Topic: 1982 CB650SC Build

[Hutch]

Posting my progress to date, it's running reasonably well.  My plan is to finish a few odds and ends over the winter, and ride in rat bike mode next season before breaking down for body work and paint.

When I got it the bike was barely running, but had a lot of electrical issues from the PO.  I had to redo much of the wiring eliminating poorly done splices and a melted connector. 

[Hutch]

One of my first orders of business was to find a tank for both aesthetic reasons and to eliminate the vacuum assisted petcock.  I settled on a tank from a 1980 CB650 that required relocation of the the front tank mount.  The engine was out of the frame at the time luckily the petcock cleared the carbs at final assembly.  It was damn close.

I also fabricated an adapter to mount a single large K&N pod to the plenum.  I had to eliminate the air cleaner box so that I can have space to relocated the battery.  I was able to mount all of the electrical components to the frame or the bottom of the seat pan.

[Hutch]

New gauges, headlight, turn signals, bar end mirrors, changed the choke to a plunger style and relocated below the tank.  Also eliminated the brake bridge in favor of two SS brake lines directly from the MC to the calipers.  Also filled the holes where the fork air assist tube attaches to the top caps since the air assist is worthless.

[Hutch]

Made a seat pan from 16 gauge mild steel following the counters of the frame.  I was set on not adding a hoop and considered a single seat using the original rear frame bridge to mount a rear cowl.  Ultimately the desire for a two rider seat trumped that idea.  I plan to make a seat pad from yoga mat layer with a descent quality softer foam on top.  The cover will be brown leather with horizontal stitching.  I'll leave the cover to the pros, there's a local shop that makes custom seat covers.  I also added some side covers to hide the wiring and electrical bits.

[Hutch]

Next up, wiring aftermarket right and left switches to clean up the cockpit along with a new throttle.  New GP style pegs.  The frame and most components as well as the wheels will be paint black with rustoleum appliance epoxy.  The tank will be white with a vertical red strip through the gas cap along with a thinner red strip directly behind.  I plan to us the original tank badges either polished up or painted black.  I want to keep the patina for the motor, I scotch brite the few shiny bits.  I'm also leaning towards keeping the exhaust as is with a very light polish, or pain the pipes black, and scotch brite the mufflers.

Also have to work out the indicator lights.  Neutral only lights if I try to start the bike in gear.  The oil pressure light does not light at all. 

[Hutch]

Had the seat covered by a local shop, they did a great job.  Still have to sort out the new switch wiring, and break down for paint.

[kerryb]

That's a comfy looking seat.  What material did your upholsterer use?
One other question... do you have any run time on the new air intake?  Does it work as well as stock airbox?

Keep at it, looks like you'll be done soon.

[Hutch]

The pad is a high quality half inch yoga mat tripled-up using 3M Super 77 Spray Adhesive plus another half inch of softer foam on top stitched to the cover. The yoga mat was hard to shape. While it feels great, I would look into a carpet pad or other foam that can be easily shaped with a knife and foam shaver. I drilled out the pan spacing the holes 1" apart for riveting the leather cover.  I had a shop make the leather cover from some leather that I had.  I'm not sure of the weight.  They also covered the bottom with a thin felt to finish.

I don't have an m unit or place to hide an electronics tray, so everything is mounted to the bottom of the seat pan or frame.  I used rubber cushioned cable clamps to secure the harness across the bottom of the seat pan. 

I have about 50 miles on it so far, but nothing at WOT for an extended time.  So far so good with this set up, with the possible exception of running slightly leaner which required nothing more than a mixture screw adjustment.  K&N RC-8100 Universal Clamp-On Air Filter.

[kerryb]

The pad is a high quality half inch yoga mat tripled-up using 3M Super 77 Spray Adhesive plus another half inch of softer foam on top stitched to the cover. The yoga mat was hard to shape. While it feels great, I would look into a carpet pad or other foam that can be easily shaped with a knife and foam shaver.

That's very interesting,  I guess I better experiment with shaping  yoga foam.  That was my plan of foam to use.  I still have time to find a replacement if needed.  Bike looks good , are those stock length shocks?

[Hutch]

I couldn't finding anything online on how to shape neoprene.  An electrical knife worked well for cutting the neoprene to the shape of the pan.  I tried an orbital sander and angle grind with no luck, so I used a sharp knife to cut to a rough shape.  The 1/2 pad stitched to the leather cover took care of any imperfections.  It's a trade-off... the yoga mat is very comfortable and you don't have to worry about it getting wet.  Also, much cheaper than most other foam options when I checked the online retailers due to shipping costs.  Born Motors has a great video on shaping a seat from bonded urethane foam (i.e. carpet pad).  In hind sight, I would have gone with 2 layers of yoga mat, and 1 or 2 layers if carpet pad to shape.  Its my understanding that using multiple types of padding, with softer/less dense as the top layer is optimal.

Shocks a longer than stock at 14.5" and the from is dropped about 2" so that I could mount the clip-ons above the top yoke.  It had a cruiser stance to begin with, so this had no negative effect on the handling.  I haven't measured rake and trail, but it's stable and turns easy at any speed, however, I can feel the difference at very low speeds (<10mph). 

[kerryb]

Just bumping this thread so all three could be together for a moment

[odioanonimo]

haha the project shop certainly makes the 82 cb650sc seem much more popular than i think it actually is!

[Hutch]

haha the project shop certainly makes the '82 cb650sc seem much more popular than i think it actually is!

Well with the 750's and other CB's getting much harder to find, and fetching top dollar the 650's are a bargain.  Depending on the year, I believe they produce more HP at the crank the the 750.  They are a fine platform IMO, and kerryb provided the ultimate "how to" to convert the frame for a traditional cafe look with a straight boneline and hoop.  So many people have shied away from the 650 for aesthetic reasons withe the s in the frame, and cruiser stance with the 16" rear, 19" front wheel.  Maybe we'll see more conversion parts going forward.  Would like to see hubs to fit 18" front and rear wheels. 

Next up for me, besides aftermarket switches, will be to properly lower the front forks by adding a spacer and cutting the springs.  If it doesn't work out, I can always find replacement springs, or upgrade to Progressive springs. 

[SOHC4 Cafe Racer Fan]

haha the project shop certainly makes the '82 cb650sc seem much more popular than i think it actually is!

Well with the 750's and other CB's getting much harder to find, and fetching top dollar the 650's are a bargain.  Depending on the year, I believe they produce more HP at the crank the the 750.  They are a fine platform IMO, and kerryb provided the ultimate "how to" to convert the frame for a traditional cafe look with a straight boneline and hoop.  So many people have shied away from the 650 for aesthetic reasons withe the s in the frame, and cruiser stance with the 16" rear, 19" front wheel.  Maybe we'll see more conversion parts going forward.  Would like to see hubs to fit 18" front and rear wheels. 

Next up for me, besides aftermarket switches, will be to properly lower the front forks by adding a spacer and cutting the springs.  If it doesn't work out, I can always find replacement springs, or upgrade to Progressive springs.

The 1979 is a great model but not plentiful. It has identical geometry to the 550, and the 79-80 heads match up to 750 carburetors.

[Hutch]

Replaced the OEM pegs and mounting brackets with something much cleaner. Dropped the foot position about two and a half inches down and 2 inches back.  A much more comfortable riding position.  Also replaced the stock shifter arm with a shorter one that allows for more clearance and easier shifting.

Much better than the stock pegs and brackets.

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