Opinions on Cause of non-firing

[Espiritus]

Hey, all. I have gotten the carbs out of the kitchen and reinstalled, only to find the #2 still not firing. It IS getting gas as there is gas in the float bowl and there is spark. Just no firing.

Is it possible that there is a connection between this non-firing carb, and the non-working in the "on" position petcocks? I know that the vaccum comes off the #2. If the #2 isn't firing, could it cause the problem with the petcocks, and, conversely, could the vaccum line be causing the problem with the #2? I read somewhere that someone had to reset the idle/mix by "seating it" then backing it off 1.5 turns. Is this something I should explore?

Finally, I have 4-1 Kerkers (old). What kind of gaskets do I need? I don't think the ones that I ordered were the right ones as they merely sat on the ends of the pipe and kept the pipe from going into the hole. Was this right or do I need to reorder a correct gasket?

Inquiring minds want to know! By the way, my 16-year old son was very impressed when I shorted the sparkplug to see if it would "spark" but he stood W A Y back when I got ready to start the bike for the first time after putting it back together. We had a day-long "bonding" to put it together, clean the engine, paint the pipes, reset the pipes, rehook all the fuel/vaccum lines. . .he didn't notice that I had failed to turn on the key when I couldn't get it to start. . .then I "discovered" the problem and acted like it was a big deal . . .

Hard to impress kids these days

Cam

[trbig]

Well... Normal things. Do a compression check. You said you checked for a spark on the #2... did you get a good strong one? If not, you could need a new plug, or the cable trimmed up just a bit and boot re-installed. One coil runs #2 and #3 so if 3 is firing, it's not the coil.

If you have compression and spark, then it's fuel. Just because there's fuel in the bowls, it doesn't mean it's getting past a possibly plugged enrichener circuit or pilot jet. I realize you just cleaned them, but it's been found that sometimes people don't get everything cleaned out as well as they'd hoped.

I wouldn't blame the petcock if it's only one cylinder not firing. If that were a problem, there'd be two of them not firing.

It's just a process of elimination... Good luck.


Tod

[boyat68]

Espiritus:

You have to start your synchronization process. When the carbs are clean, often the butterflies are not all opening at the same rate. You can diddle with each screw, one at a time and try to get them set by ear, but with 4 carbs it is difficult. Invariably one carb will not pull fuel the same as the others and will be cold upon startup and will be noticeably colder than the rest. Some on this site espouse the bread-tie method of presetting the butterflies as a starting point, others say that you should open each butterfly just so the first hole of the 3 hole port in the bottom of the carb throat is uncovered as a starting point. There is a good "How to" thread in the maintenance section. In any case the idle Pilot screws should be set 1-1/4 to 1-1/2 turns out from a lightly seated position before you start the synchronization process.

You did check the idle Pilot screws when you had the carbs apart to ensure that they all work and no point was broken off and stuck in the air hole?

You do need some method to read the setting of the carbs, either a set of gauges or a set of carb sticks.

For the time being you can experiment with opening that #2 carb's butterfly just a tad to see if you get conbustion. This can be evidenced by the spray on water method.

[prometheus578]

"Ok, several things to check..."

... carb synchronization would be one of them, but let's check a few others first.
A vacuum leak will stop the carb from drawing fuel at idle:
Yes, the ignition timing is activated through the vacuum line from #2 carb. this line plugs into the carb, not the manifold boot, like the other lines. Check that this line doesn't have any holes in it... yes, remove the left side engine cover and check the line down in there.
If there's any question of vacuum from the line to the petcock... Hook the petcock vacuum line to #1 carb and see if the problem switches to that cylinder.

I read somewhere that someone had to reset the idle/mix by "seating it" then backing it off 1.5 turns. Is this something I should explore?

For some reason, this tells me that you didn't remove the pilot screws when cleaning the carbs.. is this correct?
Had you removed them, you would have had to "reseat them" as mentioned.
Not so much the reseating thing... as it's an adjustment, but...
Oft' times, someone, usually the previous owner, has tried to adjust the idle mixture and tightened down the screw too far. this results in the tip breaking off and pulling the hole, as Boyat68 intones. Plugged hole.. no fuel for idle. Common occurrance... I suggest removing the carbs, removing the pilot screw and springs and checking the tips of all screws. They should be sharp and pointy. If #2's isn't, then chances are the tip is broken off and lodged in the hole.
A broken tip will only affect the bike at idle...the carb will supply fuel once past that stage.
You could take the bike for a quick run around the block to heat the pipes up. Yes, it'll run a little ragged, but it's runable.
Once back home, take a spray bottle of water, or a bottle of 409 cleaner and spray the exhaust pipes coming out of the engine.
If they all "sizzle" the same, that means that they are all getting fuel. If #2 sizzles differently, that mean not only is it not getting fuel at idle, but it also isn't geting fuel during it's other stages and further things should be looked at.
Don't know where you got your exhaust gaskets... here's a link to Z1 for exhaust gaskets.
http://www.z1enterprises.com/catalog...S1100-1978-GA0

[dbeardslee]

Cam - The other thing to check is your plug wires and caps. Do you still have the factory coils and wires installed? One of the first things I did when I got my XS was to get rid of the old coils in favor of the Mikes XS coils, along with new wires and caps - HUGE improvement. I was going to put the old ones in coffee-can-storage, but when I bent the high tension wires to put them in the can they broke in two. Looked OK from the outside, but inside they were gone.

There's a post on here somewhere that details grafting new high tension wires into factory coils, which is the cheap route. I opted for the hotter coils for the hotter spark and to get rid of the ballast resistor.

That being said, I've gotta agree with boyat68 and Trbig. Lots of people have had to clean their carbs three or four times (myself included) before the carbs are really clean. Pay particular attention to the small orifices at the bottom of the float bowl - that's where all the garbage settles. If you stick the nozzle tube of a can of carb cleaner right in the hole at the bottom and push the button, you should get a fine spray from the hole up close to the lip. If it spits or tries to come out the hole you have the tube in it isn't clean. A small piece of wire poked in the holes can remedy. Any time you take the carbs off you really need to resynch. Out of synch carbs can really make them run crazy.

Prom - You're too fast for me. Must have been typing at the same time. Always good advice from Prometheus.