Topic: CB750K3 project: Burning Spear

[NagChampa]

Picked up a 1973 CB750 for less than scrap prices a little while ago. It had been ridden hard and left for dead in storage, then moved to a backyard where I found it. Definitely will have to put some work into this before it will become road worthy.

This is my first project as well as my first bike. Yes I know that most barnfinds cost over a grand to get started. I am actually more interested in building and learning about this machine than riding it right now. There will be time to ride in the future but will probably have another project by then. Hopefully with help from the fine folks of SOHC4forums and the Honda service manual, I will have this kitten purring in time.

There are a few issues that have to be dealt with, my short term goal is to get it running, ride it for a season, take it apart for a shave, paint and polish, put it back together again and enjoy.





As I brought it home. First thing to go would be the sissy bar. Paint will not be so purple in the future as well.



4 in 1 header pipes are crudely cut off just past the collectors. They are also pounded flat on the bottom. Not sure if they are worth saving, probably just keep them for welding practice in the future. Definitely going on the 'Maybe' pile for now.



I had to take a before photo



Few days later




Some of the wiring was held in place with string



This is why I am going with new wiring, that and the liberal use of red automotive wire with hand twisted and electrical taped connectors.



Had to drill off the handle bar switch gear on both sides.





Left over damage from previous side car conversion. Looking at right side passenger peg triangle. I debated restoring this frame to stock specs but will likely cut off these triangles in the future for a cleaner look.





Now this is what you call a booger assed weld job. I don't know what to say but the weld should probably be fused to something



Clip for front fender support is broken. Anybody know if these are still available?



Found a spare motor on kijiji, the motor in the bike had a hole in front of the sprocket. Will get this one running in the bike and will have a machine shop weld up the original case. Original motor will be rebuilt or sold/bartered for parts.



Pistons on spare motor look like they should.







Bores look good, will just give a quick hone



Will take these apart and try to get everything blasted clean.

That is all I have for today, have to borrow some tools from my brother to remove valves this week.

[NagChampa]

Thank you for the words of encouragement Vincent.

Bought an impact screwdriver on the weekend, worked great on freeing up the screws on the clutch case including one that was badly stripped. It was almost round, loaded the robertson head in the impact, gave it a few taps with a hammer and out it came. Not so lucky with one exhaust flange. Well the exhaust flange is ok but I bent the phillips head screwdriver bit. Looks like soft serve ice cream, sorta.
 

What I started with



Chewed up wiring harness, this thing was hacked apart so much, lets me know why it was not being ridden, that and the hole in the crankcase.



Where I am now. If I can trick a couple of people into helping me remove the motor, I would be in an even better place. Still waiting for my brother to bring his motorcycle jack here, do not have a center stand. Do not want to lay the frame down to remove the engine because the sidecar mounts do not allow the frame to get close enough to touch the ground. Do not want to risk damaging this motor more than it is already.  Want to remove the forks and strip the frame bare.

Hope to get more pictures up soon, have to clean up my workspace.

Also would like to pull the valves soon and try to get some work done on my engine cases(both sets need welding/machine work)

[goldarrow]

you can drain oil out of the motor, remove oil filter.  loosen all the engine hanger bolts, lay the bike on its ride side, use plenty of blankets as cushions, then remove all engine hanger bolts, left engine out.  one man show.   

[NagChampa]

That is the direction I am heading in goldarrow. Taking too long to rustle up any help.

Really happy that you chimed in here, have read your Spyder thread a couple of times now, very inspiring.

[Nic]

As for the side car mounts, I would NOT cut off the whole triangle but rather cut the mounts off, angle grind the crap off the tubes and fill with brass, file smooth and keep the stock look. Pretty easy to do and you might need the triangle to mount your NEW exhaust. Forget lifting that motor out too, just lay it over n lift off the frame.
I bought a basket case K2 for not much, I'm up to 7 grand so far but I have gone the full falcon though, there nothing cheap about a cheap bike. Will be interesting to see how much you end up spending, you say you just wanna get it running but as you go along you just keep finding money pits all over the place, it was impossible for me to ignore them hence the 7 grand, almost done now n the thing will look the biz and I'll know the state of everything, er, like, brand new. You'll need lots of new rubber bits on that thing, them alone will shock you price wise.

