Author Topic: '71 CB500 Four Scrambler (Read 23749 times)

DurangoCB · « **Reply #25 on:** February 25, 2018, 09:59:18 AM »

Thanks, Maui. I'm still torn. Primarily between paying for powder vs DIY paint. And between DIY (I'm addicted to learning new skills, sometimes to a fault) and just paying someone to paint/powder.

DurangoCB · « **Reply #26 on:** February 25, 2018, 11:06:04 AM »

Cleanup complete. I had good luck with just 90-120 minutes soaking in Pine Sol at room temp. The idle jets on the two worst carbs were stubborn, but I finally got them cleared out.

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DurangoCB · « **Reply #27 on:** February 25, 2018, 11:09:17 AM »

Can you bench test carbs for leaks? These carbs were such a #$%* to remove and I know installation is going to be twice as challenging. The thought of doing it one more time than I have to makes me cringe.

I find tons of info about bench syncing carbs but none for bench testing for leaks. Maybe because there’s no pressure in the fuel lines without the vacuum created by the engine.

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Stev-o · « **Reply #28 on:** February 25, 2018, 11:12:56 AM »

Yes, you can bench test the carbs for float function and float bowl leaks. Most guys don't do it though.
I have tested bowls as I did have one leak once on a K5.

DurangoCB · « **Reply #29 on:** February 25, 2018, 07:47:13 PM »

Thanks, Stev-o. Looks like this thread is just you and me. LOL

I was just searching for jetting@altitude tips and finally went through most of the Thoughts from Hondaman thread. Holy crap- what a wealth of info.

I noticed yesterday when I cleaned my carbs that someone has swapped the jets (stock main is 100, idle is 40... this bike has a 95/40) at some point. It has always lived in Colorado at around 5,500' so Hondaman's beta was spot-on (come down on the main jet by 1 for every 1,000' elevation where you live).

Drilling out the emulsion tubes now interests me but I'm a little intimidated by such tiny numbers, i.e. .040

Parking this here for my own future reference: http://forums.sohc4.net/index.php?topic=92347.0

Anyway, got the carbs cleaned up and mounted back on the rack. Tedious but not difficult. I'm hoping to see if the bike will start up mid-week, if I can find time between work and kids.

Scramps · « **Reply #30 on:** February 27, 2018, 09:50:27 AM »

I got lucky with my carbs, they were more or less clean and ready to go when I got them. They’re externally a little shabby looking, but everything was internally open and clean. I still replaced the carb bowl gaskets and o-rings, though, just as a precaution.

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DurangoCB · « **Reply #31 on:** February 27, 2018, 10:14:34 AM »

Quote from: Scramps on February 27, 2018, 09:50:27 AM

I got lucky with my carbs, they were more or less clean and ready to go when I got them. They’re externally a little shabby looking, but everything was internally open and clean. I still replaced the carb bowl gaskets and o-rings, though, just as a precaution.

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That's a nice bonus^. My CB500 was clean when I bought it, in all the ways that matter most (fingers crossed in regard to engine still). Two of the carbs being in pretty horrid condition was a surprise. I keep reminding myself that it really is about the learning and the journey. If it weren't, I would have just shelled out 10x as much money and I'd be rolling around happily on shiny new BMW R nineT and my wrenches would be tucked away in the toolbox.

DurangoCB · « **Reply #32 on:** February 27, 2018, 01:54:18 PM »

I managed to get a battery on this bike for the first time today and just had to get a video of the moment.

https://www.instagram.com/p/BftxzjGBPoy/

Clearly the fuel delivery is way off the mark, but we'll get that worked out. Anybody have a link to a good sequence/checklist I could follow for dialing in the carbs when they're this out of whack? I set all the air mix screws back to factory rec. Some had been way in the last time it was ridden, some were way out.

Anyway, all four barrels are firing, the carburetors are holding fuel and there's no oil pouring out onto the bench, so I'm celebrating.

Moto nut · « **Reply #33 on:** February 27, 2018, 05:21:12 PM »

That’s great!, that bike was pretty much idle for the last 25+ years, you’re doing all the right things, when I get to the point you’re at right now I’ll usually run rotella oil with an ounce of sea foam per quart of oil for a good internal cleaning for short periods of run time ( bringing up to operating temp ) while you fine tune the carbs, set timing, when happy with the way the bike runs and your ready for a test drive, drain oil and replace with a good quality motorcycle oil.....

DurangoCB · « **Reply #34 on:** February 27, 2018, 06:11:11 PM »

Sounds like a plan- thanks for the tip. I have a couple bottles of Seafoam on hand, so I'll drain a few ounces of oil and replace it with Seafoam.

Over dinner tonight I was expounding to my kids about the wonders of a combustion engine, how amazing they are and then how much more amazing when one that is 46 years old and sat for more than half of its life is willing to come back from hibernation and start growling again.

calj737 · « **Reply #35 on:** February 28, 2018, 03:54:01 AM »

Be careful putting SeaFoam in your oil. These are wet clutch bikes, and SeaFoam can produce adverse effects on your clutch plates. It’s great for fuel, not so great fro every wet clutch bike.

