Author Topic: Pin2Hot's 73 CB750 (Read 56288 times)

Pin2Hot · « **Reply #200 on:** March 05, 2018, 06:45:02 AM »

Ok, remind me to never do pie cuts for a frame hoop . . . after 4 hours of tedious, out-of-position welding, the frame is welded out. The quality ain't all that great but I spent a lot of time on the welds that matter most. The patterns I made for the seat still fit which tells me it didn't move all that much during welding which is promising.

I welded on the battery box bracket and mounted the box itself. On the box is the main starter solenoid (incorrectly mounted upside down in the photo). It's a neat unit, got it from Revival Cycles and am using it because it works very well with the m-Unit. It has the main fuse and spot for a spare integrated into the starter solenoid. It also has a connector for supplying fused power to the m-unit itself as well as the aux power:

Lots of welds:

One of the big mental holds-ups I've had on this project was how to get the right satin finish I want on all of the aluminum throughout the bike. Watching jafromobile's videos on YouTube have been super helpful in many areas but in aluminum prep specifically. His whole series on porting / polishing heads (

pointed me to dremel buffing wheels. I bought two of these from amazon: https://www.amazon.com/gp/product/B010NLHCOW and was able to get my rear wheel hub and brake carrier polished just the way I wanted.

This photo doesn't actually show the satin finish (derp) but shows that I finally got the rear wheel finished:

I realized while doing the rear wheel that I had messed up the spacers. There's a collar that fits between the sprocket carrier and cush drive that I was using on the OUTside of the sprocket carrier instead of between the carrier and cush drive. This changed the spacing and forced me to make a new spacer. Fortunately I had the material laying around to do that but I'm pretty sure once it gets fully assembled, I'll be modifying them again to get my chain to line up perfectly again.

I've crossed another mental barrier having the frame welded out, it certainly feels much more finished. When banging it around, the frame "rings" like it used to instead of buzzing like a bin of rusty parts. I'll be working on the seat next so a bit of woodwork and upholstery is coming up. Thanks for reading!

DurangoCB · « **Reply #201 on:** March 05, 2018, 07:14:15 AM »

Hey, chalk it up to lots and lots of welding practice.

I recently bought a set of those Dremel abrasive polishing wheels and was disappointed by how quickly they disintegrate. They do work well, though.

calj737 · « **Reply #202 on:** March 05, 2018, 08:25:30 AM »

Pinhot - “next time” instead welding out of position, “bump weld it”. One thing about TIG, is there’s no issue with multiple starts and stops. Bump welding is what guys do with anodized tubing, but it works equally well with steel and aluminum.

Essentially, you are making connected “tacks”. Set your heat to full (60-70 amps probably on your tubing), full pedal, dab, off the pedal. Advance your torch to the leading edge of the puddle, blast the pedal and dab, off the pedal. Rinse and repeat until you complete the circumference. This allows you to reposition for each tack, and get straight and square without fighting feed, torch angle, arc length etc.

Here’s an example in aluminum tubing so you can see the ripples become very consistent.

calj737 · « **Reply #203 on:** March 05, 2018, 08:39:21 AM »

And some 1” 0.063 with 1/16” er70...

Pin2Hot · « **Reply #204 on:** March 05, 2018, 09:27:31 AM »

Quote from: DurangoCB on March 05, 2018, 07:14:15 AM

Hey, chalk it up to lots and lots of welding practice.

I recently bought a set of those Dremel abrasive polishing wheels and was disappointed by how quickly they disintegrate. They do work well, though.

Yeah they burn out pretty quickly especially if the surface is rough to begin with which I guess makes a lot of sense. Getting 40 of them for $11 bucks from that amazon link makes it seems a bit easier to deal with their durability. Sure as hell beats beating up your fingers trying to get into a tight spot with 120 grit paper.

Pin2Hot · « **Reply #205 on:** March 05, 2018, 09:37:33 AM »

Quote from: calj737 on March 05, 2018, 08:39:21 AM

And some 1” 0.063 with 1/16” er70...

