, not always an easy fix if PO considered himself a genius and cut the wires close ( no wires-no problem....happens allot) but is either repairable with some work or replaceable from ebay or someplace else. It's all fun and games you know.
  as for the MC snap ring, I use to use altered needle nose plyers, then found a set of snap ring plyer that work both ways and extend from Napa. Been using them ever since... it's all a fishing expedition in a tiny hole, plenty of fun.I have found times where the rebuild kit is more $ than an aftermarket MC and just went with the aftermarket...usually not the best quality but works fine, no need to rebuild that aftermarket MC later on, it's cheap enough to buy another new one. But i f you're a man that won't give up on stock parts...you'll have to work at it.

[b52bombardier1]

That David Silver Spares new aftermarket master cylinder is looking better and better but I need to put a caliper on my handlebars first for a thickness measurement.  I think its 7/8ths of an inch but need to make sure. And buying the snap ring pliers recommended in the FAQ does not seem like a good idea because this might be the only time I ever use it.

  I do want to repair that right handle switch pushbutton because it looks like a lot of work to assemble a new one.  The throttle cable and handle also need to be cleaned because there's no cable return action to get things back to idle.   

  But thanks for the advice . . . I can use every bit of it.

Rick

[b52bombardier1]

Hello,

   Does anybody know if a September 1971 CB500 was intended to use a center stand?  The parts book certainly thinks one should have been available and mounted on my bike but it was not there when I got it.   So I found one with the spring and that crescent shaped piece on Ebay and finished the last coat of paint for it all last night. My bike has the mounting brackets on the bottom of the frame and getting the big pieces installed was easy.  But the crescent shaped piece is puzzling.

  I checked the photo gallery here but there are no good pictures of where the top hole in the crescent shaped piece mounts.  The parts diagram is also not much help.  Any clues would be very helpful.

Thanks,

Rick

[b52bombardier1]

With 3.2 quarts of fresh oil in the crankcase, with a little oil in each spark plug hole, with some oil poured through each valve cap and after 30-40 seconds of vigorous cranking using the starter to circulate that fresh oil . . . . wait for it a little more . . . all four cylinders roared to life for the first time tonight since the middle 70's.  Man, was that ever a happy sound for me!!

  This was done with very small bursts of carb cleaner and starting ether.  The carbs are still in work but at least I now know that spark, compression and ignition timing are all good.  Given how rough starting fluid can be on cylinder wall oil film, I won't be doing this again.  But this was a huge burst of progress tonight.

  I just have to figure out why the starter pushbutton does not work but that'll be for tomorrow night maybe.

Rick

[Restoration Fan]

Great news!
It's running so now you just have to get the carbs synched up and it'll be time for some riding!

[b52bombardier1]

Hello,

  As RB550Four mentioned above, my starter pushbutton was dirty. I took the halves apart and cleaned it with electronic contact cleaner and blew it clean with compressed air.  Its working fine now.  I don't have to replace that right side switchgear anymore.

Rick

[JetgreenK1]

Rick,

My first process is to buy stock in simple green and just soak them for at least 24 hours. If you have a parts cleaner the process is advanced rapidly. I found that the float pin comes out best with a gentle dead blow hammer after a good soaking in simple green. As for the slides the same applies. However mine weren't stuck as bad as yours. Hope this helps.  Once it is all done, Mother's Aluminum polish does wonders on the float bowls to bring them back to shiny new looks. 

[b52bombardier1]

Hello,

  And a question:   Will vigorous cranking of the engine with the electric starter eventually pump a visible flow of oil to the top end of the engine?  Will I see an oil flow through an open valve cap?

  I'm not seeing any now but the oil pressure light goes out within about two seconds.

Many thanks,

Rick

[b52bombardier1]

Hello,

  And very, very good news tonight for a bike that has not really ran since the late 70's.   She runs and runs well.  Starts easily and idles nicely.  Though it is still sitting on the center stand - not ready to ride until tomorrow. After mounting my freshly rebuilt carbs, I tightened them to my still original rubber manifolds. I dribbled some fuel into the carbs and sprayed a little starting fluid into the throat of each carb . . . . and hit the starter button. No fuel tank or air box until tomorrow also.

  It took maybe fifteen seconds of vigorous starter cranking but the motor slowly came to life and settled into a steady 3000 rpm-ish idle. With the valve caps all removed, I got oil splash and flow out each hole, more so on 1 and 4 but I could see oil movement through all eight cap holes.  It took me a few seconds to find the idle adjustment knob and I dialed it down to maybe 1100-1200 rpm.

  I had my Fluke multimeter probes on the battery posts and saw 14.4 volts DC at that initial 3000 rpm setting.  Then I flipped the multimeter knob to AC volts and had around .02 to .04 volts AC at the battery - a tiny amount. The headlight is unplugged so these DC voltages may drop somewhat but this will be easy to re-connect tomorrow.

  It is midnight here so I could not run it very long without upsetting the neighbors but the throttle response was also good. The four into two Jardine header sounds good, too. I will check the pipe temperatures tomorrow with my infrared thermometer and see if they are all about the same. I will also take a peek at the points to see if they are arcing and sparking more than normal.

  I will mount the tank and airbox tomorrow but I need to get some 3/16ths fuel line and maybe a few other things.

  Question - it was unclear to me how the fuel lines were supposed to run when I took the tank off. And I can't find any good pictures in the books or around here but it would certainly appear that I'm missing some fuel line "Y" fittings.  Am I missing two of these to join the two petcock pipes into one and then another Y to split that one back into two for the two carb fuel lines? I just think I must be missing something here . . .

  Hopefully, I can ride it tomorrow but it will be short slow trips around the neighborhood because my front brake master cylinder does not get here until Monday. Now I'm curious about the clutch and transmission.

Rick