Topic: First bike build 78 CB750K

[Mule169]

Hi, first post on my build thread.



Don't know if this is the right place for a build thread, as I'm a bit new to this particular forum, but so many folks have been so helpful over PM (@HondaMan and @calj737 to be specific) that I figured I make a thread, and maybe someone could learn from a mistake or two of mine.

I'll preface this with, this is my first motorcycle build, I've ridden bikes, but never really done much of any working on them.  I had a hip surgery last winter and needed something to keep my brain occupied as I couldn't ride or race my pedal bike much for a year.

Anyway, I've learned a ton, and I'm closing in on getting the thing finished.  Always happy to hear criticisms, or feedback as the bikes not done yet and everything can always be better!

So here's the bike that I traded a website build for.  I knew I was going to pull it completely apart, so it was a bit rough, but it ran! It looks better in the pictures than it did when I started pulling it apart!

While I did decide to wreck modify this guy quite a bit, I'm already on the hunt for project #2, something that I can restore back to it's original look.





More to come!



 

[Mule169]

Step 1:  Tear the bugger apart.







Get the motor out of the frame





Get them mounted up on stands:



And get the workshop setup:

[Mule169]

I decided to go the way of the masses and cut the rear of the frame off and weld on a loop.  As I write this I know this probably wont' be a very original build, and probably boring for most folks.  But it's my first bike, and I probably just got used to the look that I saw so much when reading forums, and gathering information while deciding to tackle this thing.



I also de-tabbed the frame, you know all the bits and bobs that made things look all cluttered.





I tried to just sort of mock things together to see if I cut the frame in the right spot.

[Mule169]

So, after the things was apart, frame sandblasted, de-tabbed, and cut for the loop came probably my favorite part of this whole process for me.  I have always wanted to learn how to weld.  I thought hard about having someone do all the welding on my project as I was a bit nervous that this wasn't just a coffee table, but rather something that will be taking me down the road in the future.

But, I started coming up with parts I wanted to build, and realized that I'm only doing minor welds on the frame, none of them are really "structural", or at least critical weld points, so I decided to take a stab at it.  I live in Portland, OR which has it's annoyances, but one of the cool parts is some of the shared shop spaces that are available.  I paid for a month at a place called ADX where they have a number of very capable TIG welders.

So I bought some supplies, a rear loop from Cognito Moto and started to practice.  I spent about 2 weeks just practicing on free scrap in the shop, asking questions from folks more experienced than I, and then practiced and read a ton more.  At the end of the day, things my not be as pretty as they could be but I managed to do some cool things (in my mind anyway).

Lets weld!



Fast forward to...





So, now on to all of those other ideas I had that involve welding!  I have a friend who works as an administrator at a well funded rural school.  They have a really magnificent trade education program there.  They happen to have all sorts of 2D CNC equipment there, one of which is a CNC plasma cutter.  I had a few part ideas floating around in my head, and a couple that were inspired by Devin the Cognito Moto dude's build that I read I don't know how many hundred times. 

My buddy mentioned that if I drew up the parts, and bought the steel, that they would be excited to use my parts for a class on how to use the plasma cutter.  So, I had to figure out how to use a CAD program to draw up the parts I wanted.  Drafting is just about as tedious, and hard to learn as welding 



All of those flat sheet metal parts lead to:

Battery/Electrics Tray



Oil Tank - I cut most of the fittings, and innards out of the stock oil tank, and re-used them in the tank I built.  There are some mistakes in how I did this that will be fun when trying to drain the oil, but it will be functional, and I can always build a new one down the line if I want.









Then I got some rubber mount tabs, welded them to the frame, welded some bungs into the oil tank, and this is how it should sit in the bike when it's all done.



Here's how it sits with the electrics tray

[Mule169]

I only have one picture of the seat pan that I built, and it's only part of the way through here.  I'll try and get some additional images of the whole seat pan/tail loop/seat latch setup that I dreamed up and post them here as an edit. 



It may be a complete pipe dream, but basically welded a steel plate to the underside of the subframe/rear loop to enclose that whole section.  I welded so support cross struts, and bungs in to allow me to easily mount/unmount a frame with some small bags for weekend trips on the underside of that plate/subframe. 

I built the seat pan with about 3/4 rise to allow a cavity between the bottom of the seat, and the pan I welded onto the rear sub-frame.  This is where I'm going to mount all my electrics, as well as a solenoid for opening and closing a latch that keeps the seat locked on.

I welded 4 posts with holes drilled the length of them onto the subframe, and 4 pins in corresponding locations on the seat pan to slide in and rest on the posts.  The latch will keep everything secure.  It's not the prettiest, but it looks like it's going to work, and with powder coating on the frame it smooths over some of the first timer mistakes.

