cylinder #3 is cold

[tab1324]

I put the bike back together with the stock airbox today and tried to fire it up. This carb rebuild seemed to eliminate the backfiring I was experiencing and is a big improvement over the last time... But, I can't get it to stay running still. It starts and runs for about 30 seconds or so and then quits. I've got the butterflies closed and the idle mixture screw about 1 1/2 turns out. Haven't had time to experiment with different settings too much but after a few minutes of trying it this way, I noticed a bit of smoke out the left exhaust pipe. I then felt each exhaust pipe at the head and 1 & 2 were warm, 3 was cold and 4 was barely luke warm. I pulled plugs and noticed better looking plugs than before but still seems too rich. My question is - why would cylinder #3 be bone cold.? No sign of gas in the cylinder but the plug had some on it and looked like it is firing. I had previously checked for spark at all 4 and it was there.

HELP! I'm worried about cylinder #3!

Tom B.

[Dennyz]

Here are some ideas:

-If you have another plug, change #3. It could be fouled.
-Swap #2 & #3 plug wires. If the problem moves to #2, you could have a bad coil wire.
-If you have the air box off, squirt fuel into #3. If it fires up, it is a fuel problem.
-A compression test will tell you if you have a valve or ring problem.

Good Luck!