YS 91 SR

The YS .91 SR is the latest big block engine from YS. This engine is a very user friendly with respect to tuning.  Please follow the factory recommended settings for break in procedure.

Listed below are the settings I have found to work well using the following equipment. Enya 3 plug, Hatori SB-19, cool power 30% fuel also a futaba gv-1 governor. After break in, this should only take a few gallon’s, you can start leaning the engine down a little.

• Low end – 1.25/1.00 from fully closed
• Midrange – 1.75/1.5 from fully closed
• High end – 1.0/0.75 from fully closed

Remember these settings are approximate settings as temperatures change so will your engine settings. Remember that hot you need to lean, cold you need to richen.

Gear ratio testing I have found through extensive testing, that 8.0 to 8.2 will deliver the ultimate performance for 3D flight. I run no more than 1850 on head speed and this seems to work very well.