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Author Topic: 1981 CB650C aka "The Titanic's Anchor"  (Read 55912 times)

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Offline F16Viper68

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1981 CB650C aka "The Titanic's Anchor"
« on: November 06, 2011, 05:11:35 PM »
Let me introduce you to my latest project, a 1981 Honda CB650C which has 8,500 miles on it.  I picked her up about a month and half ago in Tallahassee, FL after seeing posted a few times on Craigslist.  A few hundred bucks and a trailer ride later she's home!  According to the previous owner she hadn't run in "a while" which from what I can tell from the registration and license plate means not in ten years.









As you can see from the pictures below the gas tank is pretty much shot.  I've since picked up a different tank on eBay and it's currently out in the garage having just been treated with POR-15.  What a process that is...





A few weeks ago I pulled the carb rack (fun), cleaned out the float bowls, jets (as best I could), re-assembled, manually rotated the engine (wasn't bound), changed the oil/filter, and the spark plugs.  After rigging up a temp gas tank I was able to get it running.  Barely.  It would only run on full choke and at about 2,500rpm.

I ordered and installed carb rebuild kits taking special care to ensure the slow speed jets were clear.  I got everything back together and it ran better but it still wouldn't run off choke unless the air cleaner assembly was installed. I read that interesting tidbit somewhere on here (thanks!). 

Yesterday I got the idle steady at 1,500rpm off choke. On a whim I took infrared heat readings off the exhaust tubes as they exited the engine.  The #3 tube was reading 130 degree while the rest were in the low 200's.  Hmmmm.  Decided to call it a night. 

Dave...
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Offline F16Viper68

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Re: 1981 CB650C aka "The Titanic's Anchor"
« Reply #1 on: November 06, 2011, 05:31:11 PM »
Today I decided before going further I needed to perform some basic trouble shooting before ripping the carbs apart again.  I got it running and stable at 1,500rpm. I was able to verify the #3 wire was providing spark (wire/screw driver/cylinder head = spark)  I tried it again with the sparkplug out of the engine but attached to the wire.  Yep the spark is good.  Off to test compression. 

When I first bought the bike I knew one of the first things I should check was compression but I discovered my automotive compression gauge didn't have the adapters necessary to test this bike so skipped this step.  Well time to revisit this check.  Off to Advance Auto to pick a gauge with all the necessary adapters ($41.00).

First test, hooked up the battery charger to ensure consistent cranking speed, locked the throttle full open, and cranked away.  I got the following readings:
#1= 90 psi
#2 = 130 psi
#3 = 130 psi
#4 = 130 psi. 

Ummm.  Wasn't expecting that.   :-\  I dump a bit of oil into #1 and it went up to 95.  Well it's not the rings. 

Ok, I needed to check the valves anyways.  Long story short, every single valve was tight except the #2 intake.  Arrrrrrghhhh!!!  Adjusted everything and got 150 +/- 5 across all four cylinders.  Whew.  Fingers crossed no long term damage was done by the tight valves. 

I got it all put back together and decided to see if I could inject some starting fluid into the #3 carb to see if the cylinder would fire.  I found a screw on the right side of the carbs that opens a small hole into the carb (runs awful with the screw out).  I sprayed some fluid in the hole and the cylinder seems to fire up briefly. 

Well I guess it's time to pull the carbs again.   



« Last Edit: November 06, 2011, 06:25:35 PM by F16Viper68 »
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Offline F16Viper68

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Re: 1981 CB650C aka "The Titanic's Anchor"
« Reply #2 on: November 06, 2011, 06:02:16 PM »
Does anyone know if this sissy bar is stock?  I was going to remove it but everyone who has seen this bike comments how much they love the sissy bar so it's probably going to stay.

Dave... 

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Offline onepieceatatime

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Re: 1981 CB650C aka "The Titanic's Anchor"
« Reply #3 on: November 06, 2011, 10:55:27 PM »
Are you planning to restore the bike, modify it, or just get it to a safe, reliable, running condition?
I am pretty certain the sissy bar is not stock.
It looks like a broken turn signal lens on the front. I may have one in the garage if you are interested, I can check in a couple of days.
You may also want to check out http://www.hondacb650.com/index.php for a lot of good information on the CB650.
Roy
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Offline trueblue

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Re: 1981 CB650C aka "The Titanic's Anchor"
« Reply #4 on: November 07, 2011, 03:09:14 AM »
http://www.myhonda650.com/index.htm Another site with lots of good info, I wish I could lay my hands on a 650c, my missus want's one, I have a 650z but it is too high in the seat for her to feel comfortable, so for now she is stuck with her 250 virago.
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Offline F16Viper68

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Re: 1981 CB650C aka "The Titanic's Anchor"
« Reply #5 on: November 07, 2011, 08:50:43 AM »
I'm having a lot of trouble trying to post and reply to posts.  90% of the time the Captcha isn't accepting my inputs.  When reply to a post with an external link in it states I can't post external links?!?!!  Well obviously you can.  But I can't? 

