DoubleDD

ST 2300 surgeing. when tuning in 2300 with 5% nitro at full throttle the engine surges. Can you tell me what is happening to cause this surging? Thanks

Bax

My Feedback: (11)

Surging is caused by incorrect carb settings. Likely, it's too rich and not yet fully broken-in. Please see our guide at the top of this forum on getting your engine adjusted.

For breakin, run it very rich and gradually lean it. The engine is ready to fly when it can sustain running at full throttle when leaned to just rich of peak RPM. Breakin isn't complete at that point, but will happen over the next gallon or two.

DoubleDD

this engine has about 3 and half gallons through it already. makes no difference leaning or richening. does same thing in flight
. Also wants to die out if in vertical and idle down and then give throttle again

Bax

My Feedback: (11)

If an engine quits running when the model is in a vertical attitude, it means you have a fuel draw problem.  The engine just can't pull the fuel "uphill" fast enough to hold a good mixture.  The engine goes lean and quits.  You'll either need to use larger fuel tubing throughout the fuel system to eliminate fuel-line drag, or use another method to deliver the fuel to the carburetor under higher pressure.

If the engine quits at reduced throttle settings, regardless of attitude, you have a mixture-setting problem.

You  may also want to check your fuel.  If it's old, it may have absorbed moisture, which will affect how well the engine runs.

To check engine problems, mount the engine on a good test fixture with a good fuel system.  If the engine will run well "all day", at all throttle settings, then you do not have an engine problem.  The problem will lie in the airframe/engine/fuel system combination, and you'll have to debug that.