rotax senior max evo
(2017 OR OLDER)
NOTE: IF YOU ARE ON AN UPDATED 2018 CYLINDER, PLEASE GO TO THIS PAGE
MAIN JET (ON VP MS93 RACE FUEL): 122 (125 IF AIR TEMP > 85 F / 29.5 C)
MAIN JET ON (93 PUMP FUEL W/ETHANOL): 125 (128 IF AIR TEMP >85 F / 29.5C)
FUEL / OIL RATIO: 44:1 (2.9 OZ / GALLON) OR (22.7 ML / L)
PIN HEIGHT: PIN 4
FLOAT HEIGHT: NEUTRAL TO SLIGHTLY RICH (MIDPOINT OR JUST BELOW MIDPOINT ON ROTAX FLOAT TOOL)
AIR SCREW: 3 FULL TURNS OUT
IDLE SCREW: 4 FULL TURNS OUT (IDLE AROUND 2,500 RPM WHEN ENGINE IS COLD, SHOULD NOT REALLY IDLE WHEN HOT)
OPTIMAL WATER TEMP: 130 F / 54.5 C
SPARK PLUG: DENSO IW27 OR IW29 (IF PERMITTED) OR ROTAX GR9DI**
SPARK PLUG GAP: .7 MM
**NOTE ON PLUGS: Colder plugs (31/34) always look slightly better on the dyno, but they don't make a difference on track. Trust us on this. We have been tuning Rotax motors very successfully for a long time, and this has always been the case. Cold plugs tend to foul on the grid and they don't last nearly as long as 27s or 29s. If you insist on using a 31 or 34 plug, replace it after every competitive session.