Author Topic: 1981 CB650C Cafe project bike.  (Read 1874 times)

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Offline Hotwheelbill

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1981 CB650C Cafe project bike.
« on: March 13, 2015, 02:16:14 PM »
I picked this up for $500 from a co worker that could not get the carbs right. I hope to find some '82 carbs. Will '82 carbs from a 650 Nighthawk?
And I picked up a cb750 tank for it.

I love to make my bikes worthless due to high mileage!
2004 ST1300A .... the fast one. And dragging pegs on a CT.
1972…parts bike
1974…. Rusty frame but runs
1974 CB750..... Powder coated frame and parts, waiting for $$ hot rod motor.
1972 with 1975 old school drag motor

Offline scunny

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Re: 1981 CB650C Cafe project bike.
« Reply #1 on: March 13, 2015, 02:26:41 PM »
as long as they are the cv carbs(round tops), 79 and 80 had mechanical carbs and a different head.
past-cb100,ts250,cb500,cb500,gs1000,gs650g.phillips traveller
present-CB 650 retro
            VTR1000F3
           XL250S riverbed rocket
           TS250[sold]
           TS185[sold]
           XL125S[sold]
           MT50 (white)
           MT50 (red)[sold]
           KN250/XS400 project
           XR/XL250 bitsa under construction
           SL100[sold]
           XL250R
           pedal(pub bike) leaks oil
my gallery http://gallery.sohc4.net/members/personal/scunny

Offline SOHC4 Cafe Racer Fan

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Re: 1981 CB650C Cafe project bike.
« Reply #2 on: March 13, 2015, 02:29:32 PM »
I just did a tear-down on my 1982 CB650C.  I'm having James (Harisuluv) rebuild the carburetors as a trade for a Lester wheel.
1975 CB550K1 "Blue" Stockish Restomod (http://forums.sohc4.net/index.php?topic=135005.0)
1975 CB550F1 frame/CB650 engine hybrid "The Hot Mess" (http://forums.sohc4.net/index.php/topic,150220.0.html)
2008 Triumph Thruxton (http://forums.sohc4.net/index.php/topic,190956.0.html)
2014 MV Agusta Brutale Dragster 800
2015 Yamaha FZ-09 (http://forums.sohc4.net/index.php/topic,186861.0.html)

"There are some things nobody needs in this world, and a bright-red, hunch-back, warp-speed 900cc cafe racer is one of them — but I want one anyway, and on some days I actually believe I need one.... Being shot out of a cannon will always be better than being squeezed out of a tube. That is why God made fast motorcycles, Bubba." Hunter S. Thompson, Song of the Sausage Creature, Cycle World, March 1995.  (http://www.latexnet.org/~csmith/sausage.html and https://magazine.cycleworld.com/article/1995/3/1/song-of-the-sausage-creature)

Sold/Emeritus
1973 CB750K2 "Bionic Mongrel" (http://forums.sohc4.net/index.php?topic=132734.0) - Sold
1977 CB750K7 "Nine Lives" Restomod (http://forums.sohc4.net/index.php?topic=50490.0) - Sold
2005 RVT1000RR RC51-SP2 "El Diablo" - Sold
2016+ Triumph Thruxton 1200 R (http://forums.sohc4.net/index.php/topic,170198.0.html) - Sold

Offline rb550four

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Re: 1981 CB650C Cafe project bike.
« Reply #3 on: March 13, 2015, 03:11:52 PM »
I know a 550 tank won't work without customizing  a seat and a tank mount, haven't tried a 750 tank on a 650, what's the plan ? How will you get this to work? and what is the look that you're going for? Just wondering.
 I'm not wild about an angled tank and seat that is '80-82 650, I like the classic straight lines of the 500/550/750 or 79 650 and have found it easier to obtain this classic look on a classic 550 frame ,over cutting the 650 frame.
 Do you know something that I don't know?  I'd like to know of another way that would work
(if that's what you're doing).
A few Honda 500's, a few Honda 550's, a few Honda 650's, '72 cb 450, a couple 500/550/650 hybrids, and 2001 750. 
  550 Snowbike -Somebody had to do it.
  http://forums.sohc4.net/index.php/topic,101678.0.html             
http://forums.sohc4.net/index.php/topic,137317.msg1550907.html#msg1550907

Offline SOHC4 Cafe Racer Fan

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Re: 1981 CB650C Cafe project bike.
« Reply #4 on: March 13, 2015, 04:25:40 PM »
I know a 550 tank won't work without customizing  a seat and a tank mount, haven't tried a 750 tank on a 650, what's the plan ? How will you get this to work? and what is the look that you're going for? Just wondering.
 I'm not wild about an angled tank and seat that is '80-82 650, I like the classic straight lines of the 500/550/750 or 79 650 and have found it easier to obtain this classic look on a classic 550 frame ,over cutting the 650 frame.
 Do you know something that I don't know?  I'd like to know of another way that would work
(if that's what you're doing).

