First, remove your car's air filter (and rubber breather neck) so that you can see the carburetor slide from above. Then, remove your throttle linkage (snap the ball end off of the stud) from your engine's carburetor slide. Manually open and close it to make sure that it never closes past the 1-2mm that your manual suggests. Turn the idle screw clockwise to increase idle opening, and counter clockwise to decrease idle.
The reason for adjusting the idle position without the linkage attached is sometimes you can accidentially adjust your linkage such that you think the carburetor is closing all the way, but the linkage will allow it to close more when you hit the brakes.
Once your idle is properly adjusted, re-attach the throttle linkage. Make sure your batteries are fully charged. Then turn on the transmitter, followed by the car. Move the throttle back and forth, and make sure that the car does not "glitch" (cause undesired servo operation) when moving the trigger back and forth. Also, ensure that the linkage allows both the slide to fully close when you let off the gas, as well as opening the slide all of the way when you apply full throttle.
While you have the car on your workbench, now would be a good time to mark Bottom Dead Center (BDC) on your flywheel. Simply remove your glow plug, and insert a thin screwdriver down to rest on top of the piston. Spin your car's flywheel until the screwdriver has come to rest at the lowest point. Mark the flywheel with a magic marker (not on the side that the starter box rubs on) so that you can quickly return your car's engine to this position when you turn your car off. By doing this, you make sure your piston is returned to the bottom of the stroke, where the tapered cylinder is at its widest. This will ensure logner engine life.
Now that you have a properly set idle and know about BDC, review the following, as it is a few steps I have come up with, to help people grasp engine tuning easier.
All nitro engines are unique so no two will have the identical tuning . What works for one engine could blow up another. Here are my 7 steps to a tuned engine:
**Note** You need a temp gauge , for the below. I have an OFNA PCR gauge which Nitrohouse has for under 30.00 right now. Take all temperature readings by pointing your guage directly at the glow plug. All temperatures are listed in degrees Fahrenheit.
1.) Reset needles to stock settings, including the idle (you may need to lean slightly over stock settings to keep car running)
2.) Warm car up until chassis gets hot, making sure temps never exceed 250
3.) Lean HSN (high speed needle) to keep temps between 220-250 making sure smoke is visible between low to mid RPMs
4.) Lean LSN (low speed needle) until pinching fuel line near carb causes engine to stall between 3-5 seconds
5.) Check to make sure low end changes haven't made motor exceed 250, if they have richen HSN
6.) Adjust idle as high as you can without engaging the clutch (car should not move).
7.) Re-check above any time outside weather changes significantly, or at the beginning of a day of driving
The above ritual can also be used to break in an engine. Simply keep the temps slightly lower, say 200-220, do not make sudden throttle input changes, keep the engine below 1/2 throttle, and only allow the car to run for 2-3 minutes at a time. Quickly return your engine to BDC, and allow it to cool fully to ambient air temperature. Repeat this ritual until you have done about a half hour worth of 2-3 minute runs (not counting cool down time), and your engine should be ready to go.
