Topic: Bruce - '73 CB500

[bahia]

This is Bruce, my 1973 CB500. I just picked it up from a local guy here in Chula Vista (South San Diego).
No history on the bike. No clue how many miles. But it had a clean title, strong compression, and a big box of parts. The seller is a big CB750 collector/flipper. If I'm missing something he's nearby and cool.

Pics are of Bruce in his new home.
He'll be my first build, but not in a huge rush. My first order of business will be to get the carbs assembled and then attempt to get him started up to see if I need to do any engine work.

Wish me luck!
 

[bahia]

Yeah, I'm pretty certain of it. I do have plans to go to 4-1 on it.
In addition to running pretty bad, those straight pipes will likely piss off my neighbors too.

[Stev-o]

In addition to an exhaust system with back pressure, the intake also like the stock airbox, makes tuning a breeze.

Dont be tempted to buy cheap carb kits, they will cause issues. In fact, avoid all china parts for your Japanese bike!
If you have the OEM brass, just clean and reuse it and use new gaskets when rebuilding the carbs.

If this is your first SOHC, grab a beer and read the Carb FAQ...

http://forums.sohc4.net/index.php/topic,5410.0.html

Good luck

[bahia]

I forgot I started this thread... Well, I've got some catching up to do.
I called the bike Bruce after Bruce Lee. Early on I did a mockup (on a 400T I think) of the direction I wanted to go with the bike.
Pretty much just blacked out everything, while keeping the engine shiny and a reference to Bruce Lee's yellow jumpsuit on the tank.

[bahia]

The owner didn't have a ton of details on the bike when I bought it. He told me the forks weren't 500/550 forks, but couldn't tell me exactly what they were. I started to investigate so I can figure out what kind of calipers would fit, and as the good folk in the tech forum pointed out, there was nowhere to mount calipers on, and these were CB400T forks which used a drum.
So, on to Ebay I went hunting for some CB550 forks.

[bahia]

Last week, I finished up a pretty intense web development project that ran about 2 months. So I've just been out in the garage pretty much everyday getting the bike fixed up, and ready to run. I started with getting the carbs cleaned up and polished.

[bahia]

Getting the engine out was very challenging. I had to do all kinds of power yoga to get that block on the floor.

[bahia]

Valve cover off to make it shiny, and inspect the #3 plug hole I thought was stripped (thankfully it was not).

[bahia]

Ordered some yellow spray paint to match my helmet and Bruce Lee's jumpsuit. It'll go on the tank and a few detail ares on the bike. Tested it on the caliper, and it has too much orange in it compared to the helmet. Gotta find something more bright yellow.

[bahia]

Got Bruce disassembled all the way down to the frame! Woot!



New 550 forks sitting in the box, old ones leaning against the wall.
Gotta get those old ass tires off the rims. That'll be fun...


Oooh! A double rainbow!


Think I should get a new chain? LOLOL

[bahia]

Those tires were the WORST!!!
Should have gone on youtube before I did the first one. The trick I learned was to take a boxcutter to the sidewalls and pull off the treads before i used the tire spoons to pull the beads off. That was WAY easier.

[bahia]

Whoever owned this bike before I got it was a clown! Look at this kickstand they welded on.
Not only is it a joke, but it never locked in place, so half the time it felt like the bike would tip over.


Ready for surgery.


I'll be mailing this to a friend's husband and having him weld this to her Harley. 


Ahh, nice and clean and ready for a TC Bros kickstand.


Gotta do some cleanup, but tabs are gone, and the rear is ready for the hoop. A neighbor is bringing his welder over tomorrow.

[Stev-o]

FYI - the simplest way to remove/install the engine is the "lay it on it's side" method. Use a heavy duty moving blanket or two.

That kickstand is a joke!

[SOHC4 Cafe Racer Fan]

You may want to grind down the inner lip of the lower rear engine frame mount.  This sometimes catches the engine when removing or installing.  I would definitely recommend the lay the frame over the engine on its side method, which Stev-o recommended.  So when you start assembly, just start with the engine on its side and the bare frame laid over it.

[bahia]

FYI - the simplest way to remove/install the engine is the "lay it on it's side" method. Use a heavy duty moving blanket or two.

That kickstand is a joke!

Yeah, I tried that trick. Because I had the front and rear wheels still on, I think that made things a bit more challenging. Fortunately it's been stripped down since. So hopefully putting it back in won't be as much of a struggle.

[bahia]

I hired a designer on Fiverr to come up with a better design than the one I came up with (mockup photo above), and this is the design that he came up with. I'm so stoked, and can't wait to see this in real life on the tank! (The yellow is obviously not the right yellow).

[chiefum]

That looks awesome!

[SOHC4 Cafe Racer Fan]

Be like water.

[bahia]

Welding day!
Had to weld the battery box, and seat hoop. I was going to weld on a kickstand, but I bought a TC Bros (which as it turns out is for Bobbers), and looks way too short. Got to figure that out the kickstand situation.