I have to agree with rb550four as to the aesthetics of the 80-82 650 frames -- I own one.  I think Honda was definitely going for a cruiser design.  It almost feels like a soft tail chopper.  The 550 tank will not work.  I don't know about the 750 either.  you may need to cut the bottom off the tank and fabricate your own tunnel and mounts.

I suppose it depends on what design and function you want to achieve.  If it's a chopper, cruiser, bobber, that frame will work fine.  If you want something more like a tracker, café, etc. you may want to do some frame alternations to the rear top rails.  For me, I am scavenging the motor for possible later use (right now the motor is in mothballs in my storage space) and I may save the frame for some crazy project in the future (since it is titled).

That said, the CX500 plastic maggot has the same frame dip (where the seat is) and plenty of people have turned them into nice looking (but slow) rides.
1975 CB550K1 "Blue" Stockish Restomod (http://forums.sohc4.net/index.php?topic=135005.0)
1975 CB550F1 frame/CB650 engine hybrid "The Hot Mess" (http://forums.sohc4.net/index.php/topic,150220.0.html)
2008 Triumph Thruxton (http://forums.sohc4.net/index.php/topic,190956.0.html)
2014 MV Agusta Brutale Dragster 800
2015 Yamaha FZ-09 (http://forums.sohc4.net/index.php/topic,186861.0.html)

"There are some things nobody needs in this world, and a bright-red, hunch-back, warp-speed 900cc cafe racer is one of them — but I want one anyway, and on some days I actually believe I need one.... Being shot out of a cannon will always be better than being squeezed out of a tube. That is why God made fast motorcycles, Bubba." Hunter S. Thompson, Song of the Sausage Creature, Cycle World, March 1995.  (http://www.latexnet.org/~csmith/sausage.html and https://magazine.cycleworld.com/article/1995/3/1/song-of-the-sausage-creature)

Sold/Emeritus
1973 CB750K2 "Bionic Mongrel" (http://forums.sohc4.net/index.php?topic=132734.0) - Sold
1977 CB750K7 "Nine Lives" Restomod (http://forums.sohc4.net/index.php?topic=50490.0) - Sold
2005 RVT1000RR RC51-SP2 "El Diablo" - Sold
2016+ Triumph Thruxton 1200 R (http://forums.sohc4.net/index.php/topic,170198.0.html) - Sold

Offline Hotwheelbill

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Re: 1981 CB650C Cafe project bike.
« Reply #5 on: March 13, 2015, 07:22:18 PM »
I have some ideas of ...hiding .....the dip in the frame and using a fiberglass seat of some kind. This is my first build. Only a parts changer in the past. I have a look in my head, but don't have any idea how to get there, or tell it for that matter.
I love to make my bikes worthless due to high mileage!
2004 ST1300A .... the fast one. And dragging pegs on a CT.
1972…parts bike
1974…. Rusty frame but runs
1974 CB750..... Powder coated frame and parts, waiting for $$ hot rod motor.
1972 with 1975 old school drag motor

Offline Hotwheelbill

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Re: 1981 CB650C Cafe project bike.
« Reply #6 on: March 13, 2015, 07:24:46 PM »
I have read that a pre 1976 CB750 tank will work with a rubber gromitt change. Not sure, but the tank was cheap enough to find out.
I love to make my bikes worthless due to high mileage!
2004 ST1300A .... the fast one. And dragging pegs on a CT.
1972…parts bike
1974…. Rusty frame but runs
1974 CB750..... Powder coated frame and parts, waiting for $$ hot rod motor.
1972 with 1975 old school drag motor

Offline scunny

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Re: 1981 CB650C Cafe project bike.
« Reply #7 on: March 14, 2015, 02:28:17 AM »
you have cv carbs(round tops) what makes you think that new carbs are needed ?
past-cb100,ts250,cb500,cb500,gs1000,gs650g.phillips traveller
present-CB 650 retro
            VTR1000F3
           XL250S riverbed rocket
           TS250[sold]
           TS185[sold]
           XL125S[sold]
           MT50 (white)
           MT50 (red)[sold]
           KN250/XS400 project
           XR/XL250 bitsa under construction
           SL100[sold]
           XL250R
           pedal(pub bike) leaks oil
my gallery http://gallery.sohc4.net/members/personal/scunny

