This app helps you jet your 2-stroke Yamaha YZ (PW 50, PW 80, YZ 65, YZ 80, YZ 85, YZ 85 LW, YZ 125, YZ 125 X, YZ 250, YZ 250 X) and get the most out of it. From the temperature, altitude, humidity, atmospheric pressure and the oil-to-fuel ratio it works out the jetting recommended for your exact model.
To get the weather values the app can use the location service and the data connection: it takes your position and altitude, queries the nearest public weather station and brings back its readings. It also works with no GPS and no data, entering the weather by hand.
The app has 4 tabs:
- Results: the recommended main jet, needle type and clip position, pilot jet and air screw turns for the conditions and the bike you set, plus air density and density altitude. It has fine tuning per circuit —high, mid and low— to match the character of one particular engine.
- Conditions: temperature, altitude, pressure and humidity. Type them in, or pull them from the nearest weather station with one tap, without leaving the screen.
- Engine: year, region, model and oil mix ratio. The carburettor is not a choice: the year, region and model determine it. Underneath sits the mix calculator: it converts between petrol, oil and ratio both ways —in litres, millilitres, US and imperial gallons and ounces— and leaves the ratio set here with one tap.
- Logbook: saves each ride with the bike, the weather and what the app recommended, so you can note afterwards what you actually fitted and how it went, rated per circuit. Export it to CSV or share a copy to move it to another phone; importing never deletes anything.
Units: metres and feet for altitude, ºC and ºF for temperature, mb, hPa, mmHg and inHg for pressure, and kg/m³, lb/ft³ and lb/gal for air density.
No ads, no tracking and no account.
Yamaha YZ models that are included:
- PW50 from 1995 to 2027.
- PW80 from 1995 to 2024.
- YZ65 from 2018 to 2027.
- YZ80 from 1995 to 2001.
- YZ85 from 2002 to 2027.
- YZ85LW from 2022 to 2027.
- YZ125 from 1995 to 2027.
- YZ125X from 2016 to 2027.
- YZ250 from 1995 to 2027.
- YZ250X from 2016 to 2027.
