I have a Kawasaki 19 HP FH601V CS13. (Actually, it's more like a 23 HP because I had the throttle shaft modified!) Anyhow, it ran fine Wednesday morning but Thursday morning it would not start. It cranked for awhile, popped once or twice then the battery died. I charged the battery and tried again but it wouldn't start. So, I got a new battery, new air filter and new spark plugs and it started better than it has for a long time. Better than ever!? When I changed the plugs, I saw the ones I took out were BPR4ES and the ones the dealer gave me are BPR5ES. What is the difference between these plugs? partstree.com and repairclinic.com both seem to say the BPR5ES is correct but other sites say BPR4ES. Is the BPR5ES "hotter"? Is that why it started better? Also, one of the old plugs was wet with either gas or oil when I took it out. It that significant?