Topic: fmctm1sw: 1981 CB650 custom AKA The Nifty 650

[fmctm1sw]

Well, I promised myself I wouldn't have too many bikes tore apart at once but I just can't help it.  As mentioned in another post, I picked this up off CL for $250 (with title).  Supposedly this bike was used as a payment for work done instead of cash.  I was told the guy tried to use it for "enduro riding."  (Thankfully) it died and was returned back to the guy I bought it from.  I knew right away the carbs were frozen.  Plastic controls are pretty baked from the sun too.  I decided to remove the carbs and bypass the ignition switch and try to get a compression test done.  After jumpering the ignition switch, I got the oil light and neutral light.  Headlight was good too as was the brake light.  Turns signals a little iffy though:  No blinking and the front ones didn't seem to light up.  They look faintly lit at all times though.  The carbs were a real challenge to get off.  Those rubber boots between the head and carbs were in horrible shape.  I eventually forced them off with the help of a tie down strap.  I'll dig into the carbs later. 

After jumping the bike to my truck, I hit the start button and got a big "CLICK."  That was it...  I bypassed that and connected the cable to the starter motor and it turned over.  Got all the plugs out and ended up between 80-110 on all the readings.  Disappointing but not surprising.  I'll get the carbs cleaned up and run it for a while before I do anything drastic.  I shorted the starter relay and I have spark on all 4 plugs!  Hopefully, with a minimal investment, I can get it started and go from there.

So far, I reckon I need...  carb dissassembly and cleaning (one of the slides is frozen), new choke cable, ignition switch (or key), intake rubbers, and starter relay.  Oh, and tires when I get that far.  And brake work too...

[fmctm1sw]

Carbs are about to be a go.  Need new accelerator pump but slides all freed up.  Here's a before and after.

[fmctm1sw]

My home computer is on the fritz so I can't post pictures yet but I cleaned up the engine a little.  I found out (probably) why the turn signal isn't working (cut wire) and possibly why the bike stopped running.  The vacuum line to the fuel pump was cut and the other vacuum line had a nail stuck in the bottom of it.  Obvious signs of desperation by someone unfamiliar with operation of the carbs.

[fmctm1sw]

Here's some befores and afters of the motor.  Not trying anything drastic, just wanted the rear of the engine clean for when I get the carbs back onto it.

[fmctm1sw]

Some real quick work on the chrome to see what would happen.  Should clean up ok...

[fmctm1sw]

Some signs of neglect and/or a PO not understanding what he was doing.  You can see why the front right turn signal doesn't work.  And that is a nail shoved into one of the tubes that comes from the fuel pump..     And also the air box.  Not correctly fitted.  Not life and death but....

[fmctm1sw]

I've been chipping away at this.  I got my new carb insulators from motogrid and I got the accelerator pump and a set of bowl gaskets from Cycle Recycle.  I found one of the bowl drain screws was eroded at the tip though so I'll need a new one of those.  I shot some carb cleaner into each of the intakes and they all fired.  I cleaned the bowls real good and put the carbs back on.  Getting the throttle cables back on was a PITA.  Unfortunately, the throttle doesn't return very well.  I know the carbs themselves spring back well.  I had this happen bofore and I found the throttle tube and handgrip were all gunked up so hopefully that's all it is.  Today, I plan on taking the switch apart and verifying the throttle cables aren't binding up...

*edit*  I had a spare starter relay laying around too.  That fixed the issue with the starter.

[fmctm1sw]

Update.  I cleaned up the throttle tube real good but it made no difference.  I noticed that if I disconnect the throttle return cable, it snaps back well.  I got some fuel line today and connected my 350F tank up to it.  I got the bike started and it ran... on two cylinders      I had fuel pouring out of what appears to be the airbox at cylinder #3.  Pipes 1 and 3 cold.  Oh well...  off comes the airbox again.

[fmctm1sw]

Well, it's officially a runner.  I got the carb passages cleaned out and the overflow was a sticking float.  Cylinder 1, 3, and 4 were nice and hot but #2 was only warm.  It was also backfiring a little.  I took the spark plug out of #2 and it fell apart!  I'm going to get a fresh set of plugs in it and proceed.  The throttle is snapping back better too.  I connected the cables BEFORE I mounted the carbs this time...   much easier..  It's LOUD.... holy crap.  Idle was kind of all over the place too.  Once I get good firing on all the cylinders, I'll track those issues down..

[hoodellyhoo]

Congrats! I'm enjoying seeing how you clean this bike up.

[WhyNot2]

I am watching too......wish I could come across deals like that here...............

[fmctm1sw]

Update.  The fuel I described as coming from the airbox wasn't coming from the airbox at all.  The fuel pump was malfunctioning and shooting gas out of the vent tube all over the airbox.  I had the carbs back off and I aligned all the throttle slides real close.  I paid absolutely no attention to this when I first went through them.  I got it started and idling ok, all the pipes are hot.  I put a new clutch perch on it too, the old one had worn out around the pivot screw and had a lot of slop in the lever.  Compression came way up too.  Next is the brakes.  Oh I need a battery as well...  But a runner at this point..

