Topic: Humpty Dumpty cb750 Build

[calebsayshi]

Hi guys,
I'm new here to SOHC4 forums and to bikes in general! I only got my bike license a month ago and started thinking about what kind of bike to buy for my first. Started looking at prices and realized that there was lots of modifying that I would have to do on top of the purchase price because I don't like things completely stock! I had seen a couple of Cafe Racer style bikes on my Instagram feed and fell in love! So I started to keep an eye out for an older bike that I could completely build and these two fell into my hands!
I picked up a 73 and a 74 for dirt cheap as a package deal. As you can see they're not in the best shape and have been really parted out. (+) I won't have to try to sell lots of parts as I upgrade them but (-) I have SO much work in front of me that I don't know what I'm getting myself into.





And here's the 73 that's going to be sitting for quite a while as I'm going to build the 74. I also got a free bicycle that was thrown out that I'm going to refinish and sell to pay for some bike parts!


Plans I have:
GSXR 1000 forks and dual rotors (dark bronze)
Full Motogadget electrical (motoscope mini, m-unit, blaze disc turn signals)
rear disc instead of hub
full custom carbon fibre tank and seat back (DIY style )
keihin carbs (not sure which ones yet)
superbike bars (I'm not sure how I feel about clip ons yet)
eventually bore the cylinders and do forged internals
Not sure what's next

A bit of background on me as I do this build completely from scratch with NO experience:
Just finished collision repair school and starting as a bodyman soon (I just got a job today!)
I am a car guy through and through, but I think this might change as I work on Humpty Dumpty
I am 22 years old with no mechanical experience but a HUGE desire to learn as I go
I'm a stickler for good design and don't want a shoddy bike when I'm done building

I'm not really sure what to expect for what it's going to cost but I imagine close to 10k when all is said and done. But I'm going to do my best to keep it below (who knows how well that'll go!)


My plan is to start with the frame and get it looking like a motorcycle again before beefing up the motor. I'm going remove the motor and work with the frame first and rebuild the motor slowly as I go.

I have made an excel Doc with all the parts I plan on purchasing and where I'll get them. This doc will change significantly throughout the build and is by no means final or completely accurate. I'll add the link to that in another post


Welcome to my crazy adventure!

--Caleb--

[Restoration Fan]

First of all, Caleb, welcome to the forum.
You picked the exact right place to put a build thread.  The people on this forum are the most helpful people you'll ever come across and there are some absolute SOHC gurus on this board.

Are you going to stay with spoked wheels or going with mag-styled wheels?  If spoked style, have you already sourced a rear, spoked wheel with disc brakes?  Just something to think about.

Also, do you have carbs?   Neither bike shows them in the photos.  I know you said Keihin but I'm guessing you don't yet have them because of the "don't know which ones yet" statement.  But the ones that came on that 73 or 74 were excellent carbs and I like them because they have the choke linkage on the carb itself, instead of needing a choke cable like the later model bikes (77 & 78 specifically).

Regarding cost, you can easily come in less than 10K if you don't go with a ton of chrome.
There's a member on here named Bill Benton (BillBentONRacing) who has about 50 or so of these 750's in various stages of completeness / parts.  He's an invaluable resource for sourcing hard to locate parts for these bikes and he's also one heck of a great guy.

Ron

P.S.  (Oh, and unlike Humpty Dumpty, hopefully you won't take a great fall on your bike when it's done! )   

[calebsayshi]

Thanks RF!
In regards to the wheels, I was originally planning on going with a CBR front end and using the mags from said bike. But I've decided on the GSXR front end and after seeing the dark bronze with black stanchion combo I knew I had to do spoked wheels (black spokes and matching anodized rims to complete the look). I've been looking into the front wheel quite a bit and I am leaning towards the billet conversion hub from Cognito Moto but I haven't decided on wheel size or where I'm going to get the other components.
As for the rear, I haven't looked into it yet actually. Do you know of any place that I can get the disc conversion that would be recommended?

As for the Humpty Dumpty name, it comes from the fact that I picked up the bikes in pieces. I think I may need to change that though haha