Motorcycle Repair: Cbx 1000 1979 Not firing

Question
QUESTION: Hi Jan

I am hoping you might be able to help or steer me in the right direction.
My No. 6 cylinder does not go bang, even above 4000rpm. Cleaned carbs as per mike nixon's pamphlet, and cleaned No. 6  carb a couple of times.
I have between 85 & 90 psi on all cylinders, cold with throttle and choke open.  I have good spark with  All new spark plugs.  I have also swapped HT lead from 1 to 6 as they are the same coil, and even swapped over the configuration.  I even replaced with another HT lead from another bike.

I tried swapping the jets from 1 to 6, still no change.

I have sprayed "easy start" into the carb also.

The plug is wet when I remove it.

It has been suggested I need to check valve clearances.  I do not know how to do this.

I would appreciate any help you could give me.
Cheers.
Arnie

ANSWER: Easy check, remove #6 spark plug and do a quick compression check.  If compression is there then we have a mystery, but I suspect you have a stuck valve.

Let me know,  Jan

---------- FOLLOW-UP ----------

QUESTION: Thanks for your quick response.

I have 85psi on No.6, similar to the other 5 cylinders.

ANSWER: Well if the plug is wet, it is clearly not firing and getting fuel.  So it has to be between the coil and the plug.  Replace plug with known good, and replace coil with leads.  It sure is a mystery let me know what you find!

---------- FOLLOW-UP ----------

QUESTION: compression is low on No 6 despite originally seeming to be the same as the others, have taken valve cover off and checking clearances, all around .o2 to .o4 mm, so suspect rings.  will have to take head off.  never done this before.
cheers
arnie

Answer
More likely to be a burnt valve or perhaps stuck rings.  What was the reading?  You can check the rings by repeating the compression test after putting a teaspoon (not more) of oil down the cylinder and repeating the test.  If it improves it is a ring problem, if it stays the same it's likely a valve.  The head can come off with the engine in the frame but it is tight...But since the carbs have to come off and you are tilting the motor forward to do that, it's easier to give yourself more room by leaving the engine tilted forward.  What was the history of this problem?