Not running on all cylinders

Just a little backround. I just purchased an xj700 maxim with 12, 700 miles on it. I have replaced the plugs,oil,filter,etc. My far left cyclinder when starting does not want to spark. If I take the plug wire off and put it on just a little without it making complete contact it will arc to the top of the plug and allow it to start fireing. I let it run like that for a couple of minutes then put the plugwire all the way on. I took the bike for its first ride tonight after that and it ran great... I mean I never rode a brand new one but wow these xj700's are really fast, at least to me lol. I was hoping if this problem continues you guys might have some suggestions on what the problem could be. p.s. The plug wires look good and fit nice and tight on the plugs.

 

This may be a simple matter of the plug wire being burned where it connects to the plug cap. I would remove the plug cap and cut about a half inch off the plug wire then reattach the cap. It is real common for these bikes to have a burned plug wire after this many years.

 

Your plug was fouled for some reason (or maybe defective).

When you had the plug wire on tight something was bleeding off the spark before enough voltage built to jump the spark plug gap. When you pull the cap loose you push the resistance way up - allowing the voltage to build and thus jump the plug gap and the gap where the cap was loose.

Then as it runs it either:

A) Burns the fouling off

B) Plug gets hot closing off the flaw in the ceramic.

If it fires right up next time you know the plug was fouled. If not, replace the plug.

 

These bikes have 2 inherent problems. The coils have a tendancy to have minor cracks troughout the casings and the solid copper core wires corrode really bad and contain a resistor cap thus having a spark problem. I converted mine over to an automotive carbon core style wire with no resistor caps. I use the carbon core for the corrosion factor, it has no other advantage. I have a blog on what I did to convert it over to this set up. I have been running it this way for over a year and have had no problems with it. It made all the difference in wet weather riding also.

 

Where is said blog?

 

http://xjbikes.com/Blogs/mode=display/id=52.html

 

i had an old bultaco that had the same problem every thing was replaced the coil, plug wire exc. it turned out i had a faulty plug try switching some of your plug around, might save you some money before you start replacing parts like i did.