Author Topic: 1971 CB500 Shed find. Rust to ridable? (Read 4357 times)

matt167 · « **Reply #25 on:** June 12, 2021, 04:50:04 PM »

Is there any reason I should not cut off the original intake boots with a knife? That will allow me to slide the carbs out with ease it seems and they are going in the trash anyway.. I made and received the order from 4-1 and I made sure to get a full set of intake and carb boots

Mark1976 · « **Reply #26 on:** June 13, 2021, 06:52:54 AM »

It's your bike, and if you've got replacements on the way, that's one way. But now you've come across what everyone else experiences, just how awkward and difficult it can be to remove the carbs. I've learned that it if you remove The airbox its just less frustrating, takes a little longer, but the pushing and shoving and cajoling of the intake boots and carbs just isn't worth it. Besides ya get to clean the air & battery box see which of the breather and vent hose's may need replacing, which at this point in it's life, it could use. Just my 2 cents.

matt167 · « **Reply #27 on:** June 13, 2021, 08:53:13 AM »

I thought on a 500 you can't pull the airbox before the carbs? The box needs to come out for a cleaning anyway, but I have not tried due to reading that

matt167 · « **Reply #28 on:** June 13, 2021, 01:22:48 PM »

After looking, it became obvious what to do... The air box on my 500 at least is held in with 3 bolts. 2 from the top inside, and one from the bottom through the outside.. I used a swivel and a little patience to get the bottom bolt out, but the carbs did make removing it hard

Then I loosened all the clamps and was able to actually push the intake boots through into the mid air box giving lots of room.. All 4 intake boots are soft and serviceable, go figure.. Carbs pulled right off after that.

The one big problem I have is, carb slides are all seized. I knew at least one was as I had some throttle movement but it's evident it was just play in the linkages. All are stuck closed. However the slides look perfect. I could not get the drains open and, brown varnish runs right out of the vents. It's going to be messy taking them apart but at least I'm confident that they were in good condition when last used

Mark1976 · « **Reply #29 on:** June 13, 2021, 02:58:43 PM »

Once you have the carburetors off then disassembled, drop them one at a time in a can off parts cleaner (I use napa) leave each one in for 2 - 4 hours, that'll loosen them up. Rinse in hot water, blow dry and clean with compressed air. If they're still stuck, a little heat from a propane torch on the slide portion of the body will normally do the trick.

matt167 · « **Reply #30 on:** June 13, 2021, 06:06:05 PM »

I bought a can of Berrymans Chem Dip like 5 years ago because it was $5 on close out. I've never actually needed it

Mark1976 · « **Reply #31 on:** June 14, 2021, 06:24:28 AM »

Make sure you have a clean flat area that's not going to be disturbed. It'll take sometime to get them stripped down. You can do all at once or one at a time, unless you've got a lot of uninterrupted time you may want to tackle them one at a time. That can of cleaner isn't going to hold all of it a one sitting. I normally do one at a time, gives me the option of putting it down and walking away when I have to. The internal brass (mains and slow jet as well as needle and seat) will need to be carefully inspected. If it's varnished up very heavily they may not clean up, the brass I had in my cb550 from last year weren't salvageable so your not really going to know until you get to cleaning. One thing at a time.

matt167 · « **Reply #32 on:** June 14, 2021, 02:44:05 PM »

I have 4 full rebuild kits minus floats. I really don't want to use the aftermarket brass,

Mark1976 · « **Reply #33 on:** June 14, 2021, 03:52:18 PM »

Even if your brass cleans up (look closely at the brass they should have a keihin marking on them, the aftermarket has no markings other than size), your mains are going to need new o rings, otherwise it'll run rich. The emulsion tubes should clean right up. The slow jets are more problematic than the mains, they may or may not clean up, they're pretty small. There's going to be some felt o rings on the thru shaft that connects to the throttle slide, be careful with them, I don't believe they're available anymore. The rebuild kits are good for the float bowel o-rings, and the gaskets for the slide covers and maybe the needle and seat, that's about it. the original needle and seat may or may not clean up either, just look closely at them. keep the original mixture screws (again the aftermarket is junk). If you do them one at a time you don't have to worry about mixing the parts together. Post pic's if you can, it helps.

matt167 · « **Reply #34 on:** June 14, 2021, 05:25:29 PM »

I bought the kits from 4 Into 1... I'll be doing one at a time as that is the capacity of the dipper can that I have... I want to use as much original brass as I can. Is any of the aftermarket safe to use? I was under the assumption, that gaskets only were ok to use

Mark1976 · « **Reply #35 on:** June 14, 2021, 06:16:21 PM »

pull the bowels, post a pic...

matt167 · « **Reply #36 on:** June 15, 2021, 05:13:22 PM »

I forgot to snap a pic after I pulled the jets... The jets were about glued in place but I got them out. Might still be salvageable but I do have the aftermarkets.

