Author Topic: We didn't start the fire! Space's CB750K4 Resurrection!  (Read 1088 times)

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Offline adams_in_space

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We didn't start the fire! Space's CB750K4 Resurrection!
« on: December 31, 2015, 03:26:07 pm »
I was having issues with my VS700 Bobber. She was running a bit rich...





Needless to say, it was a bad day.
I got my hands on a fairly complete CB750 a few months prior, so I quickly set to work. The bike had changed hands a few times and ended up at a local shop for a build. The project fell through and the owner abandoned it. Three years later my older brother rescued it from a swap meet for $150 and in a stroke of charity, gifted to me to ease the loss of my Suzuki.



My initial intentions were to keep her stock. I just wanted to freshen up some rough spots and get on the road. I knew the carbs were junk, there were a few minor wiring issues, barttery, tires, brakes; the majority of items looking to be ignored maintenance.



Rebuilding the gummed up carbs looked to be the same cost as purchasing a rebuilt set from a local wrencher, lovingly knows as " CB Jim". I found him at a swap meet in spring and bought a fully set-up and bench balanced carb set for a couple hundred bucks and installed, mkaing the necessary repairs to get her fired up. But like any girly who's been rode hard and put away wet, there are more than just self esteem issues underneath.



After a no-power situation I decided to peel back the harness loom and have a look. I found the entire grounding system was fried from the stem back. I also noted way more degradation from time and exposure than initially accounted for. At this point it was clear that the bike was going to need a full tear-down before it moved again. It was already in my buddies shop and on the bench, way waste time?



So began what became the discovery phase. Setting out to fix one issue meant stumbling across two more in the process. All the hardware was removed down to frame and motor, taking note of conditions. Most obvious items were neck bearings, head light, brakes, tires, chain.



Originally I wanted to retain all the factory elements. Full controls and displays, turn signals, fender, but looking at the quality of the items in my possession hinted that I was about to go the cliche cafe direction. The accessories were all removed, a new wire harness was built from the ground up (neck back?), items ordered.



While replacing the cables I came across a few issues with the hand controls, which were confirmed once the wiring was complete. The controls were mainly junk, but new ones were not exactly in the budget. This further enforced my "cafe" ideals and the hand controls were all but by-passed, reducing the amount of front end wiring to the essentials: headlight and key switch.



Brakes were another issue all together. The caliper was seized beyond repair and a new one was sourced locally. This was installed along with a new stainless piston, seals, and lines.





I had new Avon RoadRiders installed along with new wheel bearings. The swing arm, brake stay, and exhaust were all cleaned, painted, and finished matte black.



DIY shot glasses. Necessity.


Stock bars were removed in favor of 10* clip-ons. New clutch cable. New headlight bucket. New light (non-fixed). Polished the top tree.

She fired up for the first time in years and run with only a few pops and sputters now and then. A bit of grounding work cleaned most of that up, but suddenly and unexpectedly, she shut off. All wiring was double check, repairs were made and needed, though there were intermittent issues with ignition signal. I was having a charging issues as well, and opted for a modified DOHC reg/rec combo to try and solve the problems. In reading I was made aware of the risk to the battery, due to the field coil reversal necessary to make the regulator excite the stator. It was a temporary fix which I still have yet to completely rectify.



Having completed most of the labor intensive work at the shop, I decided to ride her home and address any electric issues at a later date. I eventually ended buying another battery due to electrical discharge from using the wrong regulator. I purchased and installed a Ricks combo reg/rec, a DynaS ignition, and went back to work.



Long story short on the charging system, it has all been replaced save for the magneto/rotor, and it still will not charge the battery. Frustrated doesn't describe the scenario. So, I turned to art therapy in order to keep from committing societal atrocities. The tank was removed, stripped, cleaned, imperfections identified like a plastic surgery patient, boned, primed, and painted.



I was feeling nautical and went with a hand-lain stripe, off white primary and a muted blue secondary.





I went on a ride thinking I had solved the issues and took a few snaps. The trailer ride home reminded me that I had indeed not solved the issues :/



The stable.



Offline seanbarney41

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Re: We didn't start the fire! Space's CB750K4 Resurrection!
« Reply #1 on: December 31, 2015, 04:21:14 pm »
This is a good story so far. :)
If it works good, it looks good...

DH

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Re: We didn't start the fire! Space's CB750K4 Resurrection!
« Reply #2 on: December 31, 2015, 10:10:56 pm »
In St. Louis?.Sorry about your old bike. Fire is bad enough, but that spot on hwy.40 is scary, especially for a break down.
Good luck with the 750..
« Last Edit: December 31, 2015, 10:20:49 pm by DH »

Offline SOHC4 Cafe Racer Fan

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Re: We didn't start the fire! Space's CB750K4 Resurrection!
« Reply #3 on: January 01, 2016, 09:50:35 am »
Yeah, that break-down and FIRE looked positively NO BUENO. 

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