Topic: 72 CB500 Restomod - *Update* Sold!

[Scramps]

I've got a flat washer, lock washer, and a little dab of blue loctite on each one. I think it's gonna be okay.

Fashioned myself a little temporary fuel supply and did some more tuning this morning. I don't think that my DIY carb synchronizing tool is super reliable, since it probably isn't making a perfect seal, but all 4 carbs are peaking at ~15 in/Hg at idle with the bike warmed up. Borrowed my friend's timing light again and adjusted the ignition plate back to the correct position. It had moved when I replaced the screws.

I'm having a hard time getting it to start and idle. It's definitely made worse by the cold, but it's always been a little difficult to fire up and I've always had to mess with the idle screw to keep it running. To recap:
- Valve timing is set to shop manual specs
- Pamco ignition kit installed (new coils, new wires, new plugs, new caps) and set with timing light
- Carburetors have stock jetting (genuine keihin parts, no aftermarket jets), everything has been thoroughly cleaned, multiple times.
- Stock airbox installed with new air filter.

The only item that I have any concern about is my floats, which are set to keep everything slightly lower than the tops of the bowls, but they will leak from the overflow tubes if I leave the fuel valve open while the bike is parked (Yes, it's the dreaded fuel leak that I've seen on the forums several times before) I suspected that it was #3 that was doing this, so I replaced that float needle, cleaned the port, and set that float to the same height as the rest, but it still happens.

What do you reckon?

[RAFster122s]

I hate to recommend it but did the seat and the float needle get replaced or just float needle?  I am thinking a good exam of #3 seat is in order and that requires a good strong light, magnifying glass and the carbs to be on the bench. Might be able to check it out with one of the endoscopes you attach to a cell phone camera.

I would suspect the #3 float bowl overflow tube has a leak or crack.

Back to baking a cheesecake for class party tonight...

[RAFster122s]

Cal, was it on the 500 or 550 you had to go through again? I like to use a bit of Seafoam in every tank...it seems to help lessen fiddling with the carbs on the CX and I don't know yet on the cb as the cam cover problem stopped me from pursuing getting it going as it had too much wear in the cover. Wondering what kind of motorcycle art to make from the old one...

Has your son continued to be too tied up with school and life to do anything more on that design and build?

Are you getting hit with a lot of rain like Philly area and N and NE are this weekend? Temps are nice here but roads are still salty from last weekend's foot of snow we saw.
How much snow the Richmond area see?

Scramps, hope Cal's advice helps you get it sorted to run better. Something is different on #3 it sounds like. See if the float is moving freely too. I have experienced a float bowl gasket that was not factory fowling the float's free movement with the bowl on. You should be able to easily see if that is happening when you examine the bowl gasket.
There are a lot of variables possible for a carb to not act like its mates. Bench sync and vac sync as Cal recommends. I would not play with the idle screws if I could help it. You end up introducing constant change when you do.  If choke is not helping you have jetting issues for normal operation.

I keep learning or try to...

[Scramps]

Luckily, ~2000 rpm was where the bike wanted to idle while I was syncing, so that's nice.

If my overflow tube is cracked, is it possible to repair or will I just have to get a new bowl?

I guess I'm expecting too much of my bike when I'm trying to start it cold. It sounds like I just need to be more patient with it.

As for the weather here, I'm not sure how it looked in Richmond, but here in Radford we had about 16" and drifts that were well over 2' in some spots. It's almost gone now, though.

[RAFster122s]

If you can get them clean you can solder them. Torch works well as long as you don't roast the carb bowl melting the alloy they used. Flux helps...not acid core flux or solder though. Plastic float isn't leaking, right? That can really throw wrenches into the works.  But clear tube test when running with long tube tied off to higher point can allow you to see the level when that carb is being a pain.
As long as the overflow line doesn't pop off its nipple or your drain screw clear tube/ line pop out of the drain port it is OK for testing purposes. You can route your overflow lines into a clear coke bottle zip tied in place with clear lines on overflow so you know the offending carb and can see the volume.

Ever try rapping the fuel bowl with a screwdriver handle to see if the float is sticking or needle is hanging up when it is puking fuel out the overflow?


Very little left here now, it was brutally heavy snow here...very wet. Weatherman reported our foot of snow was equivalent to 1.5" of rain.


If it is a cracked overflow and cannot be repaired talk to member harisuluv, he does carb work on our vintage carbs and has lots of spare parts usually.  He is a great guy and at one point he was doing caliper bleeder repairs too.

