Super Jet Stumped…need some expertise!

Skirunner24

Skirunner24

Location
WI
All right guys, this problem has been haunting me for the better part of a year now (since I BOUGHT the ski a year ago). I cannot figure out what is going on and have started to run out of ideas. Here are the symptoms: The ski will run great for 15-20 minutes into every surf ride. Suddenly, like clockwork, it will start missing on one cylinder. Not completely missing, but enough to where the drop in performance is obvious. I head back into shore, pull the plugs and the front plug appears fouled. I replace both plugs and she runs great again for the next 15 minutes (sometimes less). At first I thought this was a water ingestion issue and I went about sealing everything I could find that was potentially causing water intrusion. (I had A LOT of problems with my a/m hood sealing). The problem usually seemed to show up after a stab or any maneuver that could cause water intrusion. Yesterday, I finally had everything sealed up well and the issue arose again without any water getting in.

Here are the applicable motor specs:
61x/62T, ADA Head, B pipe, JSS Coil, stock carbs, stock FA…

Misc things I’ve tried for this problem and other non related issues: Rebuilt carbs (with new needle/seat), adjusted carbs – leaned out cylinder that was fouling plugs (to the best of my knowledge), replaced intake mani gasket, replaced head O-rings, replaced stator (with a used one), replaced fuel lines, JSS coil was added by PO because he apparently was having problems running in salt. (I only run in salt at this point).

I should have swapped plug wires to help diagnose, but it didn’t dawn on me to do this until after I was already home.

Short video of the symptom's I'm trying to explain:


Pics of the Plugs:

Rear: (Notice the coloring pattern...only darkened on one side of the plug. Any ideas why?)
evemy7u8.jpg


Front:
vyhave9y.jpg



Thanks for any help guys, I'm sick of troubleshooting this ski!
 
Last edited by a moderator:
Skirunner24

Skirunner24

Location
WI
I actually have a spare one. Bought it when I was troubleshooting a different problem that ended up being the stator. That's probably next on my list...
 
Balduccimoto

Balduccimoto

Location
NYC/Long Island
I think reason why after you change the plugs it runs for a little bit, is bc something may have cooled down, not that the plug was fouled.. Like Mdavies said I would try that spare CDI. The reason why the plugs could look darker on one side is because that side of the spark plug is closer to the exhaust port and runs a little hotter that burns off the carbon.
 
P

phreeride215

Location
philly
What do the top end of your plugs look like? Black? inside the plug boots black? A properly installed set of NGK wires and boots fixed this type of problem for me. It would run great in freshwater, but the salt is conductive enough to ground out the spark before it gets to the plug if you have bad wires/boots
 
Skirunner24

Skirunner24

Location
WI
phreeride215 said:
What do the top end of your plugs look like? Black? inside the plug boots black? A properly installed set of NGK wires and boots fixed this type of problem for me. It would run great in freshwater, but the salt is conductive enough to ground out the spark before it gets to the plug if you have bad wires/boots
Click to expand...

Top of the plugs are clean. The whole setup from JSS replaces stock boots with MSD boots. I was also running dielectric grease in the boots.
 
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