Author Topic: Marissa's 1972 CB500 (Read 95090 times)

RAFster122s · « **Reply #500 on:** September 16, 2019, 11:35:49 PM »

Sooty plugs can be from poor spark. If idle is not sooting up your other plugs then the cylinder you are having trouble with could have a spark issue. If the float heights are good then I would pull the plug cap and test it for peace of mind. It should ohm out at 5k. I think I would be tempted to change out the plugs to Denso from NGK with reports of plugs going bad quickly or out of the box. I forget HondaMan's recommendations for the Denso plug on the 550.

Glad you are making progress and were able to figure out one of your issues contributing factors.
Hang in there!
David

PS. A pipe that is bluing is a sign of a lean condition normally, not of too rich condition.

DaveBarbier · « **Reply #501 on:** September 17, 2019, 04:42:52 AM »

Bluing pipe could also be too rich if it’s reigniting in the header. That would make sense if the plug is black. But too rich or weak spark as David mentioned? Or fuel level raising because of grit or set too high.

Ignition timing is most likely not going to be the culprit.

Didn’t you replace all fuel lines with new?

You’re close! Everything you’re describing could be one issue.

RAFster122s · « **Reply #502 on:** September 17, 2019, 05:34:30 AM »

True, overly rich can be unburnt fuel in exhaust causing blueing. The bike will smell of unburnt fuel, hydrocarbons if it is that rich.

If sediment is causing floats to hang open it will have evidence of sediment in the float bowls. Clear tube will answer your question about float level. Only adjust if it is not in spec. Adjusting floats is not a common maintenance item.
Leaking floats can cause high levels as well. Fuel will be in float if it is leaking. If you have metal floats they can often be soldered to fix, plastic floats have to be replaced if leaking.
Bent float pins can cause float to not move freely and hang leading to high fuel level that is intermittently sticking. So,check to feel how freely the float is moving on the pins. Sometimes a bend in the metal tab where the pin rides can cause it to get tighter in one area as it moves.
These are some of the little things that have contributed to float level problems.
Float needle sides should be smooth, no visible rough areas also. I would not expect to see a issue here...especially since the float needles are recent.

Overly rich fuel reigniting in header is going to have wet black plugs if pulled soon after shutdown, dry sooty plugs is often weak spark.

Just a few more thoughts...

You are very close to whipping the issue.
David

HondaMan · « **Reply #503 on:** September 19, 2019, 08:17:55 PM »

Do you have a timing (strobe) light? If so, check the ignition timing at idle to see if the timing is on the "F" and "LF" marks. If not, the engine will run irregularly and cause vacuum disruptions in the carbs: this can make the float bowls bubble and bounce, causing them to intermittently overfill. In the Fours where timing is perfect and carbs are otherwise fine, a leaking intake valve can cause the symptom of intermittent [apparent] carb overflow for short periods of time, usually when riding in city traffic.

But here, seeing the Dyna S ignition (I think?) in the picture above, makes me suspect the idle timing is not the same between the 1-4 and 2-3 side - just because of our experience with these units here in the last 10 years or so.

Aside from that: the overflow tubes of gas can also come from one or more of the slide lifter elbows being loose: this makes the slide hang during decel on one carb, but not the next, causing increased vacuum in the (normal) carb throat, which then causes the bowl to slightly overfill. A few iterations of this and the overflow tube pukes some fuel, then the cycle repeats.

All of this comes from the other cylinders pushing or pulling on the otherwise 'normal' cylinders when these engines are not evenly timed, or breathing equally, by way of them all running one crankshaft.

RAFster122s · « **Reply #504 on:** September 19, 2019, 11:03:31 PM »

Dang Mark! Makes ya want to go to a single cylinder bike with that nightmare of perfect storm happening...

So, if the timing is fixed...then does most if not all these problems go away? Hope so...

Could a bent shaft at the points plate and advancer introduce a bit of wobble and therefore inconsistency in timing from 1-4 and 2-3?
David

Marissa · « **Reply #505 on:** September 22, 2019, 09:24:15 PM »

Started tearing down the fuel system again. Didn't open up the carbs yet but I found some questionable stuff.

