Topic: 71 cb500 project... let's see how this goes!

[dmccall1202]

Just picked up a 71 cb500 that was a barn find locally. Who knows how long it's been sitting. The person I bought it from said it was missing some stuff, obviously carburetors, and that he didn't think it'd roll and was all locked up. Was so excited that I didn't even check it out when I got there lol paid him 360 bucks, loaded it up, and hit the road. Eager to get into it and see what I want to do!

[Mark1976]

   Looks like a great starting point, what kind of mileage does it show.

[dmccall1202]

37,000 on the mileage. I assumed I’d probably be going through the motor.

[newday777]

Very cool.
The 500/550 is a great little power package that can out handle a 750 because of it being lighter weight to power ratio.
I have a friend with a 71 in a bit better condition and under 10,000 miles on it. I cleaned out the gas tank for him last fall as he had left gas in the tank from 2014  😢 but it turned out good after electrolysis cleaning and then Evaporust.

[wolf550]

congrats on the haul
it looked like a good deal when I saw it on FB
but for right now I can only look until I get the wifes 350 done and she learns to ride
it was pretty close to you down south TN.
keep an eye out near AL and GA as I see alot parts stuff near there

[dmccall1202]

 Very nice newday! I like the green a lot. Actually can’t seem to find this blue as an option they made. I’ll be cleaning this tank soon as well.

Wolf! That’s pretty cool that you saw this too. It ended up being about 10 mins from my house so super convenient. I eyeballed it for a bit looking for a 750 but I’m glad i picked up the 500!

[dmccall1202]

Got it home and cleaned up a bit this evening.

[dmccall1202]

And…

[dmccall1202]

Looks like the carbs are missing, battery, side covers, lights are broken too but I’m not sure what else from a try to get it running standpoint before tearing it apart for a restore so far as I’m not super familiar with these yet.

Good news is that after i cleaned it up and got wd40 on everything and aired up the tires the bike goes into neutral and rolls freely and also turns over with ease with the kick start.

Little overwhelming to know where to begin. I’ll get the tank cleaned first and figure out where to go from there.

[Mark1976]

   Put a rack on it, go thru the ignition, and see if it'll fire up.

[dmccall1202]

I’m assuming that if I’m not moding the engine I’d be best suited with a set of factory carbs? So I’ll look check the FS section and eBay for a set and see what I can find, clean the tank and see what happens.

Or since it looks like a set of carbs is a couple hundred bucks plus rebuilding them are there other options that I should consider? I’ve seen different carb setups talked about.


Need to order a key. The one that that I have is basically broke in have but i found the key website on here earlier today to order off the code. I tried to get one cut but mines pretty messed up and the one they made this evening won’t actually turn it.

[Mark1976]

   Post in the wanted section, someone here may have a respectable set, beats the heck outta the crap shoot that is the internet.

[dmccall1202]

Will do!

[calj737]

You’ll also need to replace the rubber insulators from the carbs to the intake manifolds. Plus, there’s rubber O rings beneath the manifolds that need replacing before you install carbs.

[dmccall1202]

I figured I’d need to replace the rubber boots to make sure I have a hood seal but good catch on the o-rings below the manifold Cal. I wouldn’t have thought of that until I pulled the motor and went through it.

I’ve noticed some new carb setups from places like Speed Moto that’s pretty much a new bolt on setup. Of course if i already had a factory set I’d just rebuild and move on but since I don’t and would need to source a set would something like this make sense or is the general recommendation from all to stay factory?

Seems like I’m probably gonna be around 350 to 400 bucks to get a factory set and go through them so if there’s only been 200 bucks more I was curious if it would be a better option to consider. I’ll also do some searching on here for people discussing these.

[Mark1976]

   Your gonna hate me for saying this but, get a set of original keihin's and the brass and the airbox as well, It'll just be easier. But that's up to you, it's your bike and your build.

[dmccall1202]

Not at all Mark. Factory was the original plan, air box may be the only thing i don’t do,  unless there is a better option for a similar price.

I’ve reached out to a couple of people from the fs section and also found a set on eBay that looks to be a fairly good deal condition wise to rebuild. Opinion on these?

https://www.ebay.com/itm/354729827163?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=bE1dvTo1RWC&sssrc=2349624&ssuid=lfRhqkKuT7m&var=&widget_ver=artemis&media=COPY

[calj737]

I’ve noticed some new carb setups from places like Speed Moto that’s pretty much a new bolt on setup. Of course if i already had a factory set I’d just rebuild and move on but since I don’t and would need to source a set would something like this make sense or is the general recommendation from all to stay factory?

