Topic: 1977 CB750k restore project

[dgilling]

I got this beautiful bracket made by the machinist at my work (for Free!).  He even got it anodized.  Only mistake we made is that we made it slightly too thick.  I had to find some smaller nuts and I still couldn't fit a lock washer on them.  I just used some blue loctite though and called it good. 



bolt just barely fits. 



You can't see all of it but I routed the clutch switch down the insulation for the left control to make it look cleaner. 



If I would have known how hard it would have been to organize all the cables and junk behind the headlight I probably would have simplified a lot of things.  It's so hard to make that stuff look nice back there.  I need to modify the chock bracket and relocate.  after that I should have all the cables.  I'm still waiting on my right turn signal bracket.  Once I get that then I will button up the electrical and move on to starting the bike. 



Getting close!  all systems seem to be working correctly.

[Restoration Fan]

Cal,
That's a beautiful wiring job.  I see the M-unit back at the rear by the battery but is that rectangular unit in the middle the control module?

Ron

[SOHC4 Cafe Racer Fan]

Cal,
That's a beautiful wiring job.  I see the M-unit back at the rear by the battery but is that rectangular unit in the middle the control module?

Ron

C5 Ignition?

[dgilling]

I'd love to eliminate that nest but the goal is to just get done at this point.  Maybe when I redo it again in 10-30 years

[SOHC4 Cafe Racer Fan]

Cal,

Have you used the M-button wiring on any bikes.  It looks like all the wiring goes into the connections of the M-button, and then a single fiber optic cable goes to the M-unit.

Don

[SOHC4 Cafe Racer Fan]

Yes, several. Correct about the single wire (it's not fiber optic though).

It's more awkward with clip ons but still advantageous.

Cal,

Do you prefer using the M-button or running all of the wires back to the M-Unit?  And why (aside from the choice of bars)?

[dgilling]

I actually enjoy the wiring part and getting things to work, I hate organizing. 

[madmtnmotors]

Does the brake hard line run on the inside or outside of the fender?

I just sorted mine this evening. The hard line goes between the fender brace and the fork tube in order for the hard line/flex line junction to hang from the fender clip. The upper caliper bracket also goes between the fender brace and the fork tube to provide enough clearance for the hard line. Your fender brace is against the fork when the caliper bracket should be against the fork with the fender brace inboard of that.

From the manual:

[dgilling]

Well the bike started right up and sounded great. As soon as I hit the start button she purred like a kitten.

Bad part was the #3 carb was leaking gas out a screw near the top of the bowl. The gas leaked onto my engine and peeled the paint.  I used duricolor engine enamel and figured the paint would be way more durable. I'm not sure why it didn't hold up to the gas and I'm not really sure how I should clean it up

The gas leaked out the screw on the intake side of the carb that faces the front of the bike. Not sure what to do about that either. 

I'll post pictures of the damage tomorrow.

[dgilling]

Here you can see the screw where the gas was leaking and some of the damage below. 



sighhhhhhh



So close... now so far from done. 

[mkoski]

Thats a classic right there, leaking carbs ruining new paint. Not much you can do about that now.

Things are looking good man, I really like the gauge setup with that super-clean tach. 

[dgilling]

How do you keep this from happening?  and how do you cover it up?  It seems like the paint would be way more durable then that.  I feel like it should be totally cured by this point since I painted it months ago. 

[dgilling]

Cal,

do you know why the carbs would leak here?  I guess that's my bigger problem. 

[mkoski]

You are missing the oring in there, I would bet. She's really tiny, most people dont realize there is one in there.

[dgilling]

does that come with removing the screw?  All I did to the carbs was remove the bowl and clean up the varnish and gum.  there wasn't much since did a full rebuild a few years ago.  could I have misplaced the oring that you speak off by removing the bowl?

[mkoski]

When I pulled my air screws out they stayed inside the hole. I would say pull your carbs off the bike, unscrew the screws and use a light to look inside the hole. If you cant see an oring in there, you will need to add them. If you can see an oring, get a piece of wire and pull it out for inspection. Realistically, you are going to need to get all new orings for those little guys if you want to stop leaks, I think

[Davez134]

As far as the paint goes, did you heat cure it? As soon as you fix that leak, scuff and re spray that area. Then let the engine run/heat up and cool down a few times, making sure nothing spills on it. I use vht spray engine enamel, and the heat curing makes all the difference.