[Mule169]

Next up, Powdercoat!

I pulled apart the forks, to allow me to get the lowers coated.



Pile of things to get the powder treatment



Frame and swingarm are going to be this gold color, and the rest of the parts are going to get the matte black treatment.  In the photo below, you can see the 4 posts that I welded on that will accept the four pins from the seat pan, and provide a little more than a 1" cavity to stash electronics, and latch mechanisms.  You can also see the bars/bungs I welded in to support bags that will be attached from the underside of the tray there.



The next thing I tackled was lacing up wheels.  Yet one more thing I've never done.  I read a bunch, and this article helped me out a ton!

Front all laced up



Rear about ready to get it's spokes

[theslayedsaint]

Sweet build, looks like it's coming along nicely.. Also nice hat! I'm also from Portland and finishing up my first build hoping to get it done soon as the weather seems to be getting better.

[calj737]

Looks really good for your first effort. Just make dead certain that your oil tank is pressure tested before you go much further on it. TIG welding can create lots of tiny air holes, especially along seams and as a new welder.

[Mule169]

Next step for me was to turn to the motor.  This one was a tough decision in this build.  I'm one of those people who likes to take everything completely apart and understand how it works.  Especially with older things, I get so much satisfaction from pulling something apart, cleaning every bit and bob, and then putting it back together again with it in perfect running order. 

The bike ran well (not great but I think that had to do with the general state of maintenance rather than anything wrong with the motor), and I did some back of the napkin math about how long I thought it would take me to really pour through the motor, learning as I go, replace/upgrade things along the way, and it really just didn't add up for the first go around.  I'm pretty sure I'm planning on having this bike for awhile just as a project, so I think next year, my project will be to tear it completely apart, so some fun modifications, re-paint, generally completely overhaul to perfect condition.  I'm taking a bit of a gamble that it's in relatively good working order now, so that something blowing up isn't the catalyst for the motor rebuild project 

Anyway, I elected to clean, paint, and re-install and replace gaskets that needed to be replaced. 

Not as bad as some motors I'm sure, but this thing was hella gross. Degreaser, paint stripper, scrubbing, scrubbing, scrubbing, scrubbing.  I finally relented and called a C02 blaster that is in the area.  I read a bit about it as it is rather non-destructive, and doesn't leave any abrasive anywhere so using it on a well masked/sealed motor to finish cleaning the parts I couldn't reach made sense.  It was an added bonus, when I got to the blasting shop, and I found out an old high school buddy owned the business.  He cut me a HUGE break on the cost as I transported the motor over to his shop and he used excess C02 pellets from a job he finished later that week.



I cleaned every surface I could within an inch of it's life with acetone, and then gave it a couple coats of high temp engine primer







Then a couple coats of matte black high temp engine paint







I also splurged a bit and bought some polished alu hardware to make the black kind of pop out a bit.



So, then time to bring the frame/motor together again.



Used the often cited motor on it's side, and drop the frame over.  The motor is laid on it's side with some support blocks under it to keep it level.  The blocks had plenty of padding/rags to not scratch the paint.









I would recommend getting a friend to help with the whole mating of frame/motor.  I was able to do it on my own, but I had a couple moments when I realized I wasn't as strong as I used to be/thought I was

Steering head bearings, which I replaced with the All Balls tapered bearings, were next.  The requisite freezing/heating of various parts worked like a charm, and things only had to be mildly coaxed into place. 

Lower triple still frosty from the bearing installation

[Mule169]

Looks really good for your first effort. Just make dead certain that your oil tank is pressure tested before you go much further on it. TIG welding can create lots of tiny air holes, especially along seams and as a new welder.

Thanks Cal, glad to hear you suggest this!

There were some pinholes in the tank, and I was for sure scared off from welding on a tank that had gas in it previously, so I took it to a radiator shop that does welding on big industrial gas tanks, and they blasted, braised, and coated the tank for me all for a VERY reasonable price.  They pressure tested the oil tank for me along with that whole lot, and I lucked out (yes totally luck and not skill as a completely novice welder as I've now come to understand) that there weren't any leaks!

I thought I might have been being a bit paranoid and over the top asking them to pressure test the oil tank.  Glad to know I at least have a small clue about checking my beginners work.

[calj737]

Welding new metal is easier. If you find yourself needing to weld the cases or older alloy parts, that's when you'll really find out, the heat from TIG will purge all dirt, grease, grime from the part, and it will taint your weld promptly. Only solution is to preheat it, clean it, heat it again, clean it some more, then cross your fingers and weld. And welding aluminum is a bit trickier than steel 

I couldn't see from the pictures the weld you made on the hoop, but don't grind it off for appearances. The tubing pretty thin, and you need the bead to remain for structural strength. Just make beautiful peas, and be proud 

[540nova]

Looks GREAT! You should be proud! Can't wait to see it finished!