[cb650]

Good start.   Get a starter cover off a 79.  They are chrome.

[fmctm1sw]

Good start.   Get a starter cover off a 79.  They are chrome.

Thanks.  That thing is hideous...

[F16Viper68]

Update.  The fuel I described as coming from the airbox wasn't coming from the airbox at all.  The fuel pump was malfunctioning and shooting gas out of the vent tube all over the airbox.  I had the carbs back off and I aligned all the throttle slides real close.  I paid absolutely no attention to this when I first went through them.  I got it started and idling ok, all the pipes are hot.  I put a new clutch perch on it too, the old one had worn out around the pivot screw and had a lot of slop in the lever.  Compression came way up too.  Next is the brakes.  Oh I need a battery as well...  But a runner at this point..

I was able to get my compression up on  my 1981 CB650C by simply adjusting the valves.  I had the #1 reading 90 psi and got it up to 150 by simply adjusting the valves correctly. 

You're right btw our bikes do look similar.  Going to try to get #3 firing this weekend.

Dave...

[fmctm1sw]

I think brakes are my new (if I ever had one) worst thing to work on.  I ALWAYS make a mess.  Simply bleeding them is adventure for me to say nothing of popping out frozen pistons.  So I picked up a master cylinder from  a member here and completely disassembled it for cleaning.  It wasn't frozen but pretty gunked up.  By the time I was done it was spotless...   but didn't work.  It just never built up any pressure.  All the passages were clear.  After fighting that for a while, I put the master cylinder off my 550 on it to get to the calipers.  The pistons were frozen of course.  I got the left side tore down and cleaned up.  The piston didn't look too bad.  I got it back together and started bleeding it and the connections leaked.  After some tightening, I decided to pop the other caliper off.  Unfortunately, all that bleeding and squeezing I had done on the master cylinders had the caliper clamped on to the disk for dear life.  After some pounding with a rubber hammer, it finally came off.  Got it apart and the piston is cratered.  No chance of reusing that one.  I was granted temporary relief from this misery by my truck which had developed a flat tire somehow. 

[F16Viper68]

I'm beginning to think the same guy owned both our bikes.

I just finished my forks so next are the calipers and master cylinder (parts enroute).

[fmctm1sw]

I cleaned out the tank the best I could with toilet bowl cleaner.  I don't like the lining job but I'm willing to try to live with it as long as it stays together.  I added an inline fuel filter to be safe(r).  It still needs brake work but other than a battery and a choke cable, I should be able to get it to the end of the street for an op test.

[lucky]

This work is the same reason many of us got out bikes.
Neglect,ignorance,etc.,.

[F16Viper68]

I cleaned out the tank the best I could with toilet bowl cleaner.  I don't like the lining job but I'm willing to try to live with it as long as it stays together.  I added an inline fuel filter to be safe(r).  It still needs brake work but other than a battery and a choke cable, I should be able to get it to the end of the street for an op test.

What did you line the tank with?  Knock on wood the POR-15 process worked for me.

Dave...

[F16Viper68]

For what it's worth, my first compression test was also disappointing but once I adjusted the valves everything checked out great! Maybe give it a shot? 

Dave...

[fmctm1sw]

I cleaned out the tank the best I could with toilet bowl cleaner.  I don't like the lining job but I'm willing to try to live with it as long as it stays together.  I added an inline fuel filter to be safe(r).  It still needs brake work but other than a battery and a choke cable, I should be able to get it to the end of the street for an op test.

What did you line the tank with?  Knock on wood the POR-15 process worked for me.

Dave...

Looks like they used Kreem.  I thought about trying to strip it out and reline it but figured I'd wait to see how it runs.  I did a POR15 job on one of my 350Fs three years ago and I am very happy with it.  So maybe after I see it run for a while, I'll POR strip it and redo it...   maybe..   Compression came up pretty good even with that short 5 minute idle I did with it.  Should be all good there too.  I prefer the old "standard look" to the cruiser shape of it but it's kind of growing on me...

[wedoo2]

I have done a couple of Custom restores, both 750s.  Never one in the shape yours is in, but still all of the same kind of problems.  The last one I did came out looking real nice but it irritated me riding the bike as I always wanted to shift up a gear that wasn't there.  They were DOHCs and you know the problems with valve adjustment.  Not the same deal at all.

You have the right temperament for this it seems.  Taking it slow with realistic expectations.

[fmctm1sw]

You have the right temperament for this it seems.  Taking it slow with realistic expectations.

Temperment yes, funding no   I've really slacked over the past couple months   I got tied up with the holidays and a DIY spot welder project I'm trying to pull together.  Plus the garbage disposal and dishwasher gave up on  me.  Going out today and looking for a battery and oil filter for it.

[fmctm1sw]

Not even a simple oil change can go smoothly with this.  In addition to a completely black filter, the only components consisted of what is photoed (cleaned before photo).  No spring much less one of those elusive seating washers.  Not only that, what was there wasn't even assembled in the right order.  Luckily I had a spring laying around and a NOS seating washer.  Oil changed now and all assembled correctly.  Fully charged battery too.  Tomorrow should be "cleaning/starting" day.