New rider and new project, DOHC CB750C cafe

[shaggycb750c]

Hey everybody, the name is Shaggy, or Shags, or Shagadelic, or any other pun on Shags that you seem to like. I live in the Northern VA / DC area, and have been looking for a bike for some time, something that fit my budget, (which is near to nothing), and came across this little gem for a scant $150 through a friend without a title. It's a 1981 CB750C. I got the bike from the title holder, but he no longer has it. So that's first on the list to get done. Second, get my license, as this is my first bike. So with my fathers pickup, I took it home to where it sits now. I got to go over it a little more thoroughly and would appreciate any input or opinions as I go. Anyways, here's how it sat as I first saw it.

 

[Rich Ard]

I'll bite - why is there painter's tape on the valve cover gasket?

Welcome to the forum, Shaggy.

 

[shaggycb750c]

Here's some closeup pictures as I got it home, I discovered quite a bit missing. It's only got half the exhaust, (2 headers, 1 muffler), and looks as though the motor mounts are missing. Quite a bit of bondo up on the tank, too. The carbs seem all complete, but they do seem a bit locked up. My only fear is that without the header, a valve could have been open and rusted out a cylinder. Sorry bout the blues, my camera phone is quite a piece of junk. Anyways, on to the pictures

 

[shaggycb750c]

Haha, for quite some time, I thought it looked like tape, too. It's the blue reflection of the blue tarp that was covering it.

 

[cklamer]

WELCOME TO THE INSANITY! 8)

I am getting on the final stages of my CB750K build.
I do have lot's of extra parts lying around so if you need something let me know.

 

[canyoncarver]

Welcome Shaggy, gonna call it Scooby? lol. Sorry I had to get that out of my system.


Anyways, congrats on your bike. Do lots of homework, ask lots of questions. I have a DOHC 750 too. Cool bike.

 

[shaggycb750c]

Hey cklamer, I definitely will be needing some parts. Just to start out, I need the other half of the exhaust, lol. Got a build or fs thread?

 

[shaggycb750c]

Okay, so first update. I got a bunch of parts taken off the bike to get a good image of the real condition of the bike. A little surface rust here and there on the frame, but overall good shape. The engine appears to be in fairly good condition, but as of yet I haven't had the opportunity to try turning the engine over. Tank, rear fender, carbs, chain, and wiring harness have all been removed. After pulling apart the carbs, I found a bunch of crud in the bowls, and they reek of varnish. As the petcock came off, there was a bunch of red veal in the gas tank. I assumed its rust, but its the same color as the veal in the carbs. I think the first item to purchase is a rear hoop so that I can spend some free time on making a seat, then a new hammer to make knee pockets, and finally a carb rebuild kit. I hope to have this finished and ready as a birthday present to myself as my deadline, which is new years eve. Pics tomorrow!

 

[Rich Ard]

Get it running first. Also there should not be any veal in your motorcycle, that's gross.

 

[hillsy]

Your tank already has indents at the back - don't waste your time on knee dents.

Just concentrate on trying to get the bike to run.

PS: Did you get a couple of boxes of parts with the bike or is the rolling chassis as per the pics all you got? If not, then you need A LOT of parts before you have a runner.

 

[Hoosier Daddy]

Welcome! Nice to see another C model make it to the forum.
These guy's are right, at the very minimum pull the spark plugs a add about a teaspoon of oil to the cylinders, then take off the timing cover and put a socket on the crank shaft and try to turn the engine over. Don't want to waste a bunch of time and money on "look pretty" if it is siezed.

 

[shaggycb750c]

Well I already have the bike in my possession and these are all things I can do for free. I haven't been able to locate my socket set small enough to take off any of the covers on the engine, so I just haven't gotten to that yet. The only one I have gotten off so far is the pulse generator cover as it was held on with phillips head screws. Little bit of oil down in the bottom. Harness looks great and unmodified. Until money comes in to rebuild the carbs, I can't put any focus on getting it to run. It also has the issue of only having half a header. So just to get it to run right, I'm out for at least $300.

 

[clem]

I'd have to agree on your assumptiin on if one exhaust valve was open with no headers that bad things can take place. It may still run but will smoke a bit due to rust damage/ pitting on the cylinder walls. I kept a well running bike at the time inside a shed with no headers on it and never bothered the set the engine with the valves closed. Needless to say I screwed up royally.

 

[Rich Ard]

It also has the issue of only having half a header.

Ha. Ye shall overcome!

 

[Hoosier Daddy]

The only one I have gotten off so far is the pulse generator cover as it was held on with phillips head screws. Little bit of oil down in the bottom.

You're right, I should have said the stator cover. That is held on by bolts you will need an 8mm (5/16) socket for.
And yes, on these DOHC motors there will be oil inside the timing cover. Not like the older engines with points (contact breaker) ignition where oil would be a bad thing.

 

[shaggycb750c]

And on to the pics!
First up, how it sits now


Parts removed


Inside the stator cover


Dirty dirty carbs


The "veal" inside the float bowl

 

[shaggycb750c]

This weekend's update, got some more stuff done. I took the front end off to get the headlight brackets off the fork tubes. To get those off, I had to get off the front brakes and turns out one of the brake calipers was slightly clamped on the rotor, this made pushing the bike around the yard very difficult. Not ever owning a motorcycle before, I assumed that was the norm like "hey, it's just difficult moving these things around." Not the case... While the front wheel was off, I broke the bead and replaced the valve stem, so now both tires hold are. Turns out it's actually pretty easy moving around. Cleaned and regreased the steering stem bearing, and got the valve cover off to get a better idea of the engine condition. Everything looks good up top, but looking at the valve tappet, there were valves open on the engine. I'm taking my smaller ratchet set home today to get the covers off and see if this thing will turn over. I have a sneaking suspicion the cylinder may be rusted out... So... pics for the day.

As she sits now


Looking down the cams


Open valve


Stem bearing


That's all for today!
Shaggydoo

 

[shaggycb750c]

This weekends update, although small is pointing in a good direction. As suggested, I poured a little oil in each cylinder, and had no trouble spinning the engine at all! Seeing the engine and rotor in reasonably good condition make me think that there might not be anything troublesome other than the gummy carbs. Wish me luck!