Sent from my iPhone using Tapatalk

[Bootsey]

Certainly looks like a well thought out & well executed start on your project, good stuff.

[beemerbum]

Very nice work! Greetings from a fellow '77-'78 enthusiast for central OR.  Think I'll keep it original. I like the look of four pipes from the back

[Mule169]

Very nice work! Greetings from a fellow '77-'78 enthusiast for central OR.  Think I'll keep it original. I like the look of four pipes from the back

Beerbum, if my bike looked even remotely close to that when I bought it, I would have put some gas in the tank and not touched a thing!  That is a pretty looking ride!  I even teetered on trying to restore it to that original condition, but it probably would have cost me almost as much money and taken just as much time.  Plus I got to teach myself how to weld, and do all sorts of crazy things this route.

Where in Central Oregon are you?  I get out there every so often, great roads in the summer.

[Stev-o]

Nice project!  Subscribed...

[SOHC4 Cafe Racer Fan]

Fantastic work so far, especially the fabrication work!

[Mule169]

Ok, so this one will bring me pretty close to up to date. 

Next in line here was to get the forks put together and installed.



Magic



Mounted!







I had visions of mounting the headlight (top/bottom mounted bucket) to the upper or lower triple instead of on the forks with traditional brackets.  Once I got everything all put back together, I came to the realization that this would be a more time intensive task to dream up a cool mounting system, and fabricate it.  I still might do it, but for now I'm leaning towards just painting the old bucket, and mounting arms, and giving it the more traditional look up front there.  We'll see.  If that happens I'll have to pull the forks back off to install.  No biggie though, it's an excuse to drink a beer! 

One bummer that I just discovered when getting the wheels trued and rubber mounted was that the front rim had a flat spot.  Something I hadn't noticed when riding the bike home, or doing disassembly.  So, I had to fleabay a new rim, get it re-powder coated.  Small setback.

On to the electrical system.  In my head I decided that if I was going to restore this thing I'd try and keep the wiring harness as close to stock as possible.  Since I'm wrecking heavily modifying things, I decided to do the whole MotoGadget treatment.  I'm not an electrical dummy, but this is my first attempt into a wiring harness.  I got pretty far down the path, and @calj737 helped me immensely with some of the more complex fine grained details that I overlooked as a first timer.

So this is what I have, and I think it's pretty much done.  Any questions or suggestions are welcome!



One big thing Cal helped me clarify was that I was making the assumption that "black was ground" on the original wiring harness that I found online.



When it came to wiring up the Neutral/Oil Pressure switches, he pointed out hat the wires coming out of the motor case, that are ganged with the alternator wires on an 8 pin connector were the negative/ground side of those circuits.  This sent me for a mind warp as I was assuming black was ground.  I started reading and realized that on these old bikes, green was actually ground, and black contained switched power.  Cal mentioned the best thing to do was to trace each wire and see where it lead (to power/ground) rather than just rely on colors, etc.  The biggest problem I had with this was that in the original wiring diagram above, black and green look exactly the same (at least to my bad eyes).  To help me understand and finish out my harness when wiring up neutral/oil pressure switches I use the Preview program on my Mac and changed the color balance and all of a sudden, green vs. black magically appeared to my eyes.  Whole new world for me!

You'll notice the indicators for oil pressure/neutral, which were the two circuits I Cal mentioned that messed with my mind, have BLACK power wires going to them, when looking at this color shifted images.  Previously I just assumed everything on that top left row of indicators had neutral/ground going to them via the BLACK wires.



So, I'm pretty much ready to rip building this thing, I've got all the MotoGadget stuff, but one question I had was anyone have recommendations on electrical connectors I should use?
I'd like to use weatherproof connectors (even though they are more expense, some more expensive than others), but I didn't know if it's worth the money over just the OEM style connectors.

And while I'm soliciting information, I'm pretty sure I could go connector crazy when splicing (using connectors vs. soldering), making every component individually removable via small connectors vs. combining with one big connector, grounding via a big terminal block vs. splicing wires/connectors down to one big ring terminal connector?

Again I'm a bit new to this so my terminology might be a bit weird when trying to explain myself, but when do you make the determination to spice, use a connector, and bunch devices into their own connectors/groups?

Ok, so more to come this week as I start the wiring harness.  I'll also try and get some pics of the gas tank which I chose to do some knee dents, and the seat pan/latch mechanism which have been on the back burner.

I'm also planning on picking through the Carbs in the coming months, I'm sure I'll have questions, and I'll try and take lots of pics on the way through. 

Thanks to everyone for all kind words, and help!

