2001-2005 Yamaha WaveRunner GP800R Factory Service Manual, Page 310Get this manual

E 5While lightly squeezing the throttle lever, push the start switch (green button)
WARNING
On this watercraft, the engine is connected directly to the jet pumpStarting the engine immediately generates some thrustApply only enough throttle to keep the engine running6Release the start switch as soon as the engine starts to run
CAUTION:

• ATV
• Jet Ski
• Outboard Motors
• Personal Watercraft
• Snowmobiles
• Stern Drives