As far as welds, I practiced a fair amount last night and this morning. But when was game time, my welds were poop. I'll grind them down tomorrow, and see if I need to fix. Hopefully it will be strong enough to stick a chick on the back without structural frame failure.

[bahia]

Printed out the design to get an idea of the right size. Think I need to go bigger.







I fabricated my first ever pieces from steel. The little tabs for the seat, and the end pieces to where I chopped the frame to make way for the hoop.
In many of the builds I've seen, people leave this open, which I think is poor craftsmanship. And I doubt it's good to leave the inner tubing exposed.

Despite my appreciation for craftsmanship, my welding was absolute dog #$%*, and resulted in lots of grinding.

During said grinding, I removed a chunk of skin with my grinder's flap-disc while spinning at 12,000rpm. It's a small chunk, but you can see my metacarpal bone.
...I'll spare you photos of that.







I decided instead of putting my skin in danger any more today, to put my lungs in danger and break out the polyester resin and fiberglass.
Just kidding... I have a respirator!
I do my own surfboard ding repair, so I already have a bunch of glass and resin in the garage. Had just enough to lay down 4 layers of what I think is 8oz fiberglass. Seemed like some random boat glass I had laying around for some reason. It was way too heavy for a surfboard, (well any board made after the 60s).
I'll likely get a custom leather job done in one of the Mexican upholstery shops near me (I live in south San Diego, about 5 minutes from the border). I figure this will work for a decent seat pan.

[XC204]

Hey that's looking good and fast progress! I've got my own 73 cb500 that I started 8 years ago and am getting near the home stretch. Good luck and keep posting.
Gary

[bahia]

Hey that's looking good and fast progress! I've got my own 73 cb500 that I started 8 years ago and am getting near the home stretch. Good luck and keep posting.
Gary

Thanks! I've got a couple weeks of downtime, so I am trying to get as much done in the time I have. I hope to have it close to finished next week. We'll see how that goes!
Do you have a thread running for your bike? Would love to see another '73 500.

[SOHC4 Cafe Racer Fan]

So, why Bruce Lee?  Just curious.  One could say, "Why not?"

[bahia]

So, why Bruce Lee?  Just curious.  One could say, "Why not?"

My 2003 Xterra is named Steve McQueen. Figured I'd keep the great actor theme going.
When I pick up a late 90s Ducati Monster, I'll likely caller her Sofia Loren. 

[XC204]

Bahia if have a project thread it's cm 500 "Free"  style it's a few posts below yours.
Gary

[bahia]

It's been a couple weeks, mostly late nights and hard work, but there was a few days I was bed-ridden after trying to break my back at the BMX park.
So, let's get caught up!
Finished the seat pan, it's currently at the leather upholster getting done up. I picked out the leather, and it'll have 2" of good foam. Can't wait to pick it up.

I haven't seen too many seats that come up smoothly onto the tank line, part of the reason I decided to do my own. Took a little tape, more fiberglass, and lots of dust from sanding and grinding.

[bahia]

...and on to painting.
Well, before that, lots and lots and lots of wire wheeling.

Considering how much I've spent on primer, paint, and clear, and how much time it's taken to prep and clean the metal... I'm most definitely taking my next project to a powder coater. Sandblasting would do a far better job than I could with the grinder. Plus the powder would get into the nooks and crannies much cleaner than the rattle-can can.

As far as rattlecan jobs go, it turned out pretty decent. 1 coat self-etching primer, 1 coat normal primer, 3 coats engine enamel, 2 coats clear.

 

[bahia]

Just picked up the seat from the upholsterer today. I picked out the leather, and I'm so stoked to see it complete that line of the tank.
I'm beyond happy with the leather choice, and the job my guy did.

On the flip side, I did a compression test and got some poor results. I'm now considering a teardown and rebuild...
Readings were:
C1: 85 psi
C2: 55 psi
C3: 80 psi
C4: 85 psi

Here's some pictures of the seat to make me happy again.

[Stev-o]

On the flip side, I did a compression test and got some poor results. I'm now considering a teardown and rebuild...
Readings were:
C1: 85 psi
C2: 55 psi
C3: 80 psi
C4: 85 psi

I'd be concerned about #2, did you have throttle wide open?

I prefer leak down tests

[bahia]

Bruce is finally roadworthy!
Took quite a while figuring out my air/fuel issues. Came down to leaky boots and intake manifold.
I'm sure there's more tuning to do. Can't get going more than 50MPH.
Some engine case oil leaks, mount the reg/rec permanently, paint the tank, install a side stand, a few other things...
Oh yeah, I gotta register it as operational and get a license plate. 

The ride was pretty stiff. The rear springs were sized for my weight, but I might need to get some softer ones.
The wheels aren't balanced yet which might have something to do with the ride as well. Need to get some balance beads.
 

[SOHC4 Cafe Racer Fan]

You should be able to near double that when you get it tuned.  Have you run a compression test? 