[Scramps]

Haven't taken the time to really dig into these tests yet. I did the clear tube test a while back, #3 was not filling up, but the new float needle seemed to take care of that, although I don't remember how I came to that conclusion.

I need to check some of the other things that you mentioned. I like the idea with the bottle on the overflow tube, I don't know why I didn't think of that before. I was assuming it was #3 because it was wet, but I never actually verified anything.

I really don't like handling gasoline, but it's part of the job I reckon.

[RAFster122s]

Haven't taken the time to really dig into these tests yet. I did the clear tube test a while back, #3 was not filling up, but the new float needle seemed to take care of that, although I don't remember how I came to that conclusion.

I need to check some of the other things that you mentioned. I like the idea with the bottle on the overflow tube, I don't know why I didn't think of that before. I was assuming it was #3 because it was wet, but I never actually verified anything.

I really don't like handling gasoline, but it's part of the job I reckon.

Not as much fun as handling dynamite but it is more explosive than dynamite today...more energy in gas.
Wear nitrile gloves, they will protect your skin from smelling like gas for a day or more...


A bit of colored tape near the end of the tube can give you visual on what is what or stripe them with a sharpie...that will last until they are immersed in the gas.


David

[Scramps]

I have identified the perpetrator, it was #1 the whole time! *GASP*

Anyway, it's weird; turn the fuel valve on, wait about 10 minutes (which seems waaaay longer than it should take to fill the bowl, but moving on) it dumps out about 1/2 ounce of fuel, give or take, then it just stops.

I only got to observe it once, then I had to leave, so I turned off the fuel valve.

My inclination here would be a sticky float, so I'm gonna try and fix it in situ if possible

[RAFster122s]

Congrats on ID'ing the perp...now smack him/it around until it falls in line...
hehe

I'm sure you will be able to sort it out and get it purring...

David

[Scramps]

Still haven’t done anything with the leaky carburetor, or anything on the bike for a couple weeks really.

Ever since I put the OE clutch pushrod, I can’t get the clutch to release. I’ve tried a few orientations of the adjustment points, but I can’t seem to be able to figure out how to achieve full slack and then tighten things up from there.

The shop manual isn’t very helpful, and I can’t find anything on the forums that gets into this specific thing

[Gurp]

Clutxh spring bolts too tight? With older bikes I've ran into this a few times. Ive even been the culprit a few times as torque wrenches are not as accurate near the edges of their scale.

[Scramps]

That’s possible, I did put the stock springs back in - I had been using the springs from the 550 which are a good bit taller. With those installed, the oe pushrod wouldn’t even fit. The PO had added some washers to the original springs, but they were also running a pushrod that was way too short. So I thought the parts manual configuration would be appropriate for the stock pushrod

[Gurp]

Ive found as the parts where in sometimes you need a 1 or 2 +/-  the torque the manual recomends. My 500 was not releasing at factory torque. I dropped 2lbs and it worked fine.

[Gurp]

I definitely need a better torque wrench. Building a better tool set a few bucks here and a few bucks there.

[Scramps]

Finally got back into the garage today, clutch is working now. I have the adjusters at the ends of the clutch cable both backed out as far as they can go, and the slot on the left side cover for the actuator is counterclockwise from the level mark about 1/8”. It seems less than ideal, but if it works, etc.
Also, I’ve left my fuel valve open while I go run some errands, but I think I’ve gotten that part sorted as well. There was a tiny piece of purple plastic in the needle valve’s bronze inlet port keeping it from being able to close.

Still waiting for paint. Really looking forward to seeing what it looks like

[Gurp]

What color are you goong Scramps?

[Scramps]

That’s the template I gave them. It’s Electric Gold and white

[Gurp]

Nice.

[Scramps]

Still no news on the paint, but I do have a shiny new replica gas cap to slap on there when the time comes



I was attempting to sand down my old one to get the pitting out and give it a nice brushed nickel look, but these old caps are tough!

The replica isn’t 100% identical. The sides are vertical rather than tapered, and the corners are sharper, but it seems solid enough.

[Gurp]

Get everything back from paint yet?

[Scramps]

Nah, I’ve been calling them once every week or so, keep getting the same answer. “We’re really busy, but we’ll get to it as soon as we can”

I can’t complain, the people that run that shop are practically family

[Gurp]

Can't wait to see them when they are done.

[Scramps]

News!







Still waiting on the side covers. The plastic they’re molded from wasn’t taking paint very well. Needed some glazing, or something along those lines. Also decided to scrap the stripes on the side covers. We laid it out and it just looked weird.

[Scramps]

Headlight bucket rat’s nest: eliminated

[Gurp]

clean!