My '80 CB750C 'Resto-Mod' Build Log

Hi all. I figured I'd start this thread to document the transformation of my new-to-me 1980 CB750C. I managed to pick it up from my brother for a box of AR15 parts. When we first started talking about the deal, I was gung-ho for a cafe build, but the more I think about it (from a practicality standpoint), I don't think that's the route I'm going anymore.

Here's how she looked when I first started going over it:


Battery box and top of swingarm are pretty cruddy. Almost like the battery boiled over at some point. And go figure, no right side cover. Seriously, where the hell do they all go?


Shy of 20,000 miles. My '05 Suzuki C50 is at 18,500. It's like this CB is just getting broken in!


The tank is a little banged up, but overall it's not too bad. The inside of the tank looks immaculate.



Issues identified so far:
No clutch cable
No battery
Front brake lever is broken and pulls all the way to the grip
Key doesn't turn the lock cylinder
Based on the crud on the backside of both forks, I imagine the fork seals are shot
Chain adjustment is maxed out and the chain is still sagging, so I'm guessing a new chain (and sprockets?) is in order

On the upside - aside from a little bit of surface rust, the bike is very clean. Also, I have yet to come across a single spliced wire!

As of right now, I'm still undecided as far as what direction I want to go with this bike. First priority is to get it running and see what it needs before I jump in to any modifications. Today I managed to get the following done:

Clutch cable installed and clutch adjusted
Front master cylinder flushed and bled
Battery installed
Ignition switch pulled and new keys made

I'm going to put some gas in it tomorrow (it's currently living in my brother's storage unit until my Suzuki is sold, then it gets to come home) and see if it will fire. I can work on troubleshooting any other issues after that.

if the teeth on your sprockets become pointy you better replace them as worn out sprockets will make your new chain wear faster...

Nice score on the Custom! Since you're not too keen on a Cafe' at this point and a little undecided, I'll just drop these off here...

Quick update -

I put some gas in it and she fired right up (after a little cranking). I let it idle for a few minutes, then changed the oil.

She idles really smooth. I took it for a quick spin around the parking lot, and everything felt pretty good. It shifts really nice, especially compared to my Suzuki. I did notice the rear brake seemed to be dragging slightly. When i got it back up on the center stand, I noticed the brake lever was hitting the bottom of the foot peg, so I adjusted that.

jungalist said:

if the teeth on your sprockets become pointy you better replace them as worn out sprockets will make your new chain wear faster...

Click to expand...

Thanks for this. I wasn't sure what wear I should be looking for (my other bike is shaft drive). Aside from the gunk, how does this sprocket look to you?





Oh, and I don't know if the chain stretched, or if it's just the wrong size:

Hoosier Daddy said:

Nice score on the Custom! Since you're not too keen on a Cafe' at this point and a little undecided, I'll just drop these off here...

Click to expand...

Yeah. Thanks. LOL.

I've gone through a few different setups on my Suzuki. I'm planning on keeping this bike 2-up friendly. I like the overall look of the bike, so I'm just planning on some subtle changes as of right now. I already plan on changing the handlebars, turn signals, and probably the taillight. I know one of my next steps is going to be cleaning up and painting the pipes. I may wrap them too, but haven't decided yet.

Here are a few shots of my Suzuki. They really show my taste changes all across the board

Another quick update. Yesterday I went through the bike and started working on some of the rust. I picked up some Rust Reformer from Rustoleum. Wow. If you're not familiar with it, it neutralizes the rust and leaves you with a paintable surface. Very cool stuff.

I also pulled the exhaust to clean it up and hit it with some VHT header paint. Since I was planning to do this as one of the first steps, I had already ordered some exhaust gaskets (along with new levers, front springs & seals, etc). One thing I want to be sure of is that I get the old gaskets gone. So, my question is this:
Looking at the picture below, is the thin double layered section at the end of this header tube the gasket?


When I pulled the pipes, I looked at the exhaust ports and didn't see anything that looked like a gasket, so i was wondering if these are them, and if so, do I just knock it loose with a screwdriver or pliers?

The original were copper rings that crush when the exhaust flange is tightened. I have seen aftermart ones that are like an asbestos fiber inside of a metal ring. The aftermarket style appears to be stuck on the end of your headpipe. But you should be able to grab it with your hand and remove it with a little twist.
All too often you will find two gasket in the exhaust port because to guy working on it before you didn't see the previous ones and stuck new ones on top.
If you are looking in the port with a good light and see the aluminum head, not just black carbon, chances are in your favor they aren't there.

Thanks HD. I took another look at the exhaust ports. There was a gasket in each one (looked like fiber wafer sandwiched between 2 pieces of copper). As for the bits at the end of each head pipe, I put a flathead screwdriver at the small step where the 'seam' is and gave it a few good whacks with a hammer. It was a no-go. Since I will likely eventually go to a 4-1 setup, I'll just reinstall the pipes with the new gaskets I ordered and call it good for now.

I bet you are fine...

More parts have started coming in, so I managed to get a little more work done today. I'll apologize in advance for the crappy iPhone pictures.

First, it's important to have a spacious work area...


Today I decided to tackle the fork seals. I'd guess they were a little past gone.


On one fork tube, I found what I can only describe as scuffing:


And on the opposite side of the same tube.


Is this tube okay?

Since I had everything apart, I installed the Progressive springs I ordered from DCC. The spring kit is PN 11-1106, which Progressive shows as the correct fitment for the 750C, but they are a bit shorter.


Thoughts?

You'll need to cut a longer preload spacer, probably from PCV is easiest.
Instructions from Progressive should give you a base install length.
You can adjust prelod by cutting off 1/4" increments afterwards

^ This is an assumption based on a few similar Hondas I've dicked with, but I'm no expert.

I'll take a look at that. I know the springs I got for my Suzuki came with a piece of PVC. These didn't. Nearest I can tell, their site indicates these are OEM replacement.

Unfortunately, i haven't really been keeping a photo record of this build. Since I have some more changes coming soon, I figured I'd drop off a pic to show how it currently sits.

I guess I will call this "Phase II" with more changes in the works...

Phase III in progress. Ordered a seat from an eBay seller in Vietnam on Aug 17th. It was delivered on Aug 29th. Not too shabby.

Chopped tail section:


Tail hoop test fit:


Seat test fit:


Still sorting out mounting of the license plate, tail light, and turn signals. Phase IV will be at the front of the bike...

I LIKE IT !!! ;D