Author Topic: CB650 Custom Rust Bucket  (Read 11266 times)

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Offline CarbonK

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CB650 Custom Rust Bucket
« on: August 11, 2018, 02:25:46 PM »
Thought I’d start a thread on a 1982 1981 CB650 Custom I picked up earlier this week. It’s not running, not pretty, and rusty. The plan for now is to get it running and it looks like I have my work cut out for me. Here are some pics.







« Last Edit: December 02, 2018, 10:01:19 AM by CarbonK »

Offline cb650

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Re: CB650 Custom Rust Bucket
« Reply #1 on: August 11, 2018, 10:06:59 PM »
Looks like a lot of WORK!!  LOL      lots of mismatched parts.   FYI there was no "custom"in 82 they went to the nitehawk.  None of the cosmetic parts interchange.   
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Re: CB650 Custom Rust Bucket
« Reply #2 on: August 11, 2018, 10:48:17 PM »
Looks like a lot of WORK!!  LOL      lots of mismatched parts.   FYI there was no "custom"in 82 they went to the nitehawk.  None of the cosmetic parts interchange.

He's probably referring to the SC.  1982 also included the last run of the sohc 650.
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Offline CarbonK

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Re: CB650 Custom Rust Bucket
« Reply #3 on: August 12, 2018, 07:45:36 AM »
Whoops, my bad. It’s an 81.

Turned the key yesterday with a fresh battery and nothing went on which didn’t surprise me. Checked fuses, cleaned up some connections and made sure everything was in order for the most part. Turned the key and we have lights! No engine turn over though.
Removed the carbs and airbox to get a little more room, boy these carbs are bad. Choke is frozen, throttle is frozen, and is that caulk on one of the vent tube openings? Lol.



Gonna put these aside for now.

Back to getting the bike to turn over. Tested the starter solenoid and start button and they work. Starter motor sadly doesn’t. Pulled the starter motor out and it’s stuck also. Took it apart and thinking of rebuilding it but it may be too far gone. Gonna take a starter I have on hand and put it in, see what happens.
« Last Edit: August 12, 2018, 08:19:34 AM by CarbonK »

Offline CarbonK

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Re: CB650 Custom Rust Bucket
« Reply #4 on: August 12, 2018, 07:50:18 AM »
Looks like a lot of WORK!!  LOL      lots of mismatched parts.   FYI there was no "custom"in 82 they went to the nitehawk.  None of the cosmetic parts interchange.

Yeah, it’ll keep me busy that’s for sure. What are some of the mismatched parts you noticed?

Offline cb650

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Re: CB650 Custom Rust Bucket
« Reply #5 on: August 12, 2018, 03:56:56 PM »
Well first off there was no 82 CUSTOM.    It was a nitehawk (Yes SC) in 82.   Way diff looking.   The  rear shocks are custom.   The wheels are custom but only the 79 {no custom} and 80 {custom} had comstars with a single caliper front brake. Standard models had single disk with wire wheels.  All of this could have been changed over the years.   I even seen on once with a drum front brake.   Exhaust was another diff but your is gone.
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Offline CarbonK

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Re: CB650 Custom Rust Bucket
« Reply #6 on: August 12, 2018, 07:30:07 PM »
Well first off there was no 82 CUSTOM.    It was a nitehawk (Yes SC) in 82.   Way diff looking.   The  rear shocks are custom.   The wheels are custom but only the 79 {no custom} and 80 {custom} had comstars with a single caliper front brake. Standard models had single disk with wire wheels.  All of this could have been changed over the years.   I even seen on once with a drum front brake.   Exhaust was another diff but your is gone.

Yeah, it’s an 81 not an 82, my mistake. I noticed it was missing a caliper and rotor. The bike came with a chrome 4 into 4 but it’s not on it at the moment.

Offline CarbonK

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Re: CB650 Custom Rust Bucket
« Reply #7 on: August 14, 2018, 03:43:15 PM »


What do you guys think? Too crusty for a rebuild?  ::)


Put a starter from a 550 I had inside and....

Engine is stuck. Drained some marvel mystery oil into the cylinders, I’ll see if I can free it up tomorrow.