Does the captcha thing go away after X amount of posts?  Because if not, this site just became read-only to me.

Dave...
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Offline trueblue

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Re: 1981 CB650C aka "The Titanic's Anchor"
« Reply #6 on: November 07, 2011, 12:38:11 PM »
I think it goes away after 5 posts, and you can then post external links as well
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1979 CB650Z
Nothing can be idiot proofed, the world keeps producing better idiots.
Electronic Guages for your SOHC 4

Offline fmctm1sw

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Re: 1981 CB650C aka "The Titanic's Anchor"
« Reply #7 on: November 07, 2011, 01:25:10 PM »
Reminds me of my 650C project.  The sissy bar is not stock, but that looping rail part behind the seat is.  The inside of your tank looks like mine.  The idle jets are pressed in and can be tough to clear the whole way.  I found one of mine was blocked when I inserted a individual wire strand into it and noticed it didn't go down as far as the others.  I also developed a system where I attached a tube to the passage where the idle mixture screw is and blew into it, noting where I heard and/or felt air.  Lucky you saw it before I did, I may have made a trip for that.  I could use a decent exhaust.  I got it started up finally last weekend on a donor tank as well... 

P.S.  Your description of those screws that open to the carb may be the balancing ports.  As you noticed, you need to keep them closed.  Carb #2 doesn't have one as it goes to that fuel pump that has vexed me.  Does yours work?
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Quote from: 754
Dude is that a tire ? or an O-ring..??

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This is not a pod thread
This is not a #$%* on my vacuum gauges thread
This is a help or GTFO thread.

1973 CB350F
1973 CB350G
1975 CB550K
1983 GL650I
1973 CB750K3 (http://forums.sohc4.net/index.php?topic=92888.0)
1984 Kawasaki KLT-250 (AKA 3 wheeler of death)
1994 Honda TRX300
1999 Honda TRX250

Offline cb650

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Re: 1981 CB650C aka "The Titanic's Anchor"
« Reply #8 on: November 07, 2011, 01:53:35 PM »
FYI the 82 had screw in idle jets.     Mostly the same carb as 81.
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Offline F16Viper68

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Re: 1981 CB650C aka "The Titanic's Anchor"
« Reply #9 on: November 07, 2011, 03:57:29 PM »
Quote from: fmctm1sw on November 07, 2011, 01:25:10 PM
Reminds me of my 650C project.  The sissy bar is not stock, but that looping rail part behind the seat is.  The inside of your tank looks like mine.  The idle jets are pressed in and can be tough to clear the whole way.  I found one of mine was blocked when I inserted a individual wire strand into it and noticed it didn't go down as far as the others.  I also developed a system where I attached a tube to the passage where the idle mixture screw is and blew into it, noting where I heard and/or felt air.  Lucky you saw it before I did, I may have made a trip for that.  I could use a decent exhaust.  I got it started up finally last weekend on a donor tank as well... 

P.S.  Your description of those screws that open to the carb may be the balancing ports.  As you noticed, you need to keep them closed.  Carb #2 doesn't have one as it goes to that fuel pump that has vexed me.  Does yours work?

I really thought I got the slow speed passages cleared but obviously not.  I don't think #3 was firing for some time.  If you look the photo below you can see the #3 exhaust is a lot more rusted than the other pipes.  I'm guessing this is because it wasn't getting hot?   



By fuel pump do you mean the vacuum petcock aka The Son of Satan (SOS)?



If so, I removed it and put a vacuum cap on the #2 carb port.  I now run the fuel line direct from the temp tank to the fuel input on the carb rack.  Works great.  I'd post a link to the PDF I found on rebuilding carbs that explained how to bypass the SOS but I can't post external links yet.   ;D

The screw/port I'm talking about is the one below.  Is that the balancing port? 



Dave...


