spark plugs fouled

[Greenatthis]

Ok. My tiger cub with a 23hp kawasaki seem to loose a little power on our last outing, so I changed the plugs Monday night. We started it up and it ran great. Took the mower out again, ran it for an hour and the plugs are already fouled. Any suggestions on what the problem might be?

[Restrorob]

Is the choke opening completely back up after start-up ? Read the top thread in this forum.

[Greenatthis]

It's an 04 Scags Tiger Cub, FH680v (23 HP Kawasaki), with a 52in advantage deck. We tried a new set of plugs again today, with the same results. Fouled after about an hour. We also use premium gas. Last oil change was about 10 hours ago. I think the choke is opening back up, it seems to run fine after we replace the plugs. any suggestions?

[MowerMedic77]

Have you replaced the Air filter/pre filter and has this unit had any valve adjustments since 04? Kawasaki recommends every 300hrs as regular maint. also what spark plug are you using I am finding this makes a big difference in performance they recommend NGK BPR4ES with an air gap of .030".
P.S. the valve clearance cold for this engine is .004"-.006".
Hope this helps:)

[Restrorob]

If you just recently replaced the air filter the Service Bulletin below may apply. The after-market company we get air filters from states their filter will replace both Kaw's but I found out differently. Note where the vent pipe comes out of the top and identify if you have the three screw plate on top or not. Then check the part numbers for the correct filter and double check the choke. Check into this before we go much further.

[Greenatthis]

Well, the air filter seems to be the culprit. We did our regular maintainence this past weekend (1st of the month) and we changed the air filter. Thanks for all the responses. It seems the engine was "searching" for air. It pulled it from every place possible including the crankcase. Along with the air from the crankcase, oil was sucked in. This is what fouled the plugs.

Thanks again.

Foy