Great stuff, Cal. I'll try that next time. And there WILL be a next time despite what my wife says. Please don't tell her I said that...

calj737 · « **Reply #206 on:** March 05, 2018, 10:46:38 AM »

You can wash those welds in now, Pin. Use the same technique I described, no filler. Bump your amps to 75. Just hit the weld full amps, then kill the arc. Move the torch, rinse and repeat. It will drive the weld in, flatten them out, and reduce your grinding to clean them up. Plus it will let you practice the technique

Pin2Hot · « **Reply #207 on:** March 05, 2018, 02:19:28 PM »

That's cool, I can use the fancy button on my torch to go full blast and wash it in. I'll give it a whirl.

Shtonecb500 · « **Reply #208 on:** March 05, 2018, 04:39:26 PM »

I have the same kind of airbox for my 550, that one period correct, right?

Are you going to keep that airbox?

Pin2Hot · « **Reply #209 on:** March 05, 2018, 06:16:32 PM »

Quote from: Shtonecb500 on March 05, 2018, 04:39:26 PM

I have the same kind of airbox for my 550, that one period correct, right?

Are you going to keep that airbox?

Well, not sure yet really. I think I'm gonna run with it and see how well it works. I've heard people either love or hate these things. I actually had to make it a bit skinnier to a work with the monoshock so not sure how much that's going to impact how well it runs. Do you have any experience with them?

Pin2Hot · « **Reply #210 on:** March 09, 2018, 07:13:01 AM »

Guys. A miracle occurred in the garage last night. For the first time on this project, a solution to a big problem solved itself. I've been struggling to find a solution to actuate the rear brake on this bike. To make routing easier, I decided to use a rear brake cable conversion kit from Dime City Cycles (https://www.dimecitycycles.com/dcc-customs-rear-brake-cable-conversion-kit.html).

The problem I faced was finding a suitable place to mount the front cable stay without welding on some ridiculous looking tab to the frame. Then I saw it: the 2000 CB929 rearsets I'm using have a threaded hole on the back side of them for what I think was the rear brake cylinder mount. All I had to do was drill a hole next to it for a small post on the cable stay that I think prevents it from rotating. I just found it pretty crazy that a modified 73 frame, running a 1980 DOHC swingarm, 2000 929 rearsets and a custom cable bracket all magically worked out.

The front cable stay bracket attached to the back of the rearset:

Still a bit of work to do here such as shortening the arm used to keep the drum in place but the cable will be routed up and fixed to the swingarm itself:

Looking backwards. The original rear brake shaft arm will be modified for this application. I need to build out a linkage system on the brake pedal which I'll detail soon.

DurangoCB · « **Reply #211 on:** March 09, 2018, 08:39:19 AM »

It's nice when that happens! Though I don't think all the credit goes to the rear sets nor to Luck... 9 out of 10 people wouldn't have the eyes to recognize that there was a solution to be had there.

Pin2Hot · « **Reply #212 on:** March 26, 2018, 06:22:20 AM »

I've spent a lot of time lately figuring out the rear brake. A lot of slicing and dicing has occurred to get me to this point, mostly by breathing new life into old unused parts from the tear down. And like everything else on this bike, it's taken a LOT longer than I imagined just getting the damn rear brake working. Although, I'm very happy with the function of it even though I still need to make the linkage to truly make it work.

If there are any cycling enthusiasts out there, I did a flop and chop on the rear brake pedal arm as well as the pedal itself to make the rearset linkage operate in the correct direction. OEM parts ready to get hacked apart:

Lever arm shortened, rear pedal hacked up:

Drum brake arm chopped up to make it straight as opposed to off-set:

New brake arms all welded up:

New straight drum brake arm:

Brake linkage all lined up. Notice my "oh-#$%*" spacer as I didn't shorten the arm enough, it ended up working out OK though. Also, don't get used to that cable stay bracket...

Ok, so I'm embarrassed by this part. Just know that it works and I'll make it prettier later. What I thought was a gift from the fabrication gods ended up not working. I had to modify that cable stay for a billion different reasons so this is the solution for now.

