Am I missing something?

[Gabezube]

Hey there guys, its been a while but I'm back with another question.

2002 Vmax 1200, seems to run decent, but has a slight misfire from cylinder 2 when holding rpms at ~3k.

Ive had the carbs off several times and cannot seem to find anything obvious that would cause this.

In my search, I found a video on youtube of this gentleman showing how he can unplug a cylinder and the bike would continue to run. This got me thinking I might be able to troubleshoot further by trying this.

What i found is that i can unplug cylinders 1 and 3 simultaniously and there is next to no change on the runability of my bike. No more or less hisitation and no change in engine tone. This now has me more stumped than before.

Ive always thought my bike ran decent with the exception of a slight miss when your above idle speeds.

Ill post my link to the videos on imgur. Any help would be greatly appreciated..

Vmax idle

 

[02GF74]

it'll run better if all 4 cylinders are firing.

surely an easy test is to check the temperature of the headers? if you don't have a thermometer, then spraying a few drops of water and comparing how quickly they evaporate would be a very rough guide?

if you find 1 & 3 (front 2) aren't firing, then next step is to check for a spark.

 

[Gabezube]

it'll run better if all 4 cylinders are firing.

surely an easy test is to check the temperature of the headers? if you don't have a thermometer, then spraying a few drops of water and comparing how quickly they evaporate would be a very rough guide?

if you find 1 & 3 (front 2) aren't firing, then next step is to check for a spark.

Correct, the next video in that link is cylinder 3 running with the plug pulled and grounded. The spark plug is firing very well and looks strong.

 

[02GF74]

Ive had the carbs off several times and cannot seem to find anything obvious that would cause this.

What does that mean? Did you take the jet block off, remove the pilot jet and the other jet to see if the holes through then are clear?

It sounds like you have a spark, therefore look for a fuelling issue.

Also is fuel getting to the carb bowls - easy test is to undo the drain screw on each carb.
Is float set correctly and float needle working?
How clean is the fuel filter? (if there is any signs of rust in the tank, and sadly rusty tanks are common, then particles of rust will get into the fuel system)

 

[Gabezube]

What does that mean? Did you take the jet block off, remove the pilot jet and the other jet to see if the holes through then are clear?

It sounds like you have a spark, therefore look for a fuelling issue.

Also is fuel getting to the carb bowls - easy test is to undo the drain screw on each carb.
Is float set correctly and float needle working?
How clean is the fuel filter? (if there is any signs of rust in the tank, and sadly rusty tanks are common, then particles of rust will get into the fuel system)

Yes I have, I've had every carb separated and completely disassembled, all the jets replaced and a/f mix screws replaced.

Honestly I probable need to go through them again, I had the battery die on me and it sat for about 1.5 months without running it.

When I first got the bike it did have a bit of rust in that tank. I was able to do the vinegar and chain method and had it pretty clean, since then I generally always have the tank full.

My general concern with this is I have a dud cylinder mechanically. I had intended on going through the carbs any ways, it just kind of through me for a loop when I was able to pull the cylinders on ones I thought I didn't have a problem with. Maybe my whole carb set up is completely out of tune now.

 

[Jack Hammer]

Easy way to check for a mechanically bad cylinder is to test for compression. Either with a gauge or with a finger.