ocd has a great post here which shows the stator stupidty...I have a 96 Superjet. The ski has been lovingly maintained, but would bog after 30 minutes...you could set your watch-it would stop hitting, then run...raggedly, but never stalled. The problem was gradual until it became constant. Fuel pressure OK. Carbs...rebuilt....fuel pump....rebuilt....all lines, valves, one way, etc, replaced..temp sensor replaced..still started easily, ran great till hot, and poop......finally decided it was time to replace the 20 year old crank seals, so got an SBT shortblock (hold the flames please, ski is stock, sbt was good to do business with and the engine is solid) and sure enough, ran better, till a half hour and poop. The only part of the ski not rebuilt was the stator...Jet Ski Solutions did the wiring harness, but their test and ours showed the stator in tolerance and to be fair, JSS only tests at room temp and they tell you that.
With great gnashing of teeth, took flywheel off (lots easier with engine out, but oh well) replaced Stator, end of all problems -- The Cause of the problem was once the stator got hot it went out of tolerance, and was no longer charging the coil properly-once hot, resistance changed, and voltage dropped, knocking the whole system of whack. OCD has a great post where he heats the stator and it goes out of tolerance. We were able to show it as well in my case...we took the stator, ran it to 250 degrees in the oven, and boom ! way out of tolerance. Visually, the new stator was snow white, and mine was a dead leaf brown...
Other than the fact the stator is work to get to, it's not too expensive and still available OE. (jetmanic, of course)
Three seasons and 150-200 gallons later, thanks to this forum (jetmaniac spotted my dead stator visually from some posted photos, no less !!!) for all the help, and ski runs great.
Here's the prior thread - you can see I had a lot of friends here help out.
---TL DR excerpt----
The new-in-a-bag Yam stator tested at 540 ohm.
Spec, per the manual, is 497.7 to 608.3
The old Yam stator tested at 528 ohms-JSS was correct in "tested OK" and they state they don't temperature test.
The new coil was a snowball white, while the old coil has some discoloration. I intend to unwind it to verify insulation failure. In the future, a visible discoloration may be a fail symptom....
To check the coil, it was placed in the oven....and run up to 300 or so degrees, slowly, as to mimic what happens with the engine.
At 265 measured degrees, the coil resistance went up to 718 ohms. As it cooled, the resistance dropped. After a minute it was down to 695, and continued to drop as the coil cooled.
This "in spec" while cold but "out of spec" when hot is the same thing OCD showed in a post where he set up his ignition test rig, the coil fired OK at room temp, until he warmed it to 180 degrees using a heat gun, where the output voltage of the coil then dropped enough not to fire the CDI and plugs properly. This is exactly the same thing (ohm's law) we observed, even though we were testing resistance and he was measuring output voltage. The increase in resistance would decrease the output....and the 20% change agrees with his experiment.
http://www.x-h2o.com/index.php?threads/twenty-years-on-one-engine-sorta.184018/#post-1939334