I still have yet to weld on the actual rear-set pedal arm and figure out the linkage but I think that's going to be somewhat straight forward. Definitely a lot easier than this damn thing.../.,amsdsdfl;kasdjdf

Pin2Hot · « **Reply #213 on:** March 29, 2018, 06:26:41 AM »

I'm turnin right!

DurangoCB · « **Reply #214 on:** March 29, 2018, 07:45:05 AM »

Now that looks tidy! Nice work. Can you give links to those lights? And did you fab the brackets or just pick them up online?

Really looks nice.

Pin2Hot · « **Reply #215 on:** March 29, 2018, 09:04:25 AM »

Thanks dude. They're these cheap little things:

https://revivalcycles.com/collections/for-your-ride-bestsellers/products/led-light

Pretty sure it was this tab: https://www.aa-mfg.com/shock-tab-2295 Since these were for a larger tube diameter, I had to grind it a bit to make them fit a bit better.

PS these lights a BRIIIIIIGHT. That battery I was using was almost totally dead and they were blinding. At least people will know I'm turning!

Pin2Hot · « **Reply #216 on:** April 23, 2018, 06:51:10 AM »

As is tradition in my garage, the previous month has been spent standing in silence, staring at the frame second guessing everything I've ever done to his project. SO, in true form, hardly anything has been done. I spent two weeks worrying about if things are truly square or how much did the welding draw the hoop to one side? Is it noticeable? Am I going insane? I should just give up.

I have not given up. I started to work on the seat "pan". I'm trying to lay out the supports for the pan which will also serve as the mounting points for the regulator/rectifier and mUnit. The pan is two layers of this bendy plywood my brother had in his shop which will be laid between the frame rails and curved into place. A few layers of walnut veneer will go on top/bottom. There will probably be a single layer of e-glass fiber on the bottom to waterproof it. On top, a skinny padded area will sit atop the pan made from 5/8" gel material, covered in suede with some fancy stitching.

Here's the pan being fitted:

So that's the extend of the work. In one month.... To help me get over my lack of progress, I took a functioning bike and made it non-functional. Ya know, to knock something else down a peg or two. Actually, I've been neglecting my poor little Ruckus for quite some time now and decided to give it a good makeover. New cables, new jets, new drum brakes. Basically all the consumables on the bike are being replaced. And good thing too. As I was pulling the carb off, the throttle cable broke on its own so I'm glad I did that now before I got stranded somewhere.

Two non-functional machines:

Ruckus carb:

Funny comparison: CB750 vs. Ruckus forks.

"Clean" Ruckus:

This week will be spent waiting for parts for Scoots so I can get it out of the garage. After that, I'll weld in the seat pan supports and get the frame blasted and primed. I'm hoping things accelerate after I get the seat figured out because that's truly the second to last big issue on the bike. The final issue will be the headlight mounting. Not looking forward to that one...

DurangoCB · « **Reply #217 on:** April 23, 2018, 08:30:26 AM »

I had a similar weekend- I could feel my project eddying out at the most dangerous point so I sacked up and starting knocking a few things out to get over the hump.

That Ruckus has a 2-bolt bicycle stem. LOL

Keep at it amigo!

Pin2Hot · « **Reply #218 on:** April 23, 2018, 08:54:10 AM »

Quote from: DurangoCB on April 23, 2018, 08:30:26 AM

That Ruckus has a 2-bolt bicycle stem. LOL

Ha yes it does! It's held up incredibly well. I mean, as manly as one can be riding a Ruckus, the stock handlebars forced you to look like a total nerd. So the pegs and lowered bars were the solution. Now I only look like half a nerd cruising around at 32 mph.

I can certainly see the light at the end of the tunnel on the big bike. I think getting the parts blasted and primed will be a shot in the arm to take it across the line.