Starting with the gas tank, I was working to get that empty and I poured the gas into a plastic jug to inspect it for sediment. Found 3 bigger pieces of black stuff, assuming it's old rust from the tank that never made its way out.

Then, I pulled the petcock apart. There is epoxy in it. This threw me off quite a bit so I pulled the borescope out. The liner does not appear to be failing anywhere. There's no lifting, there's no bubbling, etc. The entire tank is still coated and looks fine. I'm wondering if this is from when I had to bolt the petcock back in and I got epoxy on the threads. It was a mess to reinstall and it seems perhaps that this is the reason for the epoxy. I don't know what else to think of it. The circles are where there's a bit of this stuff hanging out.

Luckily, I have the filters on the lines still. There is actually nothing on those filters that I can see. I plan on making a really small hose adapter for the shop vac to pull this stuff out.
We will see what else I find.

Marissa · « **Reply #506 on:** September 26, 2019, 07:15:00 PM »

Okay, good news. The epoxy bits do appear to be entirely from installing the fuel valve. Found a big piece of it, also not pictured is a piece with thread imprints on it. Whew!

Going through all the carbs all over again and I found one of my main jets has this weird green powder residue on the inside. A result of contaminated fuel or something? I pondered brass corrosion but that would seem odd too.

Inspected and found that slide #1 was set slightly more open than the rest of the carbs. Perhaps this was doing something.

After taking the mains out and turning the carbs over on the bench, my emulsion tubes started coming loose. That's a problem, isn't it?

Thinking about trying 98 mains with the 40 slows and stock needle height when this is all buttoned up.

Scott S · « **Reply #507 on:** September 27, 2019, 02:22:12 AM »

The green residue is probably from ethanol in the fuel.

Did you vacuum sync the carbs? If so, it's not unusual for the slides to be slightly different.

The emulsion tubes are held in place by the main jet and the main jet spring clips/holders. The fact that they fell out easily just means you have clean carbs and jets.

CBJoe · « **Reply #508 on:** September 27, 2019, 03:05:42 AM »

Is it the flash in the pic or is the #1 slide super corroded/pitted?

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DaveBarbier · « **Reply #509 on:** September 27, 2019, 05:14:22 AM »

That’s slide is strange. It should be nice and smooth like the others.

I also woulndt be concerned with the green on the inside of the main jet unless it’s restricting the hole. Looks to be just a film.

Cb750 Racer · « **Reply #510 on:** September 27, 2019, 05:54:36 AM »

Quote from: Marissa on September 26, 2019, 07:15:00 PM

Okay, good news. The epoxy bits do appear to be entirely from installing the fuel valve. Found a big piece of it, also not pictured is a piece with thread imprints on it. Whew!

Going through all the carbs all over again and I found one of my main jets has this weird green powder residue on the inside. A result of contaminated fuel or something? I pondered brass corrosion but that would seem odd too.

Inspected and found that slide #1 was set slightly more open than the rest of the carbs. Perhaps this was doing something.

After taking the mains out and turning the carbs over on the bench, my emulsion tubes started coming loose. That's a problem, isn't it?

Thinking about trying 98 mains with the 40 slows and stock needle height when this is all buttoned up.

If you zoom in on the first pic you can see that slide #1 is extremely pitted. That's not the flash, definitely replace that even if that's not your problem with the throttle hanging.That's gonna be a problem in the future with that slide. Replace any others as bad and check if the corresponding area where the slide sits is worn out on the carb body because that pitting has had to cause some damage.

SF · « **Reply #511 on:** September 27, 2019, 10:20:46 AM »

It’s not that nice hard anodized colour either somethings reacted with the anodizing.

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Marissa · « **Reply #512 on:** September 29, 2019, 05:08:45 PM »

Thanks for the info guys. I'll be ordering other slides soon. All 4 were actually like that, and the only reason there is a clean one now is because I swapped that slide out since the screws for the needles were stripped.

While we are admiring how messed up these carb internals are, any chance anyone could tell me if this wobble for the main jet is normal? I have this fear that these are so corroded that gas is actually slipping past them.

