Partial throttle issues

[matt87]

Ok, so my bike has run rough ever since I've had it so I finally bit the bullet and bought some emulsion tubes. I put them in along with cleaning the carbs and syncing them. I was also going to tune them by header temp and for the most part I did. Cylinders 1,3,4 were tuned to around 350-375 however cylinder 2 doesnt reach above 150 and its probably only getting there by coolant heat. I know it does fire because in the upper rpms the thing is a beast and partial throttle acceleration is fine for the most part as well but when crusing it is obvious that the cylinder is not firing. My question is what could be causing this; a dead cylinder, no spark for only partial throttle w/ no load, or maybe the cylinder getting too much fuel at low rpm? I did turn the mixture screw on the 2nd cylinder all the way in to try and lean it out. Any help is appriciated. Thanks.

[DEMORAL1ZE]

sounds like a coil problem/plug wire problem...............

[the_finch]

I'm far from an expert but have you checked to see that your idle jet on that cylinder isn't clogged?

[reelrazor]

Lean misfire, or rich misfire at that throttle position. How's #2 spark plug look? Aaand, how is that diaphragm in the #2 carb?(possible slide not lifting at low-load cruise vacuum due to pinhole-but responds to big throttle position changes/vacuum inputs)

[matt87]

Well hopefully I can get a chance to look at it today after work but the diaphram in carb 2 looked fine. The carbs looked to be pretty good actually since this is the second time ive had them apart to clean them. I will try and get a picture up of the spark plug today or tomorrow. That might be a little more help. Can a coil go bad and only effect one cylinder?

[reelrazor]

Well hopefully I can get a chance to look at it today after work but the diaphram in carb 2 looked fine. The carbs looked to be pretty good actually since this is the second time ive had them apart to clean them. I will try and get a picture up of the spark plug today or tomorrow. That might be a little more help.

Okay, BEFORE you put the emulsion tubes in..when it "run rough ever since I've had it"...was it running on all four at least?

Can a coil go bad and only effect one cylinder?

No, the coil itself cannot fail and cause fire on only one of it's outputs. The plug lead and plug cap however CAN go bad causing one cylinder of the coil's pair to not spark.

[josbourn1]

i had a similar problem with my old kawasaki. the carbs were rebuilt by a shop and there were small plugs in the bowl for the pilot jets. well one was never put back in and it caused the carb to suck fuel through the air venturi and richened too much. so much fuel running through caused a much cooler header and would foul plugs daily.