Sorry for the long post, but here it goes.

Az

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Carburetor Adjustments and Notes:

High Speed Needle Adjustments:

All adjustments should be made by ⅛ turns or 30° and then a few high-speed runs should be made to see the effect of the changes. The engine should NOT be leaned any more if any of the following appear:

• There in no longer any performance improvements
• The engine begins to cut out at high speed
• There is a sudden loss of power during acceleration
• The engine begins to overheat showing stream or smoke coming from the engine or, no smoke from the exhaust or, hesitation or stalling during acceleration or, popping or clattering sound when decelerating (detonation) or, fluctuating at idle speed.

If any of the above appears then you should STOP and let the engine running but richen it by Ľ of a turn and let it idle for about 10 minutes.

Mid Range Needle Adjustments:

Mid range needle controls the flow of fuel between the idle speed and full throttle. This needle should be kept at factory settings unless you have mastered the art of adjusting the carburetor.

Low Speed Needle Adjustments:

After you finish setting up the High Speed Needle, set up the Low Speed Needle but make sure that the High Speed Needle is set correctly. One other notice, all adjustments to the Low Speed Needle should be made while the carburetor is slightly opened so you don’t push out the Mid Range Needle by mistake while adjusting.

To ensure that the Low Speed Needle is setup correctly, accelerate to full throttle from a full stop after you let it idle for about 5 seconds, if the engine emits heavy amount of smoke and hesitates before accelerating or shuts down, then you should lean it, if the engine sputters (to make a popping, spitting sound) and shuts down before accelerating with little or no smoke, then you should richen it.

A perfectly tuned Low Speed Needle will allow the engine to run for about 2 to 3 seconds then dies when the fuel line is punched. But make sure that all adjustments to the Low Speed Needle is don after the engine is at its operating temperature range.

Idle Screw Adjustments:

You must set the idle screw at a speed that when you lift the car the tires do not move and you should be able to roll them back, and when you hit full breaks the engine should not shut down. The idle of the engine must be stable.

Peak efficiency:

The primary concern should be the amount of smoke that is seen when the car is exiting a turn. There should be a good amount of smoke with every acceleration.

Second, the idle of the engine must be stable.

Third, the glow plug wire (when checked after the run) should be shiny and unbroken.

Fourth, the performance of the engine should be good throughout the power band.

Also listen to the engine as it goes around the track and determine if it is running rich (a deeper exhaust note than normal at low RPM), running lean (at full RPM, a cutting out sound) or normal.

How to know that the engine is too lean:
• The engine begins to cut out at high speed with little or no blue smoke
• There is a sudden loss of power during acceleration
• The engine begins to overheat showing stream or smoke coming from the engine or, no smoke from the exhaust or, hesitation or stalling during acceleration or, popping or clattering sound when decelerating (detonation) or, fluctuating at idle speed.
• When the engine shuts down when the tank is half full


How to know that the engine is rich:
• Sluggish acceleration with blue smoke coming from the exhaust
• Not shifting in 2nd gear if equipped
• There is unburned fuel spraying from the exhaust tip
• Leaning the High Speed Needle increase performance
• When the engine die when given some throttle


Glow Plug:
If the engine die when the glow plug igniter is removed, that means that your glow plug is bad or damaged. It must be replaced. You can read the glow plug by following this chart:

• Engine: Running rich: (Wire : Wet) (Bottom : Wet) (Color : Shiny) (Shape : Normal)
• Engine: Running almost at full efficiency: (Wire : Mostly dry) (Bottom : Mostly dry) (Color : Slightly gray) (Shape : Normal)
• Engine: Running at peak efficiency: (Wire : Dry) (Bottom : Dry) (Color : Gray) (Shape : Normal)
• Engine: Too lean: (Wire : Dry) (Bottom : Dry) (Color : Dark Gray) (Shape : Deformed)
• Engine: Far too lean: (Wire : Dry) (Bottom : Dry) (Color : Black) (Shape : Deformed)

After Break-In Tuning:
You must adjust the carburetor if the weather changes. Use the following guide.