Also @beemerbum, sorry I referred to you as beerbum in my reply upthread.  Freudian slip eh?  :-)

[calj737]

A couple of things:

Your forks - the axle clamps have a "front and back" to them. Make sure the "gap" when clamped over the axle is to the rear of the bike.

Harness - I should have mentioned this in our earlier exchanges. It is my practice and strongest recommendation to use a more stock Honda color scheme and ignore the MG M-button colors. For instance, your head light LO from M-unit really should be WHITE. Turn L is ORANGE, Turn R is BLUE. Head light HI is BLUE. GROUNDS are always solid GREEN. And so on.

From the AUX multi connector, run each branch with the stock service color. Use BLACK for ignition coils (or unravel your stock harness and grab BLKT/WHT) use BROWN or BRN/WHT for your tail light, and BRN/WHT or BROWN for gauge lighting. This will make it far easier for you in the future, or some future owner to refer to the stock diagram and make sense of your harness. I often scavenge the stock harness for the special colors (YLL/RED, BL/RED, GRN/RED etc) to at least make pigtails near the component. Makes troubleshooting a breeze.

Harness splices and connectors - Skip the WeatherPaks. Yes, they're really nice, but they're really bulky. Instead, I use Molex connectors. You can use the smaller gauge connectors too as you're dealing with smaller wire. All these "plastic gang connectors" essentially function the same way with a Male and Female side. The crimped connector itself is held in the housing with a small barb. Depress the barb, remove the wire. Easy. They make M/F connectors in spade, round (bullet) and either works. Check out www.molex.com for a complete inventory, then search the web for a reseller.

As for associating wires together for serviceability, I typically use a connector for the L side of the backbone, and one for the  R side. These are "service" looms and are carrying power to components. Realize, the only connection you have from your controls is the M-Button, so to disconnect a handlebar control is really simple.

I like to use rivet nuts installed in the frame for grounds, and retainer loops. It allows me to move everything out of the headlight except the H4 plug. Having grounds hit the frame beyond the steering head is also beneficial as no current passes through the steering bearings (grease). You can use the aluminum nuts, and stainless pan head socket screws and get a very clean install and have excellent connections. Here's 2 pictures as examples. The first shows the retainers organizing the looms, and the second is an under the seat view of a build. Notice the ground screws (green solid wires) in the side rails. That's what I'm describing.

Your bike has room below the tank for you to run the looms. Just be mindful not to locate all your Molex connectors in a concentrated area as it will effect the tank fitting. And you can create "jumpers" in the Molex connector to simplify your runs. Say you're using a 3-way plug, and need 3 BLACKs from AUX. Run a single feed to the Molex, then crimp a short leg to another spade, and repeat. This way, AUX sends power to all 3 circuits at once, and on the other side, you can split the service feeds to wherever they need to go (Lights, Gauges, Coils, etc).

Okay, enough babble. Get this thing built! (And wired  )

[Mule169]

<newb>

Harness splices and connectors - Skip the WeatherPaks. Yes, they're really nice, but they're really bulky. Instead, I use Molex connectors. You can use the smaller gauge connectors too as you're dealing with smaller wire. All these "plastic gang connectors" essentially function the same way with a Male and Female side.

Even for the bigger gauge wires?  Most of the Molex stuff I find online is 18-22 AWG?  I guess I'm thinking it would be rad to have all one type of connector (I.E. replace the stock harness connectors where tying into new harness).  Molex jobbies beefy enough for ignition coil, reg/rec, alternator wires?

</newb>

[calj737]

Yes, they have connectors even up to power transmission. You might need to buy different sizes for some wires, but 99% of what you'll connect is covered by 18awg

[Mule169]

Ok I didn't have as much time as I wanted to work on the bike this weekend.  My girlfriend took the Oregon class to get her endorsement (RAD), but that meant I had to watch the dog most of the weekend.  Did some basic layout of some components, got all of the electrical stuff unpacked and organized from shipping.  Might take a day off work, or an evening to really get things humming along this week.

So sort of a basic layout of batter/electronics as I see them




In between the two welded bars in the seat tray there you can see my hacked together precision engineers seat latch from a VFR, and the solenoid that will activate it. 

the idea is that my seat pan that has kind of a "false bottom" will mount on the posts, and latch to hide all the important bits.













So yeah, I have a few little things to sort out as far as mounting everything (thinking some high strength velcro for most of this stuff, and bolts for the reg/rec as it might get too hot and melt any adhesive based attachments), and I still have to knock some ideas around in my head. 

Hopefully more at the end of the week!

[greyghost18t]

I am looking forward to seeing this come together! Looks great so far

[SKTP]

You wiring looks beautiful — impressive stuff

[calj737]

For some reason, none of the pictures from your last post appear on any device I use to read your thread? Anyone else having problems?