[bjatwood]

I learned the hard way back in the early eighties when I bought a 70 1/2 Z/28. I could have bought a perfect one for 9,500 bucks. But NO I had to buy a "project" car for 2,500. Well 3 years later and 10 grand it was perfect. So I spent 12,500 for my 9,500 dollar car, but the lessons learned along the way were priceless. I sold the car in the Muscle car $$ heydays of the early 90's for much more, and used the money for a downpayment on a house on the lake. Ended up flipping the house for a cool 85,000 dollar profit 6 years later. 
Moral of the story, build it right regardless of cost, you will never lose any money on it. And if you do, you sold it to early....
Sorry for the thread jack....

[NagChampa]

Nic, that is exactly how I removed the motor today. Was easier than I had expected to boot.

I just want to get it running and safe enough to ride at first. Will disassemble the motor completely, have everything cleaned, inspected, blasted, painted, reassembled. The frame will go through the same treatment and likely be powdercoated.

I expect to take a while to put this one back together as I would like to take my time aquiring parts and waiting for things to be painted, plated, polished.

You are correct about the money pit traps, they are all over the place. To be honest, I would be quite content spending 7 grand on this project if that is what it takes for me to get it done the way I want. Did not expect a cheap project but could not pass up this bike for the price. Anything I replace from this point will be brand new if possible. My build is not going to be done on a specific budget, however I have been keeping track of what I have spent on the cycle. Less than $500 to date.

bjatwood: I have a soft spot for second gen camaros and hope to own one at some point. You spent $12,500 for a $9,500 car and thousands of dollars worth of knowledge. Totally agree with you and I will build it right.

Feel free to chime in anytime

Terry

[bjatwood]

Ya Terry, 2nd gen Camaro's get no respect... they handle very well, and overall GM did alot of improvements over the first gen Camaro,

[NagChampa]

Took a bit of time and worked on my Skate yesterday, Did not do much, just removed a lot of crud from the frame for the most part. Also decided to do something about the mouldy rusty seat that came with the bike. Took it apart to see if there was anything I can salvage but sadly the only think worth saving was the document pouch. Ended up throwing it in the bin and my garage smelled better instantly.

Last post I had removed the motor but did not post pics.







Really need to invest in shelving as I am running out of floor space at an alarming rate.













Some of the crud I have been scraping off these filthy bones. Self oiling chain system is a little too messy for me, have to do something about that.



Another pic of the damaged passenger peg triangle that will probably be removed in time, plan on running a solo seat with rearsets.





Here we have the mouldy, rusty, smelly, oversized seat section.








Not much good here



Or here


And some shots before cleaning











Still have to take pictures of it cleaned up but I may just start tearing it down further, have to drain the forks and remove rear wheel, swingarm, etc., then time to decide on paint or powder.

That is it for now everybody, getting married to my lovely lady this weekend and will be in Europe for the next couple of weeks. Not sure if I will get another post in before then, hope to get back to this project shortly after returning from our honeymoon.

[Nic]

Have a good honeymoon mate. I would strip the frame completely and I would just sand blast and paint, my basket case has had the frame powder coated when i got it and I reckon paint is better, when that powder crap chips it leaves big deep gouges and it chips real easy. For touching up the odd scratch that you'll get putting the motor back in paint is much easier to blend than the deep gouges and please, don't hack off that triangle, pleeeeaaaasssseeee.

[NagChampa]

Been back from vacation for a little while now and wanted to check in.

Had and amazing time in Paris and Amsterdam. Feel truly blessed to be able to visit other parts of the world, meet new friends, and have new experiences.

Have not touched the bike much since getting back but I have removed the rear wheel swing arm combo and the forks.

My plan was to remove the bearing races from the frame as I would like to change the bearings before reassembly. I can knock the top one out no problem but the bottom race is not as simple. I tried to use a long screwdriver but there is not enough contact area for the screwdriver. Might have to bring it somewhere to remove it but would rather do it my self. What is the proper way to remove them? Heat? Grind a groove in the bearing for the screwdriver to catch?