Scott S · « **Reply #513 on:** September 30, 2019, 03:54:05 AM »

The O-ring is supposed to seal it there. You may have the wrong size O-ring on the main jet.

Marissa · « **Reply #514 on:** September 30, 2019, 08:16:29 AM »

Quote from: Scott S on September 30, 2019, 03:54:05 AM

The O-ring is supposed to seal it there. You may have the wrong size O-ring on the main jet.

Is it possible to have the wrong size o ring seal come already installed on the Keihin brand main jets? I wouldn’t think they would do that.

rosewood · « **Reply #515 on:** September 30, 2019, 02:21:35 PM »

Marissa can you remove the main jet and post a close up picture of the inner surface where the o-ring is intended to be seated?

This has been raised before and most people seem to think if the sealing surface inside that post still looks clean then it should be fine regardless of the corrosion/oxidation that is visible.

Is that a new mainjet and o-ring? if it is older the O-ring may have worn/flattened and need replacing...

I feel your pain....have been chasing similar issues myself..

Marissa · « **Reply #516 on:** October 01, 2019, 08:59:05 AM »

Quote from: rosewood on September 30, 2019, 02:21:35 PM

Marissa can you remove the main jet and post a close up picture of the inner surface where the o-ring is intended to be seated?

This has been raised before and most people seem to think if the sealing surface inside that post still looks clean then it should be fine regardless of the corrosion/oxidation that is visible.

Is that a new mainjet and o-ring? if it is older the O-ring may have worn/flattened and need replacing...

I feel your pain....have been chasing similar issues myself..

Sorry to hear you are facing similar issues. Let me know if you figure out yours!

Here's a picture of the insides. They look maybe okay to me? The jets are all new btw. Either way, for the price of buying slides individually on eBay vs. ordering a whole new carb rack, I opted to get a new set of carbs instead.

I'll tear down the "new" carbs, ultrasonic them, swap all my good pieces over, and slap them on and see where that gets me. Either way, the season is pretty much going to be over by the time I complete this, which sucks. But I'm hoping this is a step in the right direction and may eliminate guessing games.

Just got a truing stand in the mail, and a motorcycle jack should be here today as well. I will be attempting to true my wheels in the next few weeks.

rosewood · « **Reply #517 on:** October 01, 2019, 04:23:41 PM »

I'm no expert but it looks like the corrosion has gone up to and past the sealing surface of the o-ring..maybe ream/hone/clean with something and then try a thicker o-ring?

I think you are on the right track with replacing them for a better set though.

I pieced mine together from two sets which were both corroded, maybe not as bad as yours..I then came across a third set which was cleaner so have opted to use them...

I've had a float valve issues and rich running so far...but I need to get a new set of float valves before I go any further.

Have you thoroughly gone through your ignition system including advancer? check timing on both sets of points with a timing light at idle and advance? make sure your advance is not kicking in too early with weakened springs...

Quote from: Marissa on October 01, 2019, 08:59:05 AM

Quote from: rosewood on September 30, 2019, 02:21:35 PM
Marissa can you remove the main jet and post a close up picture of the inner surface where the o-ring is intended to be seated?

This has been raised before and most people seem to think if the sealing surface inside that post still looks clean then it should be fine regardless of the corrosion/oxidation that is visible.

Is that a new mainjet and o-ring? if it is older the O-ring may have worn/flattened and need replacing...

I feel your pain....have been chasing similar issues myself..

Sorry to hear you are facing similar issues. Let me know if you figure out yours!

Here's a picture of the insides. They look maybe okay to me? The jets are all new btw. Either way, for the price of buying slides individually on eBay vs. ordering a whole new carb rack, I opted to get a new set of carbs instead.

I'll tear down the "new" carbs, ultrasonic them, swap all my good pieces over, and slap them on and see where that gets me. Either way, the season is pretty much going to be over by the time I complete this, which sucks. But I'm hoping this is a step in the right direction and may eliminate guessing games.

754 · « **Reply #518 on:** October 01, 2019, 10:32:42 PM »

I would wet the oring before pushing jet in, and see if they wiggle... or turn easily....I will go watch your video.
if they are loose they may leak past them.

