Gray smoke spit from carbs

[AgentX]

In brief, what does gray smoke spitting from the carb indicate?  (Besides my mechanical ineptitude.)  Happening sometimes on start, sometimes while deaccellerating to a stop and then stalling.

Causes/fixes?  Thanks.

[ace.cafe]

Lean mixture on the pilot circuit.

[AgentX]

Lean mixture on the pilot circuit.

Interesting, thanks!  I will go to a 35 pilot and see how that works.

I have another probably related situation:  When I engage the enrichener/choke, the bike will not start, or it dies if already running.  But it starts pretty nicely without the choke when cold; you do have to give a little throttle just after you kick it over to get it to keep going, though.

I thought this meant I was too rich on the pilot--that the enrichener was giving an over-rich mix which would not start, and that the regular mix was decent, if not perfect, for starting.  Obviously, I was wrong.  Any thoughts on what this indicates, or how to fix it?

[ace.cafe]

If you are needing to go to a 35 pilot, and don't need the enrichener, then maybe it needs to be slightly leaner instead.
I may have jumped the gun on this before having all the facts.
I'd keep the 30 pilot, and use the air bleed screw to try to get it dialed in by screwing the bleed screw out until it behaves better.
Then re-adjust the idle speed with the big screw when the bike is heated up, and that should help. If you adjust these things when it's hot, then it doesn't die at stop lights. Then you use the enrichener for starting.

[AgentX]

I am still baffled by my bike.

When I run through the procedure for setting proper idle with the bike nice and warm, the air screw is always near-fully out (leanest).

Yet I have the gray smoke spitting problem reasonably frequently, and the bike still won't start with the choke on.  I put in jets just over stock size owing to my use of a K&N filter and open header with a short megaphone muffler, minimal baffling.  I also installed a new spark plug at that time.  It was black and looked a bit oily when I pulled it out today after 80 miles or so.

I figured it HAD to be a vacuum leak causing this, but I tried spraying WD-40 and couldn't find anywhere that made the engine race.  Could it be something else?  Ignition timing off, or bad coil??

[ace.cafe]

It's possible that you have some worn things in your engine, which might cause it.
If you had leaky valve seats, that can cause spitting back thru the intake. And leaky valve guides can cause oily spark plug.

And an exhaust leak at the head joint might cause a lean mixture condition and spitting, so check your header pipe fit into the head for any leaks or visible carbon showing around the header pipe joint to the head.

[AgentX]

It's possible that you have some worn things in your engine, which might cause it.
If you had leaky valve seats, that can cause spitting back thru the intake. And leaky valve guides can cause oily spark plug.

And an exhaust leak at the head joint might cause a lean mixture condition and spitting, so check your header pipe fit into the head for any leaks or visible carbon showing around the header pipe joint to the head.

thanks--will check as best I can.  The cylinder head rebuild by the shadetree jackass I paid to do the initial work sure isn't precluding any of that.

How would you check for a leaky valve seat or guides?

I've been regularly looking for soot at the exhaust header join, though, and not found any.

[barenekd]

Your timing could be a bit retarded.
The carb sounds quite rich enough.
Bare

[ace.cafe]

thanks--will check as best I can.  The cylinder head rebuild by the shadetree jackass I paid to do the initial work sure isn't precluding any of that.

How would you check for a leaky valve seat or guides?

I've been regularly looking for soot at the exhaust header join, though, and not found any.

Normally to check for leaky valve seats, you check your compression with a compression gauge first. Then if compression is low, it's either valves or rings. Check for rings by adding a few ccs of oil into the cylinder thru the spark plug hole, and check compression again. If compression raises substantially more, it's rings. If it doesn't, it's valves.
If you have no compression gauge, you can remove the head, and put it on the bench with the combustion chamber facing up, and pour some light oil or ATF into the combustion chamber enough to fully cover the valves. If the oil or ATF leaks past the valves into the ports, your valve seats aren't sealing, and you need a valve job.

Regarding guide leaks, many Bullets don't have valve stem seals, but some of the later models do. If your guides are worn, or stem seals have gone bad, oil drips down the guides and gets into the cylinder, and leaves oily deposits on your spark plug. Oil in the combustion chamber is generally not good, and can be a cause of detonation in some cases.

Most of the time these spitting and dying symptoms are from poor tuning. But then can be from engine problems. Work on trying to get good tuning first, and if you can't get it tuned right, then look at engine issues that I mentioned.

[Bullet Whisperer]

It would be worth checking that the pushrod adjusters are set correctly, as they might be too tight. Make sure you can spin the pushrods easily at TDC on the compression stroke.
 B.W.

