I have read thru most of this discusion and there is an old school way to adjust the LSN needle and I also discuss some glow plugs.
http://www.xenonproject.com/tuning-y...gine-a-10.html
The old school way of adusting an LSN is called a pinch test. The engine should only run for a few seconds after pinching the fuel line.
[*]Step 2. Low-Speed Fuel Mixture Adjustment
- The low speed mixture adjustment is performed only after the high speed needle has been correctly adjusted. The easiest way to adjust the low speed mixture is by doing the "pinch" test. The valve is located where the throttle arm pivots.
“Pinch” Test
Having set the high speed needle correctly, take the RC vehicle and pinch the fuel line going into the carburetor. The engine should run for about 2-3 seconds, speed up, and die.
If the engine runs longer than 3 seconds, give the low speed needle a 1/16 turn clockwise. Run the vehicle again and retest. Repeat as necessary.
If the test results in the engine dying immediately, without speeding up, richen the low speed needle by giving it 1/8 turn counter clockwise. Run the vehicle again and retest. Repeat as necessary.
Once the low speed needle is correctly adjusted, the engine throttle should respond very quickly. It is now time to adjust the idle speed.
Now we can get into Glow plugs while there is no perfect solution for these in the winter time HOT plugs will keep an engine running longer because in the cold air temps you require richer fuel mixtures, In the summer time Meduim Heat Glow plugs will last longer in most fuels between 10 to 30 % nitro. Why because the Filiment is thicker. For racing engines some suggest cold plugs when running 30% or over nitro content. Problem with Cold plugs they will flame out if the idle screw is not set right on the edge of clutch engagement..
This chart indicates the direction in which you should adjust the fuel mixture when faced with changing conditions. It assumes the engine is currently well tuned. You could face any combination of conditions listed in this chart. Knowing how to adjust the fuel mixture is a crucial part of operating and maintaining your RC vehicle. | Higher Air Pressure | Lean |  | | Lower Air Pressure | Rich |  | | Higher Humidity | Lean | | | Lower Humidity | Rich | | | Higher Barometric Pressure | Rich | | | Lower Barometric Pressure | Lean | | | Higher Altitude | Lean | | | Lower Altitude | Rich | | | Higher Nitro Content | Rich | | | Lower Nitro Content | Lean | | | Higher Oil Content | Lean | | | Lower Oil Content | Rich | | | Hotter Glow Plug | Rich | | | Cooler Glow Plug | Lean | | | |
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