Offline Hotwheelbill

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Re: 1981 CB650C Cafe project bike.
« Reply #8 on: March 14, 2015, 02:33:39 AM »
I have read that the 1981 , only, had pressed in low jets that can not be changed and hard to clean. It makes it hard to tune if you remove the stock air box. I do not want the look of the air box. '80 carbs will work with a head change. '82 will work without any change and have screw in low jets.
I love to make my bikes worthless due to high mileage!
2004 ST1300A .... the fast one. And dragging pegs on a CT.
1972…parts bike
1974…. Rusty frame but runs
1974 CB750..... Powder coated frame and parts, waiting for $$ hot rod motor.
1972 with 1975 old school drag motor

Offline SOHC4 Cafe Racer Fan

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Re: 1981 CB650C Cafe project bike.
« Reply #9 on: March 14, 2015, 09:52:01 AM »
I wasn't aware of this idiosyncrasy with 81 carburetors.  If so, I'm glad I have the 82s.
1975 CB550K1 "Blue" Stockish Restomod (http://forums.sohc4.net/index.php?topic=135005.0)
1975 CB550F1 frame/CB650 engine hybrid "The Hot Mess" (http://forums.sohc4.net/index.php/topic,150220.0.html)
2008 Triumph Thruxton (http://forums.sohc4.net/index.php/topic,190956.0.html)
2014 MV Agusta Brutale Dragster 800
2015 Yamaha FZ-09 (http://forums.sohc4.net/index.php/topic,186861.0.html)

"There are some things nobody needs in this world, and a bright-red, hunch-back, warp-speed 900cc cafe racer is one of them — but I want one anyway, and on some days I actually believe I need one.... Being shot out of a cannon will always be better than being squeezed out of a tube. That is why God made fast motorcycles, Bubba." Hunter S. Thompson, Song of the Sausage Creature, Cycle World, March 1995.  (http://www.latexnet.org/~csmith/sausage.html and https://magazine.cycleworld.com/article/1995/3/1/song-of-the-sausage-creature)

Sold/Emeritus
1973 CB750K2 "Bionic Mongrel" (http://forums.sohc4.net/index.php?topic=132734.0) - Sold
1977 CB750K7 "Nine Lives" Restomod (http://forums.sohc4.net/index.php?topic=50490.0) - Sold
2005 RVT1000RR RC51-SP2 "El Diablo" - Sold
2016+ Triumph Thruxton 1200 R (http://forums.sohc4.net/index.php/topic,170198.0.html) - Sold

Offline Hotwheelbill

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Re: 1981 CB650C Cafe project bike.
« Reply #10 on: March 15, 2015, 08:54:44 AM »
I was able to spend an hour or so on the bike yesterday. Pulled SOME of the stuff that will not be going back on. And I am sure I found the problem with the carbs. '82 carbs on the way.
I love to make my bikes worthless due to high mileage!
2004 ST1300A .... the fast one. And dragging pegs on a CT.
1972…parts bike
1974…. Rusty frame but runs
1974 CB750..... Powder coated frame and parts, waiting for $$ hot rod motor.
1972 with 1975 old school drag motor

Offline Hotwheelbill

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Re: 1981 CB650C Cafe project bike.
« Reply #11 on: March 16, 2015, 04:24:06 PM »
Well, my SOHC CB750 tank came today and it fit like a glove. Smaller gromits would be better, but it fit with a little pushing. I will shave a little of mine and be done with that part. I will need to mod the back of the tank or bike to bolt it down.
LOL, My postal woman was soooo happy to get this tank out of her truck! The smell........holy crap , the smell...
I love to make my bikes worthless due to high mileage!
2004 ST1300A .... the fast one. And dragging pegs on a CT.
1972…parts bike
1974…. Rusty frame but runs
1974 CB750..... Powder coated frame and parts, waiting for $$ hot rod motor.
1972 with 1975 old school drag motor

