Front Cylinder Won't Fire - 2007 HPX - Gasoline

[rralexander]

I recently purchased a 2007 HPX 4x4 with the 620cc Kawasaki gasoline engine. It had 186 hours on it and ran great for about 5 hours before losing half its power. I soon realized that the front cylinder was not firing. I checked the compression and it is fine. I swapped the plug with a new one and still nothing. It appears to spark, but I was told by a mechanic that that is no indication it actually will fire under stress. He suggested I change out the coil on that cylinder (as you know there is a coil for each of the cylinders). I changed it with a new coil and still it won't fire (so much for the $80 I spent on a new coil). It appears to be getting gas because after driving it around a while (at half power - the back cylinder runs like a champ) and when I pull the plug it is wet. I'm at a loss for what else could be going on. Any help would be greatly appreciated - thanks, Ryan

[Dane]

Did you replace the spark plug wire when you did the coil?

[rralexander]

No, the new coil didn't come with a new spark plug wire, so I pulled the wire off the old coil and used it. I figured the wire would be ok. Was that not a good assumption?

[Dane]

If you've got compression and fuel the only thing left is spark and with a new plug and coil the wire is about the only old thing left, and they can and do go bad.

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Long ago I had repeated problems with one cylinder of a Kawasaki twin in a LX188 not firing. A new plug would fix it but after a few hours running the plug would be dead again. After three new plugs on that one problem cylinder I finally broke down and installed a new plug in both cylinders at the same time and it ran fine for years. I don't know if the two plugs failing was related or just coincidence.

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Spark plugs are odd things. For aircraft spark plugs there is a rig that test them under pressure. It has a window to observe the plug firing as you turn up the air pressure. Most plugs fire fine at normal pressure but old or damaged ones stop firing when when cranked up to 100 psi.

[rralexander]

Thanks. I'll give replacing the spark plug wire a try and let you know what comes of it.

[fastone110]

I'm having a similar problem now. Back cylinder runs fine. I have spark on the front cylinder via watching the plug rest on the engine. It appears it's not getting fuel so I'm rebuilding it this week.

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