Another thing I am seeing.. (might just be my eyes)
Your slides seem to have a little burr or bulge at the middle of the cutout edge. this can happen if you use a screwdriver to unstick a seized set of carbs or maybe very rough trying to use a rod to synchronize on the bench.
Anyway if there is a deformation, it may alter the slide cutaway at idle, and if its a raised burr, may be scratching away at the hole in the carb, that the slide moves up and down in. If it wore a groove, it would not be good.

Marissa · « **Reply #519 on:** October 19, 2019, 01:52:49 PM »

Update!

Dave Barbier and my boyfriend came over a few weeks ago, the three of us worked together one Saturday to completely rebuild the "new" carbs I got and see what that would do. A few hours later, we go around to getting the bike ready to fire up and low behold, my Shorai battery was deader than dead. Funnily enough, I found out a week later I purchased it exactly a year ago. I have been charging it with a trickle charger, guess it didn't like that. Also oozing out some goo from the charging port. So after a wasted night, I purchased a new Shorai and a Shorai charger.

Today I finally had time to put the new battery in and start it up. Took a little bit but once it took it was sort of promising. I played around with ignition timing a bit and I got it pretty good; only thing is it's overflowing into the drain tubes.

So it instantly dies with throttle. Super rich, of course. Next time I have time these carbs will be coming off, floats will be tested on the bench with the clear tube method, and hopefully this is the only thing stopping it. On the bright side, at least all of the cylinders are showing very similar results.

#4, reflection from being wet with gas

#3

#2

#1

A few of the other goodies I got to make the bike nicer over the winter.

RAFster122s · « **Reply #520 on:** October 19, 2019, 07:37:04 PM »

Congrats on the promising progress. I hope you are able to get it dialed in to get it on the street for a while before you have to put it away for winter.

Marissa · « **Reply #521 on:** November 03, 2019, 06:38:10 AM »

No progress yet, busy with school and work.

I’ve been thinking about the bike in my free time and I think it might be a good move to change out the ignition system for a more common and known to be reliable system just to rule out my lack of confidence in this ignition and the timing that it tells me it wants.

I like Charlie’s system, but it seems like most use Dyna. Is it only worthwhile to get the Dyna 2000 system or is the more simplistic and cost effective Dyna S perfectly acceptable and reliable?

MauiK3 · « **Reply #522 on:** November 03, 2019, 08:40:19 AM »

The stock points system is very reliable. If you wanted to go one step further you could install Hondaman's transistorized unit so the points become just the trigger and not the load bearing switch. The points system along with stock coils put less electrical load on the alternator too. It's one of those "if it ain't broke" things.

Mark1976 · « **Reply #523 on:** November 03, 2019, 02:04:04 PM »

+1
Hondaman,
Best ignition investment I ever made.

RAFster122s · « **Reply #524 on:** November 03, 2019, 07:18:39 PM »

Quote from: MauiK3 on November 03, 2019, 08:40:19 AM

The stock points system is very reliable. If you wanted to go one step further you could install Hondaman's transistorized unit so the points become just the trigger and not the load bearing switch. The points system along with stock coils put less electrical load on the alternator too. It's one of those "if it ain't broke" things.

One should not that when you put a new set of TEC points in with HondaMan's electronic ignition box it will be the Last set of points you buy as long as you have HondaMan's ignition installed. Can't beat that with a stick! Seriously, better starting feels like the ignition timing (After you take a loop or so off the advancer springs... measuring the rpm that the advance reaches full advance until it is at the recommended values for each of the SOHC4 bikes.) And, it provides better cold starts, improved idling in transitions to full advance and beyond. The bike gives the impression that it is smoother and stronger going up through the gears, it feels different from a stock points, feeling better of course...
I am shocked how cheap it is...given the benefits it provides it is worth every penny! Today it is a great value when considering the cost of simple things for a bike , much less a quality electronic box like this and it's function.

My $0.05 worth.
David

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Author Topic: Marissa's 1972 CB500 (Read 95090 times)