My new plugs after a glorious 120 mile ride on country roads in NC.  The soot on the left plug is easily cleaned. You can see the glisten of oil on the right, but it’s not as bad as in the past. Engine oil level has stabilized at the midpoint of the high/low lines on the dipstick. 

I’ll take a look at the left carb float bowl - the carb is not leaking gas but maybe I can adjust the tang (again) so the float needle closes sooner.

As for the right, there’s a little oil at the end of the breather hose near the plastic air intake attached to the airbox. I’m going to try cleaning the breather valve before I resort to pulling the thing out.

It was a beautiful day and the bike ran great. Temps in the mid-70s, clear skies, no traffic, and in the company of a good friend who is also an airhead owner.  Doesn’t get much better than that. 

Scott, not for nothing but the right plug looks normal.   Wait a bit on pulling the breather until you have ridden with the stable oil. There will always be a bit of oil in the breather tube, LOL the  million dollar question is when is a little too much?

As for the sooty plug, That is not normal.  But I don't think it is oil related, more rich mixture problem.  

As Richard mentioned perhaps new wires and caps are needed?  You may not be getting proper spark.

The other issue sadly could be the carbs are in need of rebuilding and a good internal cleaning.  I agree with Richard this is an old bike and if the carb seals/o rings are original, they could be shot.

There is also the carb diaphragms to consider, a worn diaphragm may not pull off properly and cause mixture issues.  Again if original parts, they most likely should be replaced.   They are not a high cost item nor difficult to replace.

As for valve seat contain, you will be able to look at the valves when you remove the heads to replace the leaking push rod seals. I very much doubt with the low miles you will need valves or seats.   

As I mentioned, you can have a leak down check done, that will determine if there is valve leakage.  Again, I doubt there is an issue with the valves.

Good luck, St.

Thanks. 

I'll pull the carbs off and go through them.  It's been a year since I rebuilt them (new diaphragm, gaskets, floats, float needle).  I have brand new spark plug wires and caps (5K ohm for the new ignition) - this was my first ride with them.  The coils are new, too (3 ohm, as spec'd for the ignition).

Scott, LOL, one thing if you go back over the carbs you will be checking your work.  Not saying you rebuilt them wrong but not everyone is perfect.  

Just thought of something also to look at. Are the chokes pulling off as they are supposed to?  Could one choke cable be hung up?  Are they adjusted properly so they are off when they are supposed to be.   If you had them apart in the past, recheck your assembly.

At least on the left sooty side.  St.

Choke is okay. I obsess about making sure the choke lever on the carb is bottomed out.

When I first rebuilt the carbs after buying the bike, I saw that the left one was incorrectly assembled. The diaphragm was not attached to the slide. The bike ran much better after fixing that…🙄

But yeah it’s time to take another look. 

Hello Scott, if you get back into your carbs, and you didn’t last time, I would replace the slide needles and needle jets. It looks like (on that Bing chart I sent you) that you should have 268 needle jets, and your needles should be at the second clip position. The slide needles and needle jets are the big players in the mixture when you’re running down the road. And, the needles and needle jets wear over time. As they wear, the mixture gets more rich. 

Posted by: @4949

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Hello Scott, if you get back into your carbs, and you didn’t last time, I would replace the slide needles and needle jets. It looks like (on that Bing chart I sent you) that you should have 268 needle jets, and your needles should be at the second clip position.

David has given you an excellent suggestion. 99% of your riding is done at mid-range on "the needle". The intake pulse basically takes the needle (which protrudes through the venturi) and hammers it back and forth, which distorts both the needle and the needle jet slowly over time. So, the needle and needle jets are replaced based on mileage. 

You cannot see or measure this wear. These parts are made with the same precision as a Rolex watch and it really doesn't take much to upset the delicate balance. 

Scott -

Buddy, we want to help you here, but you are still not telling us very much. If you want to take a casual approach to the solution and guess, then you will be here a VERY long time and you will be replacing a lot of items needlessly. It's your bike, your money, your problem, your time and you, of course, are welcome to guess all day long. 

I prefer to take a more scientific approach, which requires a set base line (a known starting point) and then a systematic approach to the solution. 

Here's the issue I have.... You have changed the plugs, but nowhere in your description nor in your photo can we tell what plug number you used. At least to me, the heat range of the plug is a critical piece of information if you're going to read a plug. Secondly, you have not told us your procedure for taking this "reading".

To me, these are both basic (foundational) pieces of information. So, I'm going to bow out of this thread. All the best.

Scott, this may be a long shot and simple to check.  On the top of the carb is a disc pressed in.  After many miles and years, one of my carb tops developed a small leak there that messed up the vacuum actuation of the slide in the carb.

So check for a vacuum leak at the top of the carb.  LOL, check for leaks anyway though usually vacuum leaks result in lean conditions and this is not what is happening on the left side.

In regard to the needles and clip settings, double check that you have both needles on the same notch Dave gives the position.  

