Topic: Bruce - '73 CB500

[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.

[calj737]

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.

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.

[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.

[calj737]

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.

Reading plugs after you have been riding is pretty pointless as they will reflect AF mixture at all throttle positions. Better to start with fresh plugs and tune for IDLE, MID and WOT.

[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.