[Arizoni]

If my sparkplug is black after a 80 mile ride I assume either the fuel/air ratio is too rich or my sparkplug is too cold of a heat range.

Of course, once I thought I was wrong but I was mistaken. 

[Kevin Mahoney]

This is shade tree mechanics at it's best. It was shown to me years ago by an old hand at the factory. I use it but never admit to it. If the compression of your bike is good enough, a reasonably sized person (not me) should be able to gently stand in the kick starter at the top of the compression stroke and the kick starter should hold you. Crude but effective

[AgentX]

Kevin, that's what I've been told too, but I've never seen a 350 that could support the weight of a grown man for more than a few seconds...might well be the fact that everyone's bike here is clapped out to some degree.    Mine won't hold me past 2-3 seconds, but it's only got around 275 miles on new piston/rings/cylinder and it feels very good by local standards.

Ace, no idea if I can find a proper gauge locally.  I know they exist but dunno if they're any better than the Harbor Freight cheapies found in the US.

I began to suspect this was an ignition/timing issue, so I went and replaced the contact breaker plate, with new points and condenser.  The old auto-advance unit seemed much smoother than the new one I had, with nothing disconcerting going on, so I left it in place.

I tried ping timing per Snidal and settled on about 2/3 of the way advanced.  I never got a clear pinging like a spraypaint can being shaken (heard that on my UCE 350 once); at best when I was on or past 3/4 throttle on the hill I heard a vague rattle underneath the engine and valve clatter.  Bike also became really hard or impossible to start around that setting, so I backed off a bit and seem to have found the sweet spot.

But it didn't solve the spitting problem and idle remains lumpy despite my continued best efforts to tune it smooth.

Question, though, since the guy who put the bike together did many suspect things...if I'd been unable to make it ping when fully advanced at the contact breaker plate, what then? Can you just break/re-set the taper and start again?  That was my only guess.

[ace.cafe]

You can re-set the taper and move the points plate to start over again, but it seems to me that you are probably in the neighborhood.

In some cases, being too rich can cause a spitback too.

Part of this problem is because there is so much overlap on these stock cams, and it is ridiculous for such a mild output engine. There is no reason at all for these cams to be opening up the intake at 50 degrees before TDC, and I have seen that on plenty of these stock cams. Even the factory spec of 40 degrees before TDC is too much for this low-revving low output engine.

Having the intake open while there is exhaust pressure still in the cylinder is a recipe for reversion. If there is any unburned fuel in that exhaust, and a hot spot sets it off when the intake valve is open, it spits back thru the carb.
It can have this unburned fuel in the cylinder if there is a misfire, or if it's too lean, or sometimes if it's too rich.

[AgentX]

Thanks for the explanation, Ace.  Makes things clearer yet more complicated, I guess...

I will try going down to the stock jetting and see how the plug reads; will be careful not to get overly lean, but it doesn't seem like I'd be in the danger zone given the current setup is only 30/105.  When I got it, it had a really big pilot jet (looked hand-drilled and I had to ez-out it anyhow, destroying any markings) and the stock 90 main jet, and didn't give me these problems.  I will keep my eye out locally for a 28 pilot and 95 or 100 main which seem rare as hen's teeth.

Maybe my muffler isn't as free-flowing as I thought.

Given your explanation and the fact that this started when I went richer, the answer now seems easy.

Still don't know what's up with my excessively lumpy idle, but I think maybe it comes down to a fairly sketchy alternator...I think either the rotor or the crank stub itself is just off true.  It wobbles a bit and I think that definitely affects its output; getting it to run without contacting the stator is a real chore. 

I am going to try using a Boyer powerbox to see if the capacitor smooths things out; found one lightly used for a great price at Hitchcock.

[AgentX]

Hm.  I went to a 25 pilot and a 95 main (stock is 25/90) and things have gotten a little better.  Yet, it's still rich. 

Spitting back has been greatly lessened but it happened, weakly, once or twice today.  Starting can now be done with the enrichener engaged, but requires some throttle to be added.  Same without the enrichener, but less throttle obviously required.

Did a plug chop at a very low speed then took the plug right out; came up with what I thought was oil on the plug and I got worried.  After a short ride around the 'hood at low speed, I waited a few minutes to pull the plug; it was sooty and insulator was very dark brown.  No sign of oil. So I am assuming that the blackish liquid I first saw was just carbon that had come straight out of the still-very-hot-engine.  Carbon residue on guns is liquidy at first, so I'll make the bold assumption it's no different from an engine.