Pin2Hot · « **Reply #219 on:** April 26, 2018, 06:33:26 AM »

Hey some work on the actual project! I spent the past few nights making a pattern for the seat pan. I had never really intended to use a full seat pan for this bike but instead use a few struts that stretched across the frame hoop to mount the mUnit, reg/rec and the seat itself. Using a seat pan has made it easier to keep the seat itself nice and centered within the frame rails AND prevents any water from splashing up on my butt. It also will probably look much nicer.

Holding it in place:

It's 16 gauge steel so I was able to bend it into position pretty easily. With the help of some duct tape of course:

Failed tack and crappy braze tacks. I tacked with silicon bronze because it's easier but will come back and stitch it into place with regular 70S.

Welding in sandals. Ended up looking pretty straight!

I'll weld it out tonight, put the turn signal tabs back on and then I think I can call the frame complete. Pretty neat.

Pin2Hot · « **Reply #220 on:** April 27, 2018, 06:53:14 AM »

Quick update: seat pan secured in place and the seat itself is being fitted. The plan is to sandwich these two pieces of flexible plywood with some walnut veneer to make it look purty. On top of that will sit a 1/4" plywood base with a 5/8" gel seat. The shape is roughly shown by the blue sharpie marks on the top of the seat. I'm planning on gluing it up this week. Still have to re-weld the signal tabs back on.

Bronze caterpillars:

Top:

Bendy:

Profile:

Pin2Hot · « **Reply #221 on:** April 30, 2018, 06:41:06 AM »

I came across something interesting in my nightly YouTubing:

Take a look at the second photo thrown down in the video, looks familiar...

I think it's safe to say that the maker of this kit cruises this thread (hello!). Anyone use this kit? Seems pretty slick and well made. It definitely solves the problem of relocating the oil tank and looks good, keeps things nice and low.

calj737 · « **Reply #222 on:** April 30, 2018, 06:46:33 AM »

There's 2 members who have ordered it. 63ssragtop is using it on a chopper-esque build (I think) and Rob (voxonda I think) is early stages in a race bike eval. Cruise the HiPo forum for Rob's progress.

algophobe · « **Reply #223 on:** April 30, 2018, 08:05:03 AM »

aw man, I coulda used it for my project. I really haven't looked into it but where does the cb550 place its oil reserve? I've seen cb550 builds and oil tanks are nowhere to be found.

btw. nice work on the bike so far. I welded my tray onto the frame itself as well. but some have advised that it would have been better to weld mounting tabs and attach the trays that way. not sure of what the pros here inputs on that.

Pin2Hot · « **Reply #224 on:** April 30, 2018, 09:30:25 AM »

I'm not very familiar with the 550 but I would imagine the oil is stored in the bottom of the engine for a wet sump set up. Cal or Durango know that bike better.

Yeah the seat pan for me doesn't serve much purpose to be removable. The seat itself will be detachable from the pan as well as the reg/rec and mUnit. So it's more of a mounting point for other things. It's all about what works for you.

Speaking of the seat, I spent a very frustrating weekend working on it. I made progress on the top, cushy part of the seat but have stalled on sewing the suede. SonofaB is it hard to work with. I like to consider myself a decent seamstress but trying to pin Alcantara and gettin it to curve is a huge pain. I gave up yesterday and tried to mow the lawn, only to have the lawn motor and weed eater fail to start. So I bought some bourbon and grilled shishkabobs instead.

Here's a sample of what the seat will look like in the end. My dad had some gorgeous walnut veneer that I'm going to glue to the bent plywood seat base and the cushy seat will be screwed to that. This is a sample of the stitching on the micro-suede set on top of the walnut:

Cutting the gel to fit the pattern, complete with Good Housekeeping: required for all things sewing related. I rubbed some corn starch on the gel to prevent it from sticking because it sticks to EVERYTHING. I found cutting it was easiest with a big chef's knife:

The 1/4" plywood base for the cushy part of the seat with the gel:

Layup of the layers that make up the cushy part of the seat:

The actual seat top, already top-stitched. This is what was giving so much trouble yesterday; trying to attach the 1 1/2" strip to the curved edge to make up the sides of the cusion.

News:

Author Topic: Pin2Hot's 73 CB750 (Read 56288 times)