Moto nut · « **Reply #36 on:** February 28, 2018, 05:15:47 AM »

YEAH, like I said before you ride, replace the cleansing oil that has the sea foam....

seanbarney41 · « **Reply #37 on:** March 01, 2018, 07:10:26 PM »

from your video, what makes you think it was running on all 4?...sure didn't sound like it

DurangoCB · « **Reply #38 on:** March 01, 2018, 07:54:34 PM »

All four headers were hot.

seanbarney41 · « **Reply #39 on:** March 02, 2018, 03:52:17 AM »

Ok, could be wrong

DurangoCB · « **Reply #40 on:** March 02, 2018, 05:54:41 AM »

Quote from: seanbarney41 on March 02, 2018, 03:52:17 AM

Ok, could be wrong

You're right if what you were saying is it sounds like crap in the first 5 minutes after sitting for 23 years. LOL I wasn't expecting too much from her.

seanbarney41 · « **Reply #41 on:** March 02, 2018, 09:34:23 AM »

Well, if everything was right, except for say, a bad plug wire, or a plugged idle jet, it's gonna sound like crap whether it's 40 years old or brand new...I have fired up "just a few" of these.

DurangoCB · « **Reply #42 on:** March 02, 2018, 09:49:55 AM »

Wait- are you under the impression that I have this thing tuned and I think the way it sounds is peachy?

Haven't touched the valves, ignition timing, or cam chain. I just wanted to see if the bike would start and it did.

If there's a way that all four headers would be hot without all four cylinders firing, I'm all ears.

seanbarney41 · « **Reply #43 on:** March 02, 2018, 02:49:31 PM »

I did assume you had done that stuff...I have been fooled by pipes that get kinda hot, but its not really running. Pipes should be hot enough to vaporize a good squirt of water within a couple minutes. Cylinder may be firing intermittently or only when the throttle is opened enough for fuel to be drawn from the needle jet.

DurangoCB · « **Reply #44 on:** March 08, 2018, 01:36:47 PM »

Quote from: seanbarney41 on March 02, 2018, 02:49:31 PM

I did assume you had done that stuff...I have been fooled by pipes that get kinda hot, but its not really running. Pipes should be hot enough to vaporize a good squirt of water within a couple minutes. Cylinder may be firing intermittently or only when the throttle is opened enough for fuel to be drawn from the needle jet.

That makes sense. I've owned bikes since I was a kid, but I've never owned a vintage bike and I'm so damn excited that I'm sure I was more giddy than it deserved just because that bike made noise after almost 30 years. I've settled back down.

In fact, last night it all started getting real, or feeling that way. I have many questions and hope you fellas have answers.

DurangoCB · « **Reply #45 on:** March 08, 2018, 01:38:29 PM »

I started designing an under-seat battery tray last night. (I realize half of you will stop reading at this point. LOL) I plan to make it myself, but unfortunately I also started welding just last night. NOT PRETTY, so far.

Never underestimate the humble cereal box.

For those of you who have made or purchased battery trays, how deep is yours and what do you have in it?

DurangoCB · « **Reply #46 on:** March 08, 2018, 01:49:27 PM »

Disassembly is about 3/4 done and I felt a little like, "Oh Shinto, what have I done?" But we'll get there, little by little.

Ordered several new things.

Aftermarket MC and inline front brake switch. New SS braided brake line. New front caliper piston seal.
MAC 4-into-1 exhaust with reverse cone (scored a pro deal through a friend)
Dunlop K-70s (couldn't afford the Avons)
Exhaust gaskets (mine didn't have any?)
Oil Filter bolt (old one came loose easily but the head was chewed up and rusty enough to make me nervous)
New headlight mounting brackets. Not sure what HL I'll use, but LED would be nice if it didn't look TOO Sci Fi.
Pods and jets (my ticket into a cage fight between myself and my carburetors?)
Weld-on Kickstand since the original owner cut the mount off the frame to accommodate the 4-into-2 exhaust.

The next steps are to detab the frame, weld a kickstand back on, then either send the frame to powder or buy a gun and paint it myself. Then I have about 60 hours of polishing ahead of me.

DurangoCB · « **Reply #47 on:** March 08, 2018, 01:51:35 PM »

Speaking of polishing, I get the impression that once the uppers are rusty like this, you either have to cover them up with something, replace them or ride them rusty.

True? No chance at all of polishing them back up, even somewhat?

By the way, those headlight brackets that have a rubber plug that almost seems DESIGNED to trap water in them... dumbest design ever?

DurangoCB · « **Reply #48 on:** March 08, 2018, 01:56:20 PM »

Ah, electrical. All the mechanical stuff, suspension, bearings, engine (mostly), even paint and relacing my wheels... all of that I feel very confident with. What is giving me some anxiety is the wiring. It's all greek to me. Resistors, blah blah blah. I have a step learning curve ahead of me because I am yanking ALL of the stock wiring.

I want to relocate a couple things, but even if I didn't, the stock wiring is brittle and so hard to work with. I'm going to build a new loom from scratch so I can use a Li battery, relocate the ignition key switch to the L side of the battery box, etc.

Anyway, long leadup to a simple question. What is the trick to get these brittle old connectors off???

DurangoCB · « **Reply #49 on:** March 08, 2018, 02:01:44 PM »

And finally, just wanted to share one of the 2-3 bikes that is driving my vision. I know most of you here have already seen it, since Justin used to be an active member of SOHC/4.

Obviously, I'm not going to create a custom muffler like that and I do want turn signals (and a center stand... and my carbs will have drain tubes LOL), but otherwise, that's pretty much how I want my bike's stance to be. And I'm copying the color scheme, at the request of my wife, who I will hopefully be giving the bike to.

I also want some manner of front and rear fender. Something at least partially effective but minimalist. Probably chop the stock fenders.

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Author Topic: '71 CB500 Four Scrambler (Read 23749 times)