Two used Yamaha skis can show the same number on the display and have lived very different lives. One idled around a lake and the other spent a good part of its life near full throttle. The display counter doesn't tell you which is which, and owners say it isn't always reliable in the first place.
What the display shows and what it doesn't
The hour meter in the display is a single number. Forum reports describe it as not always trustworthy, without a consistent pattern behind that, so I would treat it as an indication and nothing more. If a seller points to it as proof of a gentle life, that is a claim to check, not a fact.
What the control unit stores
The control unit keeps its own record. It stores total engine hours and also the hours the engine has spent in each rpm range. On most models that is six bands up to 12000 rpm. The GP1300R, an older ski that doesn't rev that high, has four bands up to 8000 rpm. The M-JET Diagnostic reads these values over Bluetooth, along with model, engine serial number, SCC code, ECM part number and software version. The details are on the page for reading operating hours.
What matters is the distribution. A ski whose hours sit mostly in the lower bands was cruised. One with a large share in the top bands was run hard, and a ski with many hours up there deserves a closer look at everything mechanical, especially on the supercharged models where heat and load are higher. That is an inference and not a measurement of damage, but it is one a display counter can never give you.
How to use it when buying
Read the stored total first and compare it with the display. If they match roughly, good. If the display reads far lower than the control unit, ask the seller about it. A difference doesn't prove anything on its own, and one number is no reason to accuse anybody.
Then look at the bands. A ski that was rented out or raced may show it as hours in the high ranges. The hours are one item in a full pre-purchase check, along with fault memory, live values and the component tests, which checking a used WaveRunner goes through.
What the numbers can't say
- Whether the ski was serviced on time. Hours don't record oil changes.
- The condition of the impeller, wear ring or timing chain.
- Whether a hard hour was spent in clean water or in sand.
Comparing like with like
The band layout differs between models, so compare a ski with others of its own type. Hours in the top band of a GP1300R, which only goes up to 8000 rpm, mean something different from hours in the top band of a ski with six bands up to 12000 rpm. Two FX SVHOs, or two VX Cruisers, can be set against each other directly. A GP1300R against a VXR cannot.
The stored total is also worth keeping next to the engine serial number, because the hours belong to the engine and the serial number says which engine you were looking at when you read them.
For your own ski
Reading the bands once a season gives you a trend line. If the share in the top bands grows quickly, the ski is being used harder than you thought, and that is useful to know when the maintenance schedule is set. It is also a clean reference to hand to the next buyer, with the vehicle data next to it so the numbers can be tied to the right engine.