I wouldn't use balance beads.  You can balance the wheels with adhesive weights.  I would not ride that bike in anger without the wheels balanced - especially on those Firestone tires. 

[rb550four]

  Hi , I just caught up with this thread again. I read it once before when you were polishing the caps and float bowls and gave it some time to see your progress, caught up with you at the lake with a bike that you think is road worthy that can't get over 50mph, poor compression test on one cylinder, no tires balanced, and the air screws have been giving you a hard time.
  Now I want you to understand that I am not trying to be disrespectful to you in any way, if fact , I  respect riders who want to build their machine the way they want to, but safety and the well being of that ride and rider really concerns me. Both can be lost in the same instant from things overlooked and I would like to help you find direction with this ride since right now it's not working right and you aren't happy with anything but the seat.
That being said . I would like to  talk about some things on this thread that I see are missing that may help you to get this machine where you might want it to be. Otherwise you will be disinterested in it soon and end up getting rid of it
 The carb clean up . carbs need to be perfectly clean on the inside more that polished on the outside in order to run correctly. didn't see any evidence that the carbs have been truly cleaned.  That is always a problem and sounds like a big part of your bike's problem, the other part is that anyone who puts on pods and a new exhaust will ask others what jets would run better in that application, especially newbs you didn't ask. And do you have any idea if those carbs are in sync?  Q. are any of the pipes cold  and what's the plugs look like.
  Compression - have you set the valves? that low compression could be from a valve not seating correctly..burnt,bent valve or broken spring, guide issues, seal issues,or seal lost by other internal damage. Or could be a broken ring, cylinder wall issue, or head gasket.
  I think that you may need to order complete top end gaskets for the work that will be coming after you clean and sync those carbs, set those valves and check the ignition timing and find no improvement .But until then it's fuel , air  and spark, proper amounts of each, at the right time.Don't forget to use your shop manual, the information you need is in there. If you don't get it , ask someone here about it, no shame in that, most folks are only too happy to help.
 

[bahia]

I wouldn't use balance beads.  You can balance the wheels with adhesive weights.  I would not ride that bike in anger without the wheels balanced - especially on those Firestone tires.

Have you used them? This guy has. And he said the bike was more stable than conventional weights.
http://forums.sohc4.net/index.php/topic,98988.msg1104702.html#msg1104702

  Hi , I just caught up with this thread again....

There was a lot of work (including much of what you suggested) done that wasn't documented. I'll post that when I have some time. But, yes, the top end was rebuilt, valves lapped, carbs were cleaned, bench synced, quite a bit more.
Maybe later this week I'll sit down and start posting the photos.

[rb550four]

   Excellent! I was pretty worried for you and thought we could help.

[bahia]

   Excellent! I was pretty worried for you and thought we could help.

I appreciate the concern. I still do need to figure out what's contributing to the lack of power at higher speeds. I suspect it might be low compression. I have some leaks between the head and the jugs which might be the source. Gaskets are new, so I think I'll triple check the torque specs on the bolts.
Carbs are bench synced, and doubt a vacuum sync will make up the missing 50mph (but should do it anyway).
Main jet is 115, with the K&N pods this should be pretty ballpark.I haven't started plug chopping yet, so we'll see.

[Shtonecb500]

You did a good job with your seat pan, the leather turned out nice. You should really break into that motor and you should definitely just take it to powder coat next time. You will be beyond satisfied with the end results.

[bahia]

105 is what you want. Probably move the needle to a one position more rich from stock. At 115, you’re choking the motor. If your compression is low, you’re creating less vacuum and that coupled with too much fuel, the motor is drowning.

Maybe this weekend I'll drop them down to the stock 100s I have and see if that helps any. I'll have a look at the plugs too.
Needle was moved to 3rd notch (one notch richer than stock) as per K&N's recommendation.

You did a good job with your seat pan, the leather turned out nice. You should really break into that motor and you should defiantly just take it to powder coat next time. You will be beyond satisfied with the end results.

Thanks! Yes, the seat did turn out very nice. Very happy with that.
But you're right. I should've done the powder coat thing. But at least I can touch up all the nicks in the paint job.

[RAFster122s]

You don't read well between the lines do you? You insulted Sohc4 cafe racer and maybe RB as well...
and I am surprised Calj is being patient with you and offering you advice still. You attacked RB and insulted him. You likely do not see the tone and arrogance that can be read in your reply. Basically came across as I know what I am doing...I don't really need your help.

Good luck to you just thought we could help...

   Excellent! I was pretty worried for you and thought we could help.

I appreciate the concern. I still do need to figure out what's contributing to the lack of power at higher speeds. I suspect it might be low compression. I have some leaks between the head and the jugs which might be the source. Gaskets are new, so I think I'll triple check the torque specs on the bolts.
Carbs are bench synced, and doubt a vacuum sync will make up the missing 50mph (but should do it anyway).
Main jet is 115, with the K&N pods this should be pretty ballpark.I haven't started plug chopping yet, so we'll see.