Seriously I think this will be a simple fix, something is out of place or adjustment on that particular carb.  The other side looks fine. St.

Scott, I see a partial number for the plugs, 6ES, Is this NGK BP6ES?  This would I assume be a cooler version than Richard's suggested NGK BP7ES.   

The cooler spark plug would be an issue in my mind if BOTH plugs were looking the same.  St.

Let me summarize so far as I see things.  This is NOT a crankcase breather issue, it is not a bad piston ring issue, nothing to do with oil.   It is a rich mixture issue due to a carb problem or spark plug wire issue, though I doubt that as the bike is not misfiring. 

It is not an improper range of spark plug issue, one plug looks fine the other is off.  Could it be a spark plug issue, swap the plugs left to right and repeat the ride.  Again because the bike is not misfiring, I do not believe it is ignition.

So, and this is not a guess, based on what data we have there is an issue with the carb on the left side.  I have covered some places to look at.  

I don't want to step on David's toes but I kind of doubt it is needle and seat wear.   I write this because of the mileage on the carbs.  I myself haven't seen needles and seats wear out that fast or at such low mileage.  

David, if you have seen this, happen on your bike or on another bike, I will accept it and add it to my list of things to remember.  Also, again one plug looks good, so one side of the bike is running properly.  

I cannot imagine one needle and seat in one carb wearing at a greater rate than the brother needle and seat.  Then again, there is such a thing as bad parts from time to time.   

So Scott is going to recheck his rebuild and adjustments.  

LOL, I remember one time I rebuilt a set of carbs and a part dropped off the bench.  The carbs worked sort of, the bike ran fairly well, but not quite right.  It wasn't until I matched the inners of the good carb to the bad one, I discovered the missing part.  Lesson learned.

Don't tell Richard that story he thinks I am incompetent enough.  St.

I agree, the slide needles and needle jets should last many miles, and it is unlikely that one side would wear differently. Myself, if it were a “new to me” bike, I would put in fresh needles and needle jets - if you did not when you rebuilt the carbs a year ago.  You just never know what a previous owner has done, or not done, or swapped parts from something else, etc.  You said this has been happening since you bought the bike. I would confirm, by carb number on the Bing chart, that all the jetting, clip position, etc. is all correct.  Then you can feel confident where you are starting from.

Then, of course, the diaphragm must be good.  No vacuum leaks.  If it’s still running rich, then what could cause this?  Float level too high, or float sticking (I’ve had that).  Or, something amiss in the choke circuit that’s allowing fuel to be pulled in even with the lever against the stop.  I once bought a package of plastic vacuum caps at the auto parts store, and used a little tiny one to cap off the suction tube for the choke circuit in the bowl, cuz I suspected it was drawing fuel.  It wasn’t, but it was a good experiment.

David, you gave some other good advice.   I had not thought about.   LOL, I agree whole heartedly with you in regard to what I call "Previous Owner's Disease".

My friend's shop had a bike in last summer with two different carbs.  The mechanic who set them up used the specs for one of them and set both to the same.    As you mention upon discovery, each carb was set to it's own specs and the bike runs so much better.

I like the idea of the Vacuum cap to test the idle circuit.  

I am really hoping this is a simple fix, something like just a misplaced part, a bad o-ring or float level issue.  LOL, much as I want answers now, I realize Scott has other things to do besides work on his bike.  Patience was never one of my long suits. St.

Hey guys - thanks for all the suggestions!  I had to attend to the rest of my life for a bit... 😀 

I pulled the carbs off to check the jet needle settings, and the right side (lean) was a click "lower" than the left (rich).  Stupid.  I would have sworn that I had set them the same, but there you go.  That part was an easy fix.  

Now they are set the same - 2nd click from maximally rich, which is where I started originally - and now both sides are running rich. That's good news! I'll go back and drop them another notch - 2nd click from maximally lean (as David suggested) - and see what I get.  I'll also check for clogged channels, replace gaskets, etc.

I picked up a leak down tester - a Maddox unit from HF.  It looks better than the Pittsburgh brand.  I'll run a test later this week.

Again, thanks for all your help - much appreciated!

-Scott

Posted by: @18392

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I pulled the carbs off to check the jet needle settings, and the right side (lean) was a click "lower" than the left (rich).  Stupid.  I would have sworn that I had set them the same, but there you go.  That part was an easy fix. 

Poop happens. One can set the needles distance perfectly, then the needles can get knocked down 1 or 2 notches if extreme care isn't used replacing the slide back into the carb. This is why I ask people to check. 

Posted by: @18392

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I picked up a leak down tester - a Maddox unit from HF.  It looks better than the Pittsburgh brand.  I'll run a test later this week

In my humble opinion, a Leak Down Tester will tell you nothing useful. Honestly and truly, I'd return it and buy a good compression tester and/or an ignition timing strobe light.

• But congratulations on "turning the corner". You seem to have matters well in hand now.   👍