Still, don't know why I'm so rich, but a turn or two more out on the air screw might cure that.  Or should I be looking to another cause? 

Float height is good.  I pulled the enrichening plunger from the top and cleaned it, too.  Is there anything else in the enrichening circuit which could cause it to feed extra fuel to the carb even when the choke lever is disengaged?

Just seems odd that I'm on stock pilot jetting and still rich with a K&N filter and an open header/megaphone exhaust. 

Idle is still a little lumpy but I've been able to get it smoother.  It's been a challenge adjusting the pilot mix because the beat was so uneven it was hard to tell when the bike was reacting to the mixture change instead of just another seemingly random fast or slow point.

Thanks for listening...

[AgentX]

doublepostungood

[ace.cafe]

What is your elevation above sea level, and what are the approximate outdoor temperatures you are seeing?

[AgentX]

1800 feet AMSL, and right now it's 70s-80s (F) daytime, will drop to 60-70 in the winter and up to 115 daytime in the summer...

[ace.cafe]

1800 feet AMSL, and right now it's 70s-80s (F) daytime, will drop to 60-70 in the winter and up to 115 daytime in the summer...

Well, that's high enough in elevation to make a difference in carburetion.
Try a little leaner in the pilot.

[AgentX]

Roger, copy all.  Tango, out.

[Arizoni]

Before you change the jetting, you might try running the bike without the K&N filter in place.

While I'm not the type to believe in running long distances without a air filter in place, a 25-30 mile ride  shouldn't do any real harm and doing this might confirm or eliminate the filter as a part of the problem.

[jdrouin]

Also check that the little rubber grommet at the base of the enrichener shaft is attached to the brass (or whatever) base. If not, it prevents the enrichener from closeing completely and you'll run extremely rich. I was fouling plugs last year (oily or gasoline-y) before someone finally suggested the grommet and it turned out to be the culprit. I re-attached mine with silicone sealer and it hasn't given me a problem since.

Jeff

[AgentX]

Also check that the little rubber grommet at the base of the enrichener shaft is attached to the brass (or whatever) base. If not, it prevents the enrichener from closeing completely and you'll run extremely rich. I was fouling plugs last year (oily or gasoline-y) before someone finally suggested the grommet and it turned out to be the culprit. I re-attached mine with silicone sealer and it hasn't given me a problem since.

Jeff

Jeff, that's interesting--I took the plunger out from the top to clean it, since I wasn't at a point where I was willing to pull the carb off for the fourth time that day.  Next time I have it off I'll take a better look inside.  Could be part or all of the problem.

Arizoni, I have run it without the filter before...not much of a difference to running it with the filter on.  But it's something I'll try again if all else fails.


Ace, I threw another turn out on the air screw on the way in today, and it ran better.  Maybe it's the altitude or maybe it's something wrong inside the carb as Jeff suggested.  Luckily the carb is pretty simple so it shouldn't be rocket science to determine it's working properly.

Thanks again, guys.

[ace.cafe]

If you need to turn the air bleed screw out more than 3 turns, you need to move to the next leaner pilot jet, and re-tune with that.
And on the other end of the scale, if you can turn the air bleed screw all the way in, and the bike still runs, then you need a richer pilot jet.

Those are the outer limits on pilot jets.

[jdrouin]

Next time I have it off I'll take a better look inside.

Just to be clear, I'm talking about the grommet on the *outside* of the plunger base. The plunger passes through the grommet, which is attached to a lip on the carb. You don't need to take anything apart to tell whether the grommet has come loose.

I found a picture on the web and attached it here, with the grommet circled in yellow.

Jeff

[AgentX]

Thanks for the clarification, Jeff.  That rubber is fine on my carb.  Almost disappointing, because it would have accounted for a couple of things.

Ace, I'll check the jets I have.   The numbers seem somewhat arbitrary, as the sizes look pretty inconsistent.  I may have a narrower 25 jet in the box than the one I have on there now, and I'll look for the next size down.

[AgentX]

Could bad ignition timing settings cause carbs to spit back?

[baird4444]

check to see that your points have not closed up either by slipping their setting or wear on the rub block....

[AgentX]

The gap is good and I thought the timing had been set by ping testing, but I started hearing a little rattle going uphill at just over half throttle on my ride into work yesterday.  Just retarded it a tiny bit and we'll see how it goes tomorrow.

[ace.cafe]

Double check your pushrod adjustments, to be sure that they are not too tight.
Adjust them when the engine is cold, and have no perceptible up/down play, but NEVER too tight. They should easily spin with finger spinning when cold.

