engine slow at reaching max. RPM

[DigitalBurn]

Hi.

I have a Magnum 45 engine that seems to be sluggish at reaching maximum RPM.

I WAS having trouble with it leaning out and stalling after takeoff, and dropping RPM's when the glowplug clip is removed, but that seems to be all okay now. Different glowplug, couple clicks richer. Just me being a novice, mostly.

Now, when I open it up full throttle the RPM's pick up really well, until the RPMs reach about where they would be if I had the throttle open only 3/4. Then, from there, it takes a good 5-10 seconds to reach maximum RPM. Is that normal?

I'm using a O.S. no.8, instead of the stock recommended R/C Long. It seemed to be burning to cool with the Fox R/C long.

And a 11x6 prop. Manual recommends 11x5, or 11x6.

I also leaned the idle mixture because it was hesitating when I opened it up.

Any suggestions or comments would be greatly appreciated.

[Dave Robelen]

Hi Digitalburn,
First a question. Do you see a bunch of excess exhaust during this sluggish acceleration? That would indicate that either the idle or midrange setting is a bit too rich. When the idle is set correctly, you should notice the engine dying lean slowly when you raise the nose about 30 deg. while at idle. If it continues to idle very nose high, I bet the idle mixture is a bit too rich and fuel is accumalating in the crankcase which gets pulled up during accellaration. I would check the instructions for setting the idle, and also the midrange on the carburetor if that is adjustable.
Regards, Dave

[DigitalBurn]

Hmmm . . .yeah, it sounds like it's loading up with fuel and it takes the engine a few seconds to "catch up" with the fuel load.

I have main mixture control, and an idle mixture control. I have the main as lean as it can be without having adverse affects. I suppose I could lean the idle mixture out more.

I do notice a trail of smoke as I throttle up and make a fast climb. It actually looks really cool, and is enticing me to get a smoke system, but I'd rather have the engine run well, first.

Thanks for the advice.