Offline calj737

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Re: CB650 Custom Rust Bucket
« Reply #8 on: August 15, 2018, 04:24:08 AM »
Engine is stuck. Drained some marvel mystery oil into the cylinders, I’ll see if I can free it up tomorrow.
Mix up some MMO and ATF @ 50/50 then drizzle that into the cylinders. Let sit a few days. Bike in gear (3rd works well), rock the bike back and forth. Usually will get the rings to break free without breaking.
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Offline CarbonK

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Re: CB650 Custom Rust Bucket
« Reply #9 on: August 16, 2018, 11:24:57 AM »
Engine is stuck. Drained some marvel mystery oil into the cylinders, I’ll see if I can free it up tomorrow.
Mix up some MMO and ATF @ 50/50 then drizzle that into the cylinders. Let sit a few days. Bike in gear (3rd works well), rock the bike back and forth. Usually will get the rings to break free without breaking.

Thanks for the tip, went out and added some last night. Gonna let it sit for a couple more days. In the meantime I’m gonna work on the carbs. Was able to crack one floatbowl open after shearing off two heads....



Anyone want some bleu cheese?
Looks like the carbs might be toast. Main jet holder actually crumbled away.
« Last Edit: August 16, 2018, 11:35:12 AM by CarbonK »

Offline CBJoe

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Re: CB650 Custom Rust Bucket
« Reply #10 on: August 16, 2018, 01:13:20 PM »
Engine is stuck. Drained some marvel mystery oil into the cylinders, I’ll see if I can free it up tomorrow.
Mix up some MMO and ATF @ 50/50 then drizzle that into the cylinders. Let sit a few days. Bike in gear (3rd works well), rock the bike back and forth. Usually will get the rings to break free without breaking.

Thanks for the tip, went out and added some last night. Gonna let it sit for a couple more days. In the meantime I’m gonna work on the carbs. Was able to crack one floatbowl open after shearing off two heads....



Anyone want some bleu cheese?
Looks like the carbs might be toast. Main jet holder actually crumbled away.


Holy crap batman!  I've seem some nasty carbs...but thats terrible.  I'm not even sure I understand whats going on there from a chemical reaction standpoint
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Offline calj737

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Re: CB650 Custom Rust Bucket
« Reply #11 on: August 16, 2018, 03:46:40 PM »
Well the good news is you can use 750 round top carbs on your bike. Send a PM to Bill or David Benton for a price on a replacement set.
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Offline Gurp

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Re: CB650 Custom Rust Bucket
« Reply #12 on: August 18, 2018, 11:06:15 AM »
Wow. Those carbs....
slow Progress 74 cb550.

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Offline CarbonK

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Re: CB650 Custom Rust Bucket
« Reply #13 on: August 19, 2018, 11:26:01 AM »
Engine is still stuck, as am I. Trying to get to the pistons but the cam gear is in a way where I can’t get to the other bolt that attaches is to the camshaft.

Offline calj737

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Re: CB650 Custom Rust Bucket
« Reply #14 on: August 19, 2018, 12:06:58 PM »
Remove the stator cover (left side). Theres a 14mm hex head bolt. Put a breaker bar on it. Motor in neutral. A LONG breaker bar... Have a mate hold the bike really well.

BEFORE YOU DO THIS: Check the oil pan. Has any of the ATF/Acetone mixture seeped past the pistons yet? If not, you need to wait longer. I spent months soaking an engine off and on.

Another option is to cut the cam chain since you'll probably be doing an engine tear down anyway. Remove the head. You now have direct access to the piston tops. Fill the cylinders with kerosene and light them up. The heat directly on the cylinders will allow a breaker bar to rotate the motor. I refer to it as an SOHC BBQ!  :)
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Offline RAFster122s

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Re: CB650 Custom Rust Bucket
« Reply #15 on: August 19, 2018, 01:01:11 PM »
Well the good news is you can use 750 round top carbs on your bike. Send a PM to Bill or David Benton for a price on a replacement set.
I thought the 750 carbs were only usable on the non CV carbs.