« Last Edit: November 07, 2011, 04:09:13 PM by F16Viper68 »
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Offline F16Viper68

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Re: 1981 CB650C aka "The Titanic's Anchor"
« Reply #10 on: November 07, 2011, 04:04:22 PM »
Quote from: onepieceatatime on November 06, 2011, 10:55:27 PM
Are you planning to restore the bike, modify it, or just get it to a safe, reliable, running condition?
I am pretty certain the sissy bar is not stock.
It looks like a broken turn signal lens on the front. I may have one in the garage if you are interested, I can check in a couple of days.
You may also want to check out http://www.hondacb650.com/index.php for a lot of good information on the CB650.
Roy

My short term goal is to simple get it as you say, "safe, reliable, and in running condition".  Once that happens I'll start the process of making it presentable again. 

Thanks for the offer but I actually have a replacement already sitting on the work bench.  I decided not to swap it out till I get all major maintenace done. 

Dave...
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Offline F16Viper68

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Re: 1981 CB650C aka "The Titanic's Anchor"
« Reply #11 on: November 07, 2011, 04:06:53 PM »
Quote from: trueblue on November 07, 2011, 03:09:14 AM
http://www.myhonda650.com/index.htm Another site with lots of good info, I wish I could lay my hands on a 650c, my missus want's one, I have a 650z but it is too high in the seat for her to feel comfortable, so for now she is stuck with her 250 virago.

Thanks for the link.  I think Dave's site was the first one I found when I started researching the CB650.   :)  I think half the fun of fixing up this bike is surfing. 

Dave... 
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Offline F16Viper68

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Re: 1981 CB650C aka "The Titanic's Anchor"
« Reply #12 on: November 07, 2011, 04:07:26 PM »
Quote from: trueblue on November 07, 2011, 12:38:11 PM
I think it goes away after 5 posts, and you can then post external links as well

Whew. You're right it does go away after five posts.

Dave...
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Offline F16Viper68

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Re: 1981 CB650C aka "The Titanic's Anchor"
« Reply #13 on: November 07, 2011, 04:08:04 PM »
Quote from: cb650 on November 07, 2011, 01:53:35 PM
FYI the 82 had screw in idle jets.     Mostly the same carb as 81.

Oh that would be sooo nice.

Dave...
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Offline F16Viper68

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Re: 1981 CB650C aka "The Titanic's Anchor"
« Reply #14 on: November 07, 2011, 04:30:59 PM »
Well one thing I've learned during this project is that chrome pieces I thought were junk can be cleaned up nicely.

Before:


After:


The before is the left side engine guard and the after is the right side but they were equally rusty before I started.

During my surfing I found a thread on how to use Oxalic Acid to remove rust from chrome.  You can read the thread by clicking here.  The thread is 37 pages long so if you're a trusting soul you can read below where to obtain some oxalic acid.     :)

I found a product called Goof Off at my local ACE Hardware that contained oxalic acid.  I bought two gallons and started soaking a few test pieces in the acid bath.  Every so often I hit them with a brass brush and so far, so good.  The longest I've left a piece in is 24 hours.   



Dave...
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Offline cb650

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Re: 1981 CB650C aka "The Titanic's Anchor"
« Reply #15 on: November 08, 2011, 01:07:31 AM »
Yes those are the vacuum ports.   #2 should go to the auto fuel shutoff.  I remove it on all mine and plug the port.
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Offline F16Viper68

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Re: 1981 CB650C aka "The Titanic's Anchor"
« Reply #16 on: November 08, 2011, 04:26:28 AM »
Quote from: cb650 on November 08, 2011, 01:07:31 AM
Yes those are the vacuum ports.   #2 should go to the auto fuel shutoff.  I remove it on all mine and plug the port.

Yeah I did the same thing based on the article I found in this PDF.  http://www.cb750c.com/publicdocs/SeanG/Honda_Carb_Manual_revD.pdf

Dave...
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Offline F16Viper68

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Re: 1981 CB650C aka "The Titanic's Anchor"
« Reply #17 on: November 10, 2011, 03:37:23 PM »
I'm in the process troubleshooting why my #3 cylinder is not firing and have a question.  Do any of  you know any way to tell if it's firing besides removing the sparkplug wire and observing a drop in RPM's?

Dave....
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Offline scunny

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Re: 1981 CB650C aka "The Titanic's Anchor"
« Reply #18 on: November 10, 2011, 06:00:43 PM »
pipe should be hot.
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Offline fmctm1sw

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Re: 1981 CB650C aka "The Titanic's Anchor"
« Reply #19 on: November 10, 2011, 06:06:28 PM »
Quote from: F16Viper68 on November 10, 2011, 03:37:23 PM
I'm in the process troubleshooting why my #3 cylinder is not firing and have a question.  Do any of  you know any way to tell if it's firing besides removing the sparkplug wire and observing a drop in RPM's?