• Air temperature: (Higher : Lean) (Lower : Richen)
• Humidity: (Higher : Lean) (Lower : Richen)
• Altitude: (Higher : Lean) (Lower : Richen)
• Oil Content: (Higher : Lean) (Lower : Richen)
• Barometric pressure: (Higher : Richen) (Lower : Lean)
• Nitro Content: (Higher : Richen) (Lower : Lean)
• Glow Plug: (Higher : Rich Hotter Glow Plug) (Lower : Lean Colder Glow Plug)

After run oil:
You can use a branded “After Run Oil” or automatic transmission oil as a substitute. Some say not to use “WD-40” because it was not designed for use inside 2-stroke engines.

Fuel types:
You should only use fuel designed for R/C cars, and check on the oil requirements by the manufacturer of the engine (OS Max 18% oil content is recommended, HPI 14% oil content is adequate).

Operating temperature:
Generally between 90 Celsius and 110 Celsius is good

Adjust a 2 Speed shifting point:
To make the transmission shift earlier turn the adjustment screw “Counter clockwise”. To make the transmission shift later turn the adjustment screw “Clockwise”.

Tweak or droop screws:
Tweak is a condition at the front or rear of the car where one tire has more load on it than other. If the right rear tire has more weight on it than the left rear tire the car is said to be tweaked. This can make the car behave unpredictably. To check tweak, set the car on a flat level surface, and then using a hobby knife, lift one end of the car at the center point. Watch closely, which tire lifts off first. You can adjust the tweak by shortening the droop screws or the ball end of the shocks shafts.


Flywheel:
The flywheel help balance the engine front with the back, were it offsets the weight of the crankshaft. It is very important to check the flywheel from time to time that it is setting tightly of the pilot shaft with no clanking sound. If you hear a clanking noise coming from your engine, it might be a problem with the flywheel and not a problem with the engine itself. To fix this retighten the pilot shaft. Inspect the inside of the flywheel (it should fit tightly on the pilot shaft). If there is little wear, apply thread-locking compound to the crankshaft and reassemble the pilot shaft/clutch bell assembly.

There are many methods to removing an engine flywheel. The easiest method that will not damage the engine's piston is the "hydro lock" or "hydraulic" method. With the engine out off the chassis, glow plug install and the exhaust header removed, turn the engine upside-down. Use a non-silicone after run oil to fill the cylinder. Turn the flywheel until the piston compresses the after run oil against the top of the cylinder. Now you can turn the engine upright and use a 8mm wrench to remove the pilot shaft. Remember when attaching the pilot shaft on the crankshaft to use thread-locking compound

Clutch:
The main reason for the clutch shoes melting to the inside of the clutch bell is the engine's idle speed was too high. If you have to use your foot or a curb to stop the car when it's supposed to idle, your idle speed is too high and the clutch shoes will melt eventually. When you have the brakes applied, the clutch shoes are still expanding and contacting the inside of the clutch bell. This contact (friction) creates heat, and although the clutch shoes are made from a heat-resistant plastic, the clutch shoes eventually melt into one solid mass and prevent the springs from bringing the clutch shoes into their normal position.

You have a bad clutch if:
• The wheels don't turn forward, even if you give it throttle (Also check all drive-train parts)
• The tires start spinning when the engine starts (Make sure the idle speed is not too high)
• The clutch bell cannot be moved by your fingertip.

Gear mesh:
The easiest way to learn that you have the correct gear mesh is to use a piece of paper and fit it between the spur gear (More teeth = More torque, Less teeth = More speed) and the pinion gear on the clutch bell (Less teeth = More torque, More teeth = More speed) as you tighten the motor mount screws.

After the motor is completely tightened, the piece of paper should be impossible to remove except by turning the spur gear to rotate the paper out of place. With the paper gone, turn the spur gear with a finger and feel the amount of movement or "play" there is between the spur gear and pinion gear. There should be very little play, but you should feel a little bit. This is the correct gear mesh. With practice, you will no longer strip any spur gears. Please note that the spur gear side facing the front of the car should be flush with the pinion gear at a 90° angle.