Seems like I’m probably gonna be around 350 to 400 bucks to get a factory set and go through them so if there’s only been 200 bucks more I was curious if it would be a better option to consider. I’ll also do some searching on here for people discussing these.

There have been others that opted for a dual carb vs 4x setup. In the end, they all switched back to 4x. Tuning for a dual setup with foam pod filters just creates LOTS of headaches to get a smooth, well running bike. Can be done, but, you’re in for tortuous times if you choose that route.

“The most expensive bikes are free…” Or barn find relics where you only pay a couple of hundred bucks. It makes everything you need to buy to restore the bike expensive by comparison. You need to decide today, what is your goal with this bike? Fix it, make it run, enjoy it? Fix it, sell it? Keep it long term? All those options dictate your budget and elbow grease. Top condition, near factory “new” only sell for less than $5k. And it would need to be in near perfect condition to get that. Just bear that in mind as proceed.

[calj737]

Opinion on these?

https://www.ebay.com/itm/354729827163?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=bE1dvTo1RWC&sssrc=2349624&ssuid=lfRhqkKuT7m&var=&widget_ver=artemis&media=COPY

Those look very reasonable and complete.

[dmccall1202]

Thank you so much for the input Cal! This is what I was hoping to find out so it looks like factory is the way to go. I’ll pick these up or a set from someone who here if the people I reached out to still have them but it’s good to know these look solid if need be.

I absolutely knew this would be a full rebuild and costly at that. The only options I’ve seen in my area were old and in need of everything like this, hacked up bikes or once pretty much done and I wanted to do the rehab myself.

I have no intentions of getting rid of this once done and don’t really have a budget to stay under to turn it into what i want. Just want something to spend my time working on. But, if I have to buy something for it I’d rather get the best option for the money and not buy something to replace it later. Buy once, cry once i guess.

I plan to get it running then take it down to frame and redo it.

[dmccall1202]

Picked up a set of carbs, new key (mine is cracked where it was pinched over in the lock), new plugs, oil and filter, oem petcock and fuel line and everything to clean the tank. Should all be here by beginning of the week.

Got everything apart to start working on it too. The electrical seems to all be in place and the harness looks complete so I’m hopefully that I can get the tank cleaned up and everything together with the carbs and see if i can fire it up. That would be fantastic as I assumed I’d have to replace every single part on it before it’d even run. There is compression during kick over as well.

I’d like to get it running before i pull everything to know where I stand when it’s going back together lol

Quick question, I’m cleaning the tank with phosphoric acid. I have a new petcock as mentioned and plan to replace the gas cap with a new one.

Any issues cleaning the tank with the old gas cap and petcock in place so i don’t have to get plugs for all the openings? I won’t be reusing them so damage to them doesn’t matter. Just didn’t want anything spilling out while turning. I’ve read where people have left their petcock on with no issue or damage to the petcock but didn’t know about the gap cap.

Seems to be the easiest way since I’m replacing both.

Also, the carbs will need a rebuild as they were take apart for inspection prior to me purchasing.

Naturally I’ve read a million threads on the topic and know it’s recommended to keep everything Keihin. Anyone aware of anywhere that sells complete Keihin only kits? Seems like there is aftermarket and then there is piece everything Keihin together. Or is there a commonly recommended aftermarket in which I didn’t find?

[calj737]

https://jetsrus.com/a_jet_kit_street/honda_500_CB500K_1971-1973.htm

You can use old cap and peacock while cleaning tank, no worries. You can use a donor tank (plastic bottle IV type arrangement) to get it fired. Clear tube method for setting float heights and bench synching will get you very, very close to perfect provided the carbs are using stock brass and needle positions.

[dmccall1202]

Awesome! That makes things a lot more convenient!

I’m going to check them out when they arrive. They were in pretty good shape so maybe I’ll get lucky and they will have oem brass and i can just replace gasket and o rings.

I’ll Seward. For those methods and get them setup. I appreciate you!

[calj737]

Here’s a diagram on Clear Tube. Basically you make tube connection to the bowl drain screw and let the carbs fill with gas. The gas level is shown in the tube relative to its height in the bowl. Those Egyptians knew a thing a two about motorcycle maintenance back in the day… 

Bench synching is basically adjusting the slides equally using the shank of a 1/8” drill beneath the mouth. Adjust the slide until it just touches the shank. Do all 4 to the same position so that when installed, they pull nearly equal vacuum. A slight adjustment on the bike running may be necessary but this will get you very close.

[dmccall1202]

You are amazing! Thank you so much. The carbs came in today so I’ll get to work on them and this is going to be extremely helpful!