The ski ran fine, you changed the oil, and now it tops out about 500 rpm lower than before. When you open the air filter housing there is oil in it. This is a pattern owners of the TR-1 skis describe over and over. That means the 1049 cc three-cylinder engine in the VX from 2015 or 2016, the EX from 2017, the four-stroke SuperJet and the JetBlaster, and the usual story is an oil level that ended up too high.
What owners report
Overfilling costs rpm, and the figure that comes up is around 500. It also pushes oil into the intake tract, which is why the air filter gets wet. The electronics don't see the oil level, so a fault code isn't something to count on. The engine runs, it just doesn't rev out.
The older MR-1 skis have a similar report. One VX1100 owner described the rpm hanging at around 5000 on the water but reaching 8000 when revved on land, and the cause turned out to be an air filter box soaked in oil after an oil change with too much in it. That is a single account, but it fits the same mechanism.
How to check the level properly
Owners say the level should be checked only after about six minutes of running time and with the ski sitting on level ground. Checking right after filling, or on a tilted trailer, gives a reading that depends on how the ski sits. The engine must never run on land without water supply, so get that running time on the water or with a proper water supply, then check the level with the ski sitting flat.
If the level is above the upper mark, take the extra out. The usual way is an oil extractor, and then you check again. If the air filter is soaked, it needs cleaning or replacing before you judge how the ski runs, because a wet filter alone will hold back the engine.
What the scan can and can't tell you
A diagnostic app doesn't measure oil level, oil in the filter or oil in the intake, so it can't confirm this problem. What it can do is rule other things out. With the M-JET Diagnostic on a VX, EX, SuperJet or JetBlaster you can check that the fault memory is empty, that the throttle valve opens as far as the lever commands, and that intake pressure responds. If the live values are normal and the ski is still 500 rpm short, a mechanical cause like oil in the intake moves to the top of the list.
On the SuperJet, check one more thing. The learning mode limits power and can look like a defect, so make sure it is off before blaming the oil.
After the oil change
Once the level is right, reset the oil change interval so the reminder starts again. The app does this on models that offer the function, see oil change and service reset. Then take a short test ride and compare the top rpm with what the ski did before. If the rpm is back and the filter stays dry, you are done. If oil returns to the air filter after a further ride, the level was only part of the story and the engine needs a proper look from a mechanic.