With main jet carb post eroded you are going to have to replace the carbs if the jet will not seal, but with that much crap in the bowl you are guaranteed to have all the fine ports clogged with that crap. That white stuff laughs at carb cleaner like it was water. If they could come clean it would have to be with hours of industrial ultrasonic cleaner with something that could dissolve the white stuff. The CVs are simply too sensitive to being clean I am gonna say it really would not be worth it. Salvage other parts that could be usable and screws in good shape as well as the brass jets. The domes can be polished up nice after sanding that oxidized layer and any clear coat off.  The bike looks like it was left with ethanol fuel in it with it being sitting outside in a area rich with sea water nearby or ridden in winter with salt on the roads.

David- back in the desert SW!

Offline CarbonK

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Re: CB650 Custom Rust Bucket
« Reply #16 on: August 19, 2018, 02:18:24 PM »
Remove the stator cover (left side). Theres a 14mm hex head bolt. Put a breaker bar on it. Motor in neutral. A LONG breaker bar... Have a mate hold the bike really well.

BEFORE YOU DO THIS: Check the oil pan. Has any of the ATF/Acetone mixture seeped past the pistons yet? If not, you need to wait longer. I spent months soaking an engine off and on.

Another option is to cut the cam chain since you'll probably be doing an engine tear down anyway. Remove the head. You now have direct access to the piston tops. Fill the cylinders with kerosene and light them up. The heat directly on the cylinders will allow a breaker bar to rotate the motor. I refer to it as an SOHC BBQ!  :)

Damn, months? Doesn’t look like the mixture made it past the pistons. Maybe I’m just not being patient enough. No danger of stripping the threads on that 14mm bolt?

The bike looks like it was left with ethanol fuel in it with it being sitting outside in a area rich with sea water nearby or ridden in winter with salt on the roads.

Yeah I think someone might have used it as an anchor at one point.

Offline calj737

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Re: CB650 Custom Rust Bucket
« Reply #17 on: August 19, 2018, 02:26:23 PM »
Cut the chain, pull the head. Time to get medieval on it.
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Offline CarbonK

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Re: CB650 Custom Rust Bucket
« Reply #18 on: August 30, 2018, 08:22:01 AM »
Got impatient and split the chain. Put the 650 cam into my 550 for now. Gonna take the head off today and have a BBQ.

Offline CBJoe

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Re: CB650 Custom Rust Bucket
« Reply #19 on: August 30, 2018, 10:32:18 AM »
Got impatient and split the chain. Put the 650 cam into my 550 for now. Gonna take the head off today and have a BBQ.

Dont forget the video  ;D
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Offline CarbonK

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Re: CB650 Custom Rust Bucket
« Reply #20 on: August 30, 2018, 12:21:25 PM »
Got impatient and split the chain. Put the 650 cam into my 550 for now. Gonna take the head off today and have a BBQ.

Dont forget the video  ;D

If I’m ever able to get the head off, I got you. Looks like I got a stripped cylinder head bolt. Not really sure what to do now.
« Last Edit: August 30, 2018, 12:34:19 PM by CarbonK »

Offline CarbonK

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Re: CB650 Custom Rust Bucket
« Reply #21 on: August 30, 2018, 12:38:33 PM »
Scratch that, false alarm. Just a big layer of dirt that prevented a socket from seating lol.

Offline CarbonK

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Re: CB650 Custom Rust Bucket
« Reply #22 on: August 30, 2018, 02:19:25 PM »
Sucked up all the ATF/Mystery Oil mix and found rust and dirt, not sure what I expected. Heated the cyilinders up with a MAP torch and used a wooden dowel and hammer to bang on them but they didn’t budge. Time to get some kerosene.

Offline calj737

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Re: CB650 Custom Rust Bucket
« Reply #23 on: August 30, 2018, 04:52:41 PM »
Dont bang on the pistons you'll only damage the rods.

Remove the alternator cover (left side). 6 point socket on the 14mm bolt, long breaker bar. Have someone hold the bike, then budge the bar. You can fill the chambers with Kerosene and light them up a few times. Pour some MMO in while they're hot. Then the breaker bar. She will come loose-
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Offline algophobe

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Re: CB650 Custom Rust Bucket
« Reply #24 on: August 30, 2018, 06:42:10 PM »
gotta get my popcorn and soda. great lessons to be learned here.
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