Cylinder 3 wont fire... at a complete loss

[Schming]

Fuel is getting into the bowl, and it doesn't seem that the float is sticking. I checked the gasket and its all nice and trimmed flush. Maybe the float height is off...? Though it seems (visually) equal to the others...

You may need to measure the float heights cause just looking at them isn't accurate enough

[sethhope]

You may need to measure the float heights cause just looking at them isn't accurate enough

How would I go about accurately measuring the float heights?

[sethhope]

Just a thought... when i checked spark, it seemed solid to me, but is there any way that it would spark OUTSIDE the engine, but not when i put the plug back in?

[Schming]

How would I go about accurately measuring the float heights?

check this tutorial out;

http://www.xs11.com/forum/showthread.php?t=76

[motoman]

Update. I soaked the carbs again. This time a full disassembly. The floats float and the pin isnt getting stuck. The diaphragm is beautiful as well as pretty much the whole carb assembly. I pulled the jets and sprayed them out with cleaner and compressed air. Put everything together and still nothing on 3... im at a complete loss... it pops and sputters, but never heats up. Good spark, clean carbs... pardon my frustration but WHAT'S GOING ON HERE???

#1...... Float height being a visual thing is NOT gonna work. Even your eyes are not good enough to see a 1/2 millimeter difference.
#2......If you removed the pilot jets and failed to blow compressed air through them from the top-side where teeny atomizing hole is, they are NOT clean. If you don't believe me, get a magnifying glass with a LED light attached and look at internals of pilot jets. Internals of them are larger and easily trap even the tinyest piece of forgien matter that CANNOT be blown out from bottom side of these jets......just doesn't work period. If you see something trapped inside pilot jets, a paper clip straightened out will fish it out.....blowing compressed air won't. What happens is that teeny piece of foreign matter gets stuck up against the teeny metering hole from that being direction of fuel flow. NOW, you know why 'triple clean' is always stated. Along with that while pilot jets are out, use a round pointed toothpick and reem them a bit in ALL the side holes in order to properly clean them. Idea is to ACTUALLY eliminate any possible issues whether they are one or not before moving on.

[MaximPhil]

I did do a compression check and it read 120 on the nose. As for the help, i really appreciate the offer, but im a bit further out than my profile says. I dodnt get to changing that last night. Im actually closer to philly pa...

Hi Seth,
You are lucky to be within range of Eastcoaster.
He has resurrected some real basket case XS11's
With his help your XS will soon be sitting up and begging to be ridden
Phil

[CaptonZap]

Just a thought... when i checked spark, it seemed solid to me, but is there any way that it would spark OUTSIDE the engine, but not when i put the plug back in?

Yes, the plug will spark at a lower voltage in ambient air. To see if your coils are good, break the ground electrode off of an old plug, lay the plug on the engine, and crank the starter for a few revs. If you see the spark jump from the center electrode to the outer shell of the plug, without a miss, and a good blue spark, the coil is good.
Magneto's are tested with a quarter inch air gap as a standard test, and a good coil will produce the same voltages, thus the same gap jumping ability.

CZ

[motoman]

Just to verify, the carbs start dry and when you put them on the bike, the bowl fills like you are describing? Is the float filled with gas? if so, could be sinking and allowing fuel to fill the bowl, then raising back up in a full bowl and cutting off the flow. You have the brass floats, correct? I don't know if that makes sense, but I am just putting ideas out there.

Fuel bowl, if filling okay has absolutely nothing to do with whether fuel is being metered through pilot jet or not.

[Bonz]

To recap what I said, I am not quite sure what the heck I said? I was between teaching classes when I typed that.

Moral of that is.... "Friends don't let friends teach and then forum during the passing period".

My only saving grace is to suggest that if the bowl was totally full, and the needle seated hard against the seat, could the engine pull fuel from the pilot circuit without any opening on the back end of the system? Like sucking on a glass coca-cola bottle sitting upright with your mouth and expecting to bring soda up.

[nzemke]

Does it idle strong? Or choppy? The diaphragm is easy to check, lift it to the top and hold your thumb over the air vent that goes to it. The diaphragm will slowly lower. It doesn't sound like that's your issue but now you know. If it had a crack or improper install issue then you would see it just drop, it will start slow then have a quick drop then keep going slow to its resting point. A trick my dad likes to do is take out the spark plug and set it on the block so it doesn't hurt the coil. And hold your hand over the spark plug hole. Turn her over and you should feel moisture on your hand. What color is your plug? Can you post a pic? Also have you checked to see if the air/gas mixture screw tip is broken off?

[motoman]

To recap what I said, I am not quite sure what the heck I said? I was between teaching classes when I typed that.

Moral of that is.... "Friends don't let friends teach and then forum during the passing period".

My only saving grace is to suggest that if the bowl was totally full, and the needle seated hard against the seat, could the engine pull fuel from the pilot circuit without any opening on the back end of the system? Like sucking on a glass coca-cola bottle sitting upright with your mouth and expecting to bring soda up.

Yep...it should......BTW, that was two different unasociated scenarios, at least as far as carb function anyways. Now as far as sucking on a full Coca-Cola bottle.....if that were Sprite instead, it would likely work fine.

[sethhope]

Thanks for all the input guys. I took the carbs apart... again... didnt have time to check float heights at the moment, so I'll do that when i get back. As for all the holes, jets, and passageways, they are all clear and clean (air through both sides, paperclip where necessary). Diaphram seems almost new. Ill get a pic soon, but the plug is a nice dull grey on the electrodes, and a smooth caramel and white color on the ceramic.

Guess when i get back, im checking the mixture screw, float height, and whether I'm getting "mist" from the open plug hole. Am i missing anything before i tear down again?

[sethhope]

Plug from cylinder 3

[motoman]

Plug from cylinder 3

Not bad.......a bump on the rich side.
What you normally find with the pump fuel now having a tad of alcohol in it is with a proper burn air/fuel ratio, the plugs will closely resemble what they looked like when new out of the box. The plug color like I was used to seeing several decades ago before added alcohol is not the case anymore. So, with that, and the visual of the plug looking close to what its color would have been decades past, NOW make the visual you've shown a bit on the rich side.

Also, the idle mixture settings affect plug color through ALL rpm ranges, not just at idle or entirely in the idle circuit up to approx. 3,000rpm. When the idle jet reaches max. flow based on rpm and cyl. vacuum draw, the main circuit larger jet ADDS to the fuel necessary to accommodate rpm increase. In other words, idle jet and pilot circuit are ADDED to, not shut off by some magic.

[sethhope]

Not shut off by magic...? WELL CAN SOMEONE EXPLAIN WHAT MAGIC IT DOES RUN ON? I took a day off from working on the bike and suddenly she runs like a clock... whats going on here, and should i worry about it cutting out again?