Most of your new style spark plugs are resistor type and have a very fine spark. When you say weak is it yellow or white arcs? If it is a skinney blue/orange spark it is fine you have other problems. Also is it firing across the end or across to the side where the threads are? If it is not arcing across the electrode then its probably fouled out, esp if its a NGK plug. I am thinking it is a NGK plug BPR5ES, this is a resistor plug, hince the R in the number, non resistor would be BP5ES and would have a fat blue/orange spark at the electrode.

Also we need the type of the engine to help you out. This engine could have a 1 piece ignition ie coil only or 2 piece, ie coil and ignitor setup.

The type is what will help us determine which system you have.

here is the same coil that i have on my mower.

oops sorry i didn't put in the link.
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=140418765102&ssPageName=STRK:MEWAX:IT

the plug that came in the motor when i bought it is a BM4A and the new one is a BMPR4A.

Yes, my bad...

I don't know why I typed BPR5ES, that is for the overhead valve engines. duh...

The R in the BMPR4A is for resistor and will have a fine arc across the electrode. BM4A is non resistored.

By the picture you have a 2 piece ign, the coil and the little box on the end of the wire is a ignitor, whick performs the same function as a set of points and condensor.

This version is harder to test, you need a spare "good" ignitor to try first, they are not cheap to buy new just to try. I kept one in my box to loan out for this occasion. Ignitors fail most of the time, but sometimes its the coil. I am not aware of a way to test the ignitor with a volt/ohm meter.

You want to seek out some help for a shop that works on the Kawi for proper diagnose of the problem.

The FB460 is a single stage coil module ignition, 12.5HP. Advance carries the non-resistor NGK's, I use them in my two Pentons since they both have Motoplat ignitions.

Engine will run just fine on either resistor or non resistor plug. Champion CJ14 works also.

If you go to Kawasaki's or JD's site's you will find a coil and ignitor ignition system listed.

JD used the split systems on RX/SX95's, 160's and 112L's to name a few.

It's most likely the ignitor (small silver square box on the side of the engine).

On the coil there is a metal tab that grounds itself to its mounting bracket. on my coil the tab was broken off or rusted away so i soldiered a wire to the little nub and grounded it to the bolt and i now have spark! thanks for the help