To add a bit on Don's comments, rich running at idle, mid range and WOT is a must if you want bearing life and consistent engine running over the long run. That is true for any engine not just the OS. That requires proper pipe set-up and good fuel with 15-20% nitro and plenty of oil, and not going too far on the idle mix adjuster. A hot plug such as the OSF type, makes for a fine combination
MattK
ORIGINAL: woodie
ORIGINAL: Aresti-RCU
Pardon my ignorance, but this is my first experience with the OS140RX (coming from four stroke to a Webra 160 to the RX now...) The manual doesn't say how to adjust the low end needle. Which side is lean and which is rich (CW or CCW)?
CW is leaner. It is fairly sensitive, small adjustments, a little at a time, the whole idle adjustment only turns about 1/4 turn stop to stop. Most of my engines seem to end up with the idle adjustment just CW of 'centered'. You want to be able to run the idle as rich as possible and still get a good transition. The richer the idle, the faster the motor will drop to low idle when throttling down.
Don