Floats are stuck, and I cannot seem to even get any of the pins to budge. I used about 1 big can of carb spray so far

matt167 · « **Reply #37 on:** June 15, 2021, 05:30:24 PM »

I found JetsRus sells kits and OEM brass so I might buy some OEM stuff... If I replace the rotted exhaust with a 4-1 or 4-2, what kind of jetting should I do? I want factory exhaust, but not at $1,700 for reproduction. I may be able to put slip on's over the original pipes

rb550four · « **Reply #38 on:** June 15, 2021, 05:57:37 PM »

I've had great success removing the float pins with a hairdryer on HI, it takes a little time but worth it. Don't use a heat gun.

Mark1976 · « **Reply #39 on:** June 15, 2021, 06:22:36 PM »

Yeah, that's some ugly stuff, but if your careful, they'll come apart. You may need to locate a pin punch to get the float pins out. Be careful when tapping to remove them, the posts they slid thru can break. Once you have the float off you can remove the carbs from the racks and dump them in cleaner one at a time. Even after they've been in the carb cleaner the emulsion tubes can be a real prick to remove without damaging them. I've got extra's if ya need them. Get that done and see what ya need. Jetrus will do, but it's kinda hard to know what jetting your going to need, once you have an exhaust you'll have a better idea. I have a Carpy 4 into 1 that I bought last year that I'm not going to use, you could try that, It'll get ya close to stock jetting. There is a pic of it in my build thread, '76 550f barn find'.

matt167 · « **Reply #40 on:** June 16, 2021, 03:41:01 AM »

It's safe to clean the brass parts at the same time right? The O rings on the main jets as you can imagine are toast.

JetsRus has complete factory kits for $25 which include factory needle and seat. I might go that route and see what happens. I want to keep at least 2 pipes, to be as close to original as I can get

Mark1976 · « **Reply #41 on:** June 16, 2021, 04:22:44 AM »

matt167 · « **Reply #42 on:** June 16, 2021, 05:29:56 PM »

The pins are completly stuck. I tried the hair dryer and got 2 of the floats so that they will pivot on the pin, but will not free side to side... I used a small pin punch with as much force as I deemed ok as to not damage the towers and still nothing... A torch or boiling in straight water I've read from here that can work.

I did order a set of 550 carbs in better shape, as a plan B. I know they are not exact but cheap enough for a plan B

Mark1976 · « **Reply #43 on:** June 16, 2021, 05:49:14 PM »

That's fine, do what ya have to do. Patience pays, no sense trying to force things.

matt167 · « **Reply #44 on:** June 16, 2021, 06:08:23 PM »

Quote from: Mark1976 on June 16, 2021, 05:49:14 PM

That's fine, do what ya have to do. Patience pays, no sense trying to force things.

Is it safe to boil the carbs in water, float, slide and all as an effort to get things un stuck? The floats likely need replaced anyway.. The big problem is that I know this bike was stored with a tank full of gas and the carbs were not drained, the fuel bowl varnish stains being half way up the float bowl supports that, and the floats were submerged until they fully evaporated and what is left is basically glue.. I just knew to stop, check and research before I broke the towers.

I don't want to use the 550 carbs being I know they are slightly different, but can if I need to. I could re sell for what I paid easily if I can recover the 500 carbs

Mark1976 · « **Reply #45 on:** June 16, 2021, 06:45:03 PM »

Never boiled a carb, so I can't help you there. What model carbs did you buy?

matt167 · « **Reply #46 on:** June 16, 2021, 06:53:56 PM »

Quote from: Mark1976 on June 16, 2021, 06:45:03 PM

Never boiled a carb, so I can't help you there. What model carbs did you buy?

From a '76 CB550F.

Mark1976 · « **Reply #47 on:** June 16, 2021, 09:03:06 PM »

So, they should be 069A and have 98 mains and 38 slows vs 627B with 100 mains and 40 slows for a 71 cb500. They should just slide right on. I think thats what the 71 500 has. Your choice of exhaust will ultimately decide what jetting combination works best.

matt167 · « **Reply #48 on:** June 17, 2021, 03:26:21 AM »

Cool, so I'll just try them. Being that I have 500 carb kits, the only difference is the jets right? Because the factory jets on the 550 carbs will probably be ok.. Pulled from running but parted bike

Mark1976 · « **Reply #49 on:** June 17, 2021, 05:07:51 AM »

Verify what carbs you get, clean them up, go from there.

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Author Topic: 1971 CB500 Shed find. Rust to ridable? (Read 4357 times)