Super Jet 91 Yamaha 650 Superjet running problems

Hello, new here but working on son's 91 Yama 650 Superjet. He started having problems with it not feeling like it was powering up all the way. Then, it started bogging down when it was given full throttle. Next it would not start and after letting it sit for a while, it would start but not much power. Then, not start at all. First, went thru the carbureator and that is not the problem. We sprayed some Mercury engine tuner into the carbureator to get rid of engine carbon build up causing it to back fire, splitting the fiberglass water box which I now have to find and replace. Checked for fire at the spark plug but was not getting any. A friend had a new kawaski ignition coil for an older stand up ski which a mechanic said were basically the same. Put it on and it fired right up and thought it had solved the problem. Lowered the stand up into the water since I live on the lake, fired it up and as it was being powered up to stand up on, it died and would not start. That is where we found water leaking in from the cracked water box. Put it back on the dock and when trying to start it, it started just for a few seconds a couple of times and then would not fire at all. Checked the coil at the spark plug and again there was no fire at all. I think it is probably the CDI or Stator or possibly even the coil but as expensive as oem parts are, thought I would ask if someone might know what the problem could be and if going back with aftermarket parts would be ok since it is a 1991 ski and the oem parts are just too expensive to put in that age of a jet ski. Thanks in advance for anyone help.
 
You should be able to find used stator and either a 6m6 650 or 61x 701 cdi pretty cheap. You can always ohm the stator coils before digging in and pulling the flywheel. Can also ohm out the coil. If the coil is suspect see jetmaniac for a JSS coil. well worth the $$$.
 

Midlake Crisis

Site Supporter
Location
Bakersfield, CA
Here is a good primer on troubleshooting electrical issues. FAQ - Troubleshooting Electrical Issues
Did you try disconnecting the kill switch (black & white wires from switch to eBox)?
The way I understand it the actual coils rarely go bad, but the wires frequently do.
Stock CDIs get blamed a lot but rarely actually go bad - the main cause when they do being cranking the engine over and over without having the spark plug wires connected / grounded.
 

Byeai

"Cheetos-Man"
Location
Melbourne FL
I may have a 6m6 cdi I know I have the stator but have no idea if its good lol I think I got a complete 6m6 ebox

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Ok folks, got it figured out. The ski is running like a top. It was the CDI. Also the carb was cleaned out and adjusted, The low side was adjusted to 1 3/4 turns and the high side to 2 turns. Ran as good as it ever has. I have seen where people have posted in the past that no one evers posts what the problem(s) were , so here it is!
 
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