Offline Hotwheelbill

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Re: 1981 CB650C Cafe project bike.
« Reply #12 on: March 16, 2015, 04:39:57 PM »
OK, a shot to explain what I want out of this bike. I am looking to do a Cafe bike. I know that the bike runs well and after the carb fix, it will be reliable. To change the form or the "C" of the CB650, I plan to use a Cafe fiberglass straight form seat and use a Stainless Steal Mesh (looking for something different) for the side cover areas and bring it up to cover the "dip" in the frame.
I love to make my bikes worthless due to high mileage!
2004 ST1300A .... the fast one. And dragging pegs on a CT.
1972…parts bike
1974…. Rusty frame but runs
1974 CB750..... Powder coated frame and parts, waiting for $$ hot rod motor.
1972 with 1975 old school drag motor

Offline SOHC4 Cafe Racer Fan

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Re: 1981 CB650C Cafe project bike.
« Reply #13 on: March 16, 2015, 04:55:26 PM »
Can you post a photo of how the tank mocks up on the 650 frame?
1975 CB550K1 "Blue" Stockish Restomod (http://forums.sohc4.net/index.php?topic=135005.0)
1975 CB550F1 frame/CB650 engine hybrid "The Hot Mess" (http://forums.sohc4.net/index.php/topic,150220.0.html)
2008 Triumph Thruxton (http://forums.sohc4.net/index.php/topic,190956.0.html)
2014 MV Agusta Brutale Dragster 800
2015 Yamaha FZ-09 (http://forums.sohc4.net/index.php/topic,186861.0.html)

"There are some things nobody needs in this world, and a bright-red, hunch-back, warp-speed 900cc cafe racer is one of them — but I want one anyway, and on some days I actually believe I need one.... Being shot out of a cannon will always be better than being squeezed out of a tube. That is why God made fast motorcycles, Bubba." Hunter S. Thompson, Song of the Sausage Creature, Cycle World, March 1995.  (http://www.latexnet.org/~csmith/sausage.html and https://magazine.cycleworld.com/article/1995/3/1/song-of-the-sausage-creature)

Sold/Emeritus
1973 CB750K2 "Bionic Mongrel" (http://forums.sohc4.net/index.php?topic=132734.0) - Sold
1977 CB750K7 "Nine Lives" Restomod (http://forums.sohc4.net/index.php?topic=50490.0) - Sold
2005 RVT1000RR RC51-SP2 "El Diablo" - Sold
2016+ Triumph Thruxton 1200 R (http://forums.sohc4.net/index.php/topic,170198.0.html) - Sold

Offline Hotwheelbill

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Re: 1981 CB650C Cafe project bike.
« Reply #14 on: March 17, 2015, 05:19:35 AM »
Now off to the radiator shop.
I love to make my bikes worthless due to high mileage!
2004 ST1300A .... the fast one. And dragging pegs on a CT.
1972…parts bike
1974…. Rusty frame but runs
1974 CB750..... Powder coated frame and parts, waiting for $$ hot rod motor.
1972 with 1975 old school drag motor

Offline mrfish2

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Re: 1981 CB650C Cafe project bike.
« Reply #15 on: March 19, 2015, 08:08:08 AM »
That bike will look pretty sweet when you're done, I'm surprised that tank fit so well. If you ever need any extra parts I might still have some things off of an 82 nighthawk, frame too.
1976 CB550K            1979 XS1100
1980 CB650C - Sold

It's a little motor and likes having the tits revved off it.

Offline Hotwheelbill

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Re: 1981 CB650C Cafe project bike.
« Reply #16 on: March 19, 2015, 10:40:26 AM »
Thank you for the offer, I will keep that in mind. I should have the carbs in today and then I need to order an O ring and gasket kits and I think a stage 2 jet kits.
Just looking at pics of an '82 Nighthawk and I like the tail section. Has anyone tried to use this section in  a build? Like from the shock section back.
« Last Edit: March 19, 2015, 10:45:32 AM by Hotwheelbill »
I love to make my bikes worthless due to high mileage!
2004 ST1300A .... the fast one. And dragging pegs on a CT.
1972…parts bike
1974…. Rusty frame but runs
1974 CB750..... Powder coated frame and parts, waiting for $$ hot rod motor.
1972 with 1975 old school drag motor

Offline Hotwheelbill

  • Hot Shot
  • ***
  • Posts: 283
I love to make my bikes worthless due to high mileage!
2004 ST1300A .... the fast one. And dragging pegs on a CT.
1972…parts bike
1974…. Rusty frame but runs
1974 CB750..... Powder coated frame and parts, waiting for $$ hot rod motor.
1972 with 1975 old school drag motor