1 st cylinder dont fire

Hello,
The first cylinder dont work. The bike run on 3 cylinders.
carb is clean. I can see a spark from the spark plug when i test it. The spark plug have oil but no sign of start.
I suppose a worn valve guide because of the oil on the spark plug.
but can this cause a missfire ?
i think the spark plug would be black an fouled and not new and oiled …
The coils have 4 years. Dyna green.
to test the coils can i use a old kaw one mixed with a dyna one ?

best
f

Yes you can mix the coils to test as long as they are the same resistance (3-4 ohms) oil on the plug will cause a misfire as the voltage will travel to ground through the oil rather than jumping the gap (electricity is lazy)

Burn away the carbon and oil with a gas torch and than clean the spark plug with a brass brush.
 

Ok but i should see some trace of ignition on the spark… i think i can see a little black color but just at the gap. Other than that the spark plug is like new …

Spark, fuel, compression.

If you have spark, the carbs are verified okay, that leaves compression.

Are the valve clearances in spec?  Compression test.

Based on prevailing past history, I'd guess carbs, because many times people think their carbs are clean, however there could be an internal problem with the pilot circuit.

Hello,

just an update to help if someone have this problem :
The spark plug was defective!. Purchased new (ngkb8es) but the spark was not blue and powerfull has other ones.

Note : i'm going to buy a good spark plug tester!
thank you for your help,
Fox

You may have gotten a knock off plug made in China.

I just had a very similar problem, after 10 Miles on my freshly rebuilt 77KZ1000 the engine started running bad, after some diagnosing I found the number 1 and two plugs were not firing.  I replaced them with some old plugs that I knew did work and the bike ran great again. I will replace the two used ones with new ones.
all four of the plugs used in the rebuild were from a NEW 10 pack of NGK B8ES
So this brings up my question, Hardrockminer commented maybe they were Chinese Knockoffs. How do you tell?
They are marked NGK B8ES in a NGK box.




 

Bogie1 wrote:

I just had a very similar problem, after 10 Miles on my freshly rebuilt 77KZ1000 the engine started running bad, after some diagnosing I found the number 1 and two plugs were not firing.  I replaced them with some old plugs that I knew did work and the bike ran great again. I will replace the two used ones with new ones.
all four of the plugs used in the rebuild were from a NEW 10 pack of NGK B8ES
So this brings up my question, Hardrockminer commented maybe they were Chinese Knockoffs. How do you tell?
They are marked NGK B8ES in a NGK box.


 

www.ngkntk.com/newsroom/blog/emea/fake-or-not/