#1 Cylinder cold - 82 Maxim XJ550J

Hi all, looking for advice - I don't know what else to check or change. This may be rather long but I would like to say what I have done so far. ORIGINAL PROBLEM: #1 cylinder cold, not firing. I had foot surgery last year and did not ride, but was running like a top when put away. I checked spark, compression; good. I checked fuel - no fuel in bowl. The float needle was stuck. Cleaned and rebuilt carbs, checked and adjusted valves. Color tune was a nice blue thru out the ranges when checked out Sunday night. Monday morning ride to work - get almost 3 miles down the road and #1 cylinder goes away again! That night ran the colortune again it was pure white in that cylinder. Pulled the plug, it is wet, so getting fuel now. Spark is great, compression is 90. Not sure what else to do so I changed out the coil for #1 and #4. Now #1 STILL does not fire (pipe is cold). #4 is still fine. I am out of ideas... thanks for all advice in advance.

 

Change the plugs around and see if it follows the plug, Check that the mixture screw has the oring and washer and hasn't backed out. Also, make sure the vacuum cap installed on the nipple.

 

Why didn’t you try a new plug?

also, maybe the cap is loose—-
Also, may need to clip the wire back a tiny bit—-

if prop is only on 1, it’s most-likely not the coil. Coil fires 1 AND 4

 

okay, thanks for replies. Sorry, I forgot to mention I did change plugs early on, no difference. I only changed the coil because I had another one and didn't know what else to try. Yes, #4 has not had a problem, it was just another step to try, but it didn't change anything. I have never touched the mixture screws, as it has had a mixture problem, and carb was not a problem until the gas 'varnished' the float seat, I didn't mess with the mixture screws. "Also, make sure the vacuum cap installed on the nipple." Is this also in regards to the mixture screw; I am not sure what you are speaking of... Oh, on top of the intake. I know now what you are talking about, yes, good thing to check. That is on. I had suspected it might be something in the cap area, so I eliminated all that when I put the new coil on; I put the new caps on the new coil wires when installing the new coil. It is strange because it ran so well when I checked it with the color tune, and then for the short time on the road, then it hasn't fired since that I can tell. Many thanks for your input, ideas, and advice. I will go thru things again.

 

Check the continuity of the new plug cap on #1 with an ohm meter. It should read about 10k ohms. If it reads zero, it isn't passing any juice. I had one that read zero, and it would still spark...with color tune. I imagine the voltage from coil was enough to jump gap for a weak spark. Perhaps the new plug cap is defective? Perhaps swap the new plug cap between 1 and another cylinder and see if it follows?

 

Thanks cguts, for your suggestions! #4 cylinder, off the same coil, is fine, but I put a whole new coil/wire/cap assembly on it because I tried and could not remove the cap from the wire on #1 (it was the original coil assembly), and I also then switched plugs. The spark jumps across a 1/4-3/8"" gap on my tester, so I have good spark. I then tried with a brand new plug, no difference. When I turned the mixture screw in the entire way, then just cracked it open, I got a flicker of orange out of the ColorTune, and a bit of warmth on the pipe, so it was starting to fire a few rounds then, but still acting like just too much air. I have ordered parts now to rebuild the throttle shaft seals; when I rebuilt the bottom of the carb I did not replace those. I am grasping at straws, and it is getting rather expensive! To think, the whole problem started when the float needle got stuck in the seat on #1 because I couldn't ride last year and didn't drain the carbs. I had a very orange spark with the ColorTune on #1 before my rebuild. I figured it would be an easy fix...not. Amongst all this, the petcock decided it was done too, so I am waiting on a rebuild kit for that - when it rains, it pours!

 

And, sorry, yes, the new cap read about 11k ohms.