The mechanics in India are notorious for setting pushrod adjustment too tight, in an effort to make the bike quieter. This is VERY bad and should NEVER be done.

Too-tight adjustment of the pushrods can cause this kind of spitting back, in some cases. I'm not saying it IS causing it in your engine, but it should be checked, especially if any Indian mechanic had his hands on it.

[AgentX]

Hm, I adjusted them about 200 miles ago myself but will check tomorrow morning. Engine's still pretty new so maybe stuff's still wearing in quickly.

[Arizoni]

You didn't frinkle with the cam timing did you?

If the intake is opening too soon that could cause some spitting from the carb.

[ace.cafe]

You didn't frinkle with the cam timing did you?

If the intake is opening too soon that could cause some spitting from the carb.

Even the stock Bullets open the intake too soon.  But if you buy a used Bullet that has been around the block in India, there's no telling what's been done to it.

[AgentX]

Pushrods were perfect.

Engine was assembled here in India by one of those "mechanics," but when I spoke to him about the engine we even discussed how the timing marks were supposed to be oriented.  Haven't opened the timing cover myself to check it out, but since there's no other performance-based additions to the engine I would doubt that's the problem.

I retarded the timing a hair.  I am still, it seems, unable to clearly differentiate ping from the normal valve noise.  Someone else described it as something like the sound of a ball-point pen clicking rapidly, but I'm also thinking that's what my valves sound like at high RPM. 

What I suspected was ping sounded like a small rattlesnake somewhere on my rockerbox.  Not clearly audible unless you were paying particular attention to the engine sound, and although it seemed to stop when you let off throttle, it was very rhythmic.  Is this just the sound of my valves?

[jartist]

I've had my uce ping briefly a couple times in very specific circumstances and it sounded just like the ping of a small japanese four banger.

[AgentX]

I've had my uce ping briefly a couple times in very specific circumstances and it sounded just like the ping of a small japanese four banger.

Thanks--alas I have no frame of reference for that.

[ace.cafe]

Pushrods were perfect.

Engine was assembled here in India by one of those "mechanics," but when I spoke to him about the engine we even discussed how the timing marks were supposed to be oriented.  Haven't opened the timing cover myself to check it out, but since there's no other performance-based additions to the engine I would doubt that's the problem.

I retarded the timing a hair.  I am still, it seems, unable to clearly differentiate ping from the normal valve noise.  Someone else described it as something like the sound of a ball-point pen clicking rapidly, but I'm also thinking that's what my valves sound like at high RPM. 

What I suspected was ping sounded like a small rattlesnake somewhere on my rockerbox.  Not clearly audible unless you were paying particular attention to the engine sound, and although it seemed to stop when you let off throttle, it was very rhythmic.  Is this just the sound of my valves?

Regarding the ping noise, you can differentiate it by when it happens.
The valve/tappet noise is always there.
The ping noise is only there under loads with the throttle open further than normal, such as on hills at rpms below 3500, or exceptionally hard acceleration, or lugging the engine.

The ping will go away if you back off the throttle when you are hearing it.
The valve noise will not go away.

[AgentX]

Thanks, Tom-

The disappearance when I've backed off throttle is what's made me consider it ping; I just started to think maybe it was just how the valves sounded at a certain RPM.  It's kind of hard to separate all the sounds.

What I could use is a relative idea of how loud the noise is...the sound I hear you really need to listen for, whereas when someone says "ping" I imagine a noise that would make me say "What the HELL was that??"

[ace.cafe]

Ping does not have any harmonious timing with the engine noises.
The ping is just randomly occurring metallic clicking noises that do not coincide at all with any engine noises or rpm speed.
It's like as if your keys were rattling and jiggling against the handlebars or something, only under hard load conditions. That kind of noise.

[baird4444]

Ping sounds like to me if you dropped a piece of peagravel into an old galvanized
bucket.....
did you check your point gap yet?

[AgentX]

The gap is good

Yup, thanks.

I feel silly asking, but can anyone comment on the volume of pinging, rather than how it sounds?  Is it clearly audible as you're riding along, or do you generally need to be paying attention to hear it?

[LarsBloodbeard]

It may not be real loud with all the wind/road noise and your helmet on, but it should be noticeable.

Here's a couple examples I found on youtube.  Not the best quality, but if you listen close you can hear it.
http://youtu.be/JA0cH_vRABg
http://youtu.be/VLwM_0k1LRg

[Arizoni]

I kinda like some pea gravel in a coffee can rattle analogy but with a single cylinder it's more like one pea gravel in the can and it often happens at about the same frequency as the thumps of the exhaust.