[dgilling]

As far as the paint goes, did you heat cure it? As soon as you fix that leak, scuff and re spray that area. Then let the engine run/heat up and cool down a few times, making sure nothing spills on it. I use vht spray engine enamel, and the heat curing makes all the difference.

I didn't heat cure it.  but I shot the paint months ago.  I was hoping the engine heat would help with that but the carbs leaked right away. 

 

[SOHC4 Cafe Racer Fan]

Heat curing (from running) helps cure over time, but baking (or hot boxing) before assembly helps harden the paint before it is subjected to chemicals, etc.

Powdercoat is more resistant to chemicals such as gasoline, but you are past that now since the engine is assembled.

[dgilling]

I'm such an idiot.  I didn't tighten the bowls all the way.  I guess after turning a couple hundred bolts you might miss one or two. 

After I did that the leak basically vanished.  however I could still see what appeared to be a very minor tear drop of gas forming on the same place. 
I put the carbs in a bucket and turned gas on to them.  This is the leak that I saw forming when it was on the bike and running too (after I fixed my main problem).  I ordered an Oring kit, so I guess I'll open all of them up and replace them.  I'm hesitant to do #1, 2, and 4 since they seem fine.  last time I replaced them was about 5 years ago. 

You can see the gas forming in tear drop fashion.  it moves very slowly but still something I'd like to fix. 



I pulled the carbs and started sanding.  It didn't eat through the primer so I think I'll just sand and clean the best I can and reshoot on top of that.  When I was sanding the paint acted like it had a good bond.  Flybox and few other forum members were saying to use acetone, take it all the way down, and re-primer/paint to remove any toxins or reasons why the paint didn't have a good bond.  I just don't think I want to do that.  I feel like it would probably be the same outcome either way.  Hopefully, I'll get some new paint on top of this stuff, run the motor, heat up the paint and get a better cure.  Oh, and fix my leaky carbs. 

[dgilling]

I got  everything masked off and painted.  Overall it wasn't that bad and didn't cost me too much extra time.  the paint looks descent.  There's no lines where I masked off which is good.  i got a little bit of a splatter blast towards the end that is visible but over all no one will ever see it.   

Now, install new orings in carbs, put everything back on, and heat that engine up to really cure the paint. 

I'm basically waiting on the following before i can call it done.

I need to install the chain and remove some links, i don't have a tool to do that. 
I need to weld the rear fender (will do that over memorial weekend with my Pops)
Cut front fender
Sand and paint both fenders
Install new seat, still waiting on the kit to come in from Vietnam. 
add DOT fluid and bleed front brake. 

After that I ride into the sunset. 

[dgilling]

forgot the pics.

[madmtnmotors]

Does the brake hard line run on the inside or outside of the fender?

Did you get the hard line from the caliper corrected? It should look like this:

[dgilling]

Does the brake hard line run on the inside or outside of the fender?

Did you get the hard line from the caliper corrected? It should look like this:

I did not move it yet but this info is extremely helpful. Thank you very much for the reply. I'm going to look at this tonight. One of my problems is I had to move the brake switch up to clear my headlight bracket. That changed the angle on the hose. Hopefully everything still works close to the same.

[dgilling]

this had to have been leaking because there was gas up in the hole


Found another source of the leak



Well I tried to avoid this but it had to happen.  replaced all the orings from a kit. 



And everything reinstalled and did a quick start to look for leaks.  didn't see anything but I need to run it some more.


Snapped this off trying to get the hose off that hondaman gave me.  I thought he said 5mm hose is stock size but it was super tight.  it went on but, was obviously hard to get off.  What size does every one else run?


Got the chain installed but didn't Measure twice, cut once.   Miscalculated and cut too short.  Anyone need a DID 530 chain with 102 links on the cheap?

about 3/4in of slack.  Super tight.