Dave....

Pull the plug out and ground it against the head somewhere.

BTW, there was a guy selling a 1980 650 in Tallahassee on CL.  Someone bought it before I could get him to pull a few things off it for me.  Not you by any chance?
« Last Edit: November 10, 2011, 06:08:54 PM by fmctm1sw »
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Quote from: 754
Dude is that a tire ? or an O-ring..??

Quote from: inkscars
This is not a pod thread
This is not a #$%* on my vacuum gauges thread
This is a help or GTFO thread.

1973 CB350F
1973 CB350G
1975 CB550K
1983 GL650I
1973 CB750K3 (http://forums.sohc4.net/index.php?topic=92888.0)
1984 Kawasaki KLT-250 (AKA 3 wheeler of death)
1994 Honda TRX300
1999 Honda TRX250

Offline F16Viper68

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Re: 1981 CB650C aka "The Titanic's Anchor"
« Reply #20 on: November 10, 2011, 06:17:55 PM »
Quote from: fmctm1sw on November 10, 2011, 06:06:28 PM
Quote from: F16Viper68 on November 10, 2011, 03:37:23 PM
I'm in the process troubleshooting why my #3 cylinder is not firing and have a question.  Do any of  you know any way to tell if it's firing besides removing the sparkplug wire and observing a drop in RPM's?

Dave....

Pull the plug out and ground it against the head somewhere.

BTW, there was a guy selling a 1980 650 in Tallahassee on CL.  Someone bought it before I could get him to pull a few things off it for me.  Not you by any chance?

Nope but I did email him about it. I was going to buy what was left but I didn't see anything on it that was in better shape than my current mess.   ;D

Dave...
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Offline F16Viper68

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Re: 1981 CB650C aka "The Titanic's Anchor"
« Reply #21 on: November 10, 2011, 06:19:53 PM »
Quote from: scunny on November 10, 2011, 06:00:43 PM
pipe should be hot.

Yeah that's how I actually discovered it wasn't firing.  Infrared temperature gun. 

Dave...
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Offline F16Viper68

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Re: 1981 CB650C aka "The Titanic's Anchor"
« Reply #22 on: November 13, 2011, 01:50:37 PM »
I spent this weekend rebuilding a carb rack I bought off a parts bike since it was cosmetically in much better shape than the rack that came with this bike.  I disassembled the carbs but did not break apart the rack.  Then I soaked the entire assembly in a bath of Pine Sol overnight.  This morning I rinsed everything with the hose, blew it dry with compressed air, and ran carb cleaner through everything. 

FYI...while I had everything apart I replaced the standard stuff with a rebuild kit (float bowl, gasket, main jet, idle mixture valve, etc) 

I think it came out pretty nice considering the rack is thirty years old.









The bike fired right up once I got everything reinstalled but it was only running on #1 and #2.  I did some basic troubleshooting and then everything was working except #1.  Sigh.  More testing (spark, clean plug, etc) and all four are firing.

Question - Why do some cylinders run hotter than others (like 125 degrees on #1 and 225 degrees on #3)?  Is that mixture?  I set the pilot jets at 2.5 turns so I wouldn't think there wouldn't be that much of a difference. 

Dave...
« Last Edit: November 13, 2011, 02:00:55 PM by F16Viper68 »
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Offline Emokid

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Re: 1981 CB650C aka "The Titanic's Anchor"
« Reply #23 on: November 13, 2011, 02:06:54 PM »
Hey , nice rack  ;D
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Offline F16Viper68

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Re: 1981 CB650C aka "The Titanic's Anchor"
« Reply #24 on: November 15, 2011, 08:14:20 PM »
The fun continues... 

I just spent the past few hours trying to figure out why the sucker wasn't charging. The previous owner mentioned it wasn't charging when he parked it years ago.   

So I decided to start troubleshooting tonight.  Between the service manual and  http://www.electrosport.com/media/pdf/fault-finding-diagram.pdf I discovered the stator was shorted to ground. 

I removed the primary and stator/rotor cover (?) to check the bushings and rotor.  The rotor ohm'ed check good and bushings look ok.  Checked the readings for the stator again and the short was gone.   :o

I started looking at the wiring and noticed the wiring had been crushed by the primary cover.  I'll see if it's repairable later in the week.  I can't believe this didn't kill the R/R but it checks good by the DVM.   



Dave...

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