Here a couple of pics of progress


Brakes


Swingarm and rear wheel

The rims look like they could use some new spokes and a good polish. Might try some wider rims if it will work.

Will take more frame pics in a few days.

[NagChampa]

Has been a few months since I have updated this thread and for most of the time, the bike has just sat lonely in the corner of the garage while I worked on other projects around the house and garden. In addition, the motor that came with the bike has a nasty hole in the lower case caused by a loose chain I assume.

Because of this, I had been seeking a replacement motor at a reasonable cost. I ended up with a second motor that also had problems with the upper case that made it also useless. Not too mad about that because I got the second motor for a song and now have more extra motor parts than I hope to ever need.

Still needing a running motor, I answered an ad on Kijiji and purchased a 1978 cb750F3 project bike that had been disassembled and packed in bins. My original intention was to take the motor and small parts for the K3, then sell the extra parts to offset the cost of the parts bike. Seeing how the F3 came with every part needed, I decided I will rebuild it before completing the K3

Got the frame, tank and various bins of parts to my house then decided to not use the motor in the K3.

Instead I will be building the F3 and the K3 will go on the backburner while I try to source yet another motor or set of cases that I can use in lieu of the 2 damaged sets I currently own.

Because of this, my plans for the K3 have also changed slightly. Originally, the plan was to build a solo seat bike and get rid of the passenger triangle mounts. Now that I have a second bike, the K3 will remain a 2 up bike. I will have to remove and replace some of the tubes on the right side pass triangle because of the #$%* welds from when there was a sidecar welded on the frame.

Will go a little larger budget than I had originally planned and I will also take more time to make it right.


My wheel collection, 1 set spokes, 1 set cornstars, cbr600f4i rear wheel and there is a cb350 drum brake front wheel in the mix somewhere.


2 frames, K and F with tanks


3 motors buried in this pile of poop, not much room left with 2 bikes in parts. Give credit to all those guys who are working in a shed or out of the back seat of their pick up trucks.


SuperSport badge

 

[NagChampa]

Tore the engine down to an empty case, was less scary than I thought it would be. Only thing left is to remove the countershaft bearing. The cases will likely be powdercoated after being cleaned.


Upper Case Bolts


Lower Case Bolts








Have not had much time to work on this, when I do have time, there is no money. Either way, I still enjoy my time spinning wrenches at my own pace. Sometimes the garage is the only place where my opinion matters, it is the place I plan for battle, as well as the place to lick my wounds and recover. It is the place I go when I need a minute to calm down.


Got this guy completely broken down. I was contemplating just doing the top end, decided to open the cases up to inspect the gears. There is a good chance this motor will be powder coated in the near future so I spent a day scrubbing and rinsing. Pretty sure that all plugs and everything else has been removed, will give it a once over before it goes out for blast and powder.


This fell out of the motor once I separated the lower case assembly, anyone know where it goes? Will keep an eye out for it in the assembly manual.



After some scrubbing




Found a rear wheel that I might use on this project, might save it for another


Also trying to figure out what this is for, thought it was a wheel spacer.

Broke down the F1 wheel for cleaning and threw the rusty hoop in the garbage, I need to order the 6 bolts for the brake rotor. Might send this for powder and will be ordering a new rim.

As she sits today


Cordless drill and angle grinder to fab up some new shock mounts, the mounts are in the same place as stock.


GL1000 front end to compliment the F1 wheel, should I decide to use it on this project. Missing the bolts that mount the brackets to the forks, must order some although they seem to be discontinued most places. Anyone have an idea for a replacement? Pretty sure it is 'bad juju' to buy a used bolt for any part of a braking system. Should I just add this to my list of parts needed from CMSNL? Is there a hardware store solution that is less stressful and just as safe?

Will build 'er with the Comstar wheels, get it running and the bugs ironed out. Will decide later if I want to switch to the spoke wheels or save them for something else.

For now I am searching for engine bearings, seals and anything else I need for the bottom end.