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Motorcycle Repair/Cbx 1000 1979 Not firing



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.

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.

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?

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Jan Ringnalda


PLEASE NOTE: PLEASE READ THIS!!! I can help with questions ONLY on any Honda CBX-1000 motorcycle, only 1978 to 1982. OR 1981 to 1983 Honda CB1100R models ONLY Honda CBX/CB1100R motorcycles, Please NO other makes, no other models. IF YOUR QUESTION IS FOR ANY OTHER BIKE Your question MAY BE FORWARDED TO THE QUESTION POOL WHERE IT MAY NEVER BE ANSWERED. IF I ANSWERED YOUR QUESTION, and you feel the need to give me marks lower than 10, first post a follow up question. If you mark me lower, I will respond and you run the risk I will never, ever, answer one of your questions again. I'm doing this free of charge, as a service to fellow motorcyclists. If you do not value my time, I do...


Have owned over 50 of these fine classic Honda motorcycles

International CBX Owners Association, SAE, Materials Research Society

CBXPress, VLMC magazine, Used Bike Guide

PhD in Materials Science, Post-Doc in prototyping automotive components

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