Hi Kafin,
I run an LA-46 on a tongue muffler (all holes open) in my Vector 40 with 5% nitro, 20% oil mix and a 12.5 X 4 APC prop. I have tried a couple other fuels (5% nitro/18% oil, 10% nitro/18% oil, and 10% nitro/20% oil) and had either power issues or overheating. I've found that with the heat and extreme humidity in our climates that even seemingly small fuel changes can throw the motor run off.

Before takeoff I set the needle to where the motor is in 2 cycle and just cracking into a 4 cycle every couple seconds. The lap time is around 5.1-5.2.

Hi Jake,

Thanks for sharing your thoughts.
Why did you decide to use 5% nitro fuel instead of using the 10%? I thought with the heat we have here it will be better to use 10% nitro.
I’ve been using 5% nitro for the past year but I was thinking to switch to 10% nitro.

Kafin, What kind of fuel are you running? How much castor oil is in your fuel? Some off the shelf fuels only contain 16%. Maybe that's the cause of your black exhaust residue.

It’s a local brand fuel with 5% nitro 20% oil (which I suspect this is full synthetic oil).
I might have to try switching to VP Powermaster 10% Nitro 22 oil (50:50)

Just like the OS owner's manual says, I find peak rpm on the ground (i.e.: if I go any leaner the speed starts to fall off). Then, just as the owner's manual says, I open (richen) maybe 30 deg or so just when I notice the rpm to just start to decrease a little. OS calls this the 'optimum' engine speed. Then I fly the model.

Thanks for mentioning this, Colin.
I was trapped to match the suggested ground RPM number for that specific prop on LA46 without finding what will work on my flying location.

this is where I get castor
https://www.bulkapothecary.com/raw-ingredients/bulk-natural-oils/castor-oil/
runs fine
Fred Q

Thats a good price.  Just ordered four gallons.  Shipping cost is the same as one gallon.

Dave

this is where I get castor
https://www.bulkapothecary.com/raw-ingredients/bulk-natural-oils/castor-oil/
runs fine
Fred Q