STS engine is designed and manufactured for high level of competition performance. To get the best performance and reliability out of this engine, you must read these instructions carefully. Please treat your STS engine with care to ensure the engine carries long lasting high- performance working time. Several essential factors must be considered to achieve the optimal performance of this engine:
This engine should ONLY be used with fuel particular blended for R/C model car. Never run this motor with gasoline! The choice of fuel is very important, it should contain a minimum of 12% castor and/or synthetic oil by volume. Regarding the percentage of nitro: more nitro content (higher %) will provide more explosive power from your engine, but it will also shorten the engine's life. For average use, we recommend 15~30% nitro fuels.


Check your glow-plug regularly. When the glow-wire becomes dull or mat and the engine stalls without reason, change the glow plug. A new glow-plug will keep the engine idle stable and optimize its performance. An old glow- plug is prone to glow-wire broken, melted or missing. If you keep on using an old grow-plug, you may damage your engine. Please avoid this situation and check the plug regularly.
NEVER run without an air-filter, you will ruin your engine. A good air-filter is very important to extend the life of your engine. When you use a foam air-filter, don't forget to impregnate the foam with air-filter oil before use. You must change your air-filter regularly. Washed and re-used foam filters may shorten an engine's life due to the deterioration of the foam element after extensive use and washing.
NEVER run without a pipe, it will cause the engine to over-heat and will damage your engine. A correctly installed tuned pipe will let the 2-stroke engine run at peak performance. We recommend that you choose STS tuned pipes since the STS tuned pipes are developed with our engines.
There are 3 needles on the slide carburetor can be adjusted. When you are adjusting any one of the needles, each adjustment should be of the same magnitude and always kept to minimum (use small increments). Check the engine temperature regularly and keep it under 120 °C (248 °F). **
High Speed Needle
Adjusts the main flow rate of the fuel (when the throttle is open significantly). Less fuel (leaner) will make higher rpm but will also generate a higher temperature. Tune the main needle to adjust the engine rpm at high-speed and open-throttle.


Be careful of the engine operating temperature and check it regularly when adjusting this needle. Lean setting = clockwise turn, more rpm (power) at full throttle, more heat. Rich setting = counter-clockwise turn, less full throttle rpm, less heat, more lubrication. No smoke from the exhaust and high temperatures are indicators that the setting is too lean and possibly harmful.
Low Speed Needle
Adjust the low-speed fuel flow rate. In general, less low-speed fuel flow provides your car with more fast response when you first hit the throttle. But if the LSN is too lean the engine will be overheat easily. Tune this needle to adjust the low-range reaction.
Idle/Air -Screw
Adjusts the airflow when the throttle valve is at idle position. Less airflow will make the less rpm. Tune the idle/air-screw to adjust the idle speed. Screw in (clockwise) for a faster idle. Screw out for a slower idle.
Be careful with the engine operating temperature. You have to measure the engine temperature regularly. Over-heat the engine will cause permanent damage to the internal parts of the engine. If you can't measure temp. make sure smoke is always being generated out from the tuned pipe. Engine operating temperature is depended on air temperature. It's not always the same. There is the suggestion of Engine operating temperature;
Air temp. 5°C(41°F) 5-15 °C(41-59°F) 15-25°C(59-77°F) 25-35 °C(77-95°F) 35+ °C(95+°F)
Engine temp. 60 °C(140°F) 80 °C(176°F) 100 °C(212°F) 120 °C(248°F) 120+ °C(248+°F)
Grow Plug Super Hot Hot Middle Cold
If your engine is brand new, the piston and liner is very tight. It is normal hard to start it up. You can use hairdryer to pre heat the engine. Or loose the glow plug half turn then try to start the engine. Once the engine started remember screwing the plug up.


1.Install a new glow-plug. Hotter rated plugs will be better for the
rich settings used during break-in.
Turbo head button needs conical type glow-plug.Choice hot glow-plug for break-in then you won't have problem.Please increase 0.1mm of head shim.
2. Use high castor oil(12% or above) and low nitro rated glow fuel, 5%~15% nitro is best. Make sure the fuel is fresh and high quality special blending for R/C model car.
3. Start by counter-clockwise turning the high speed needle 1 full turn. Open the carburetor to full throttle and hold it there. Turn counter-clockwise the high speed needle until the engine flames out. From here, turn clockwise the high speed needle ¼ turn and restart the engine again running it at full throttle. Run the engine full throttle for 1 tank and shut the engine down.Allow the engine to cool for 15-30 minutes. Before second tank, leaning HSN 1/4 turn and start using the throttle by doing 2-3 times bursts of full throttle. When the temperature is up to 176F~194F shutting down the engine. Let the piston on the end position and assembling the heat sink again(just this time) then let the engine cool down. Repeat this process with two tanks. Then you can go to run-in. Be care of the temperature is under 248F.Allow the engine to cool for 15-30 minutes and then you are ready to hit the race track. Drive two tanks rich around the track slowly closing the high speed needle sneaking up on that perfect mixture.
4. Next several tanks of fuel: run the car on the track at low speed (50% to 80% throttle). Avoid using a constant throttle position; keep blipping the throttle to vary the rpm, slow-fast-slow-fast etc. Check the temperature regularly and keep it between 80 °C (176 °F) and 100°C (212 °F)**, if you can not measure temps make sure the engine is running at heavy smoke from the tuned pipe.

5. When your engine is still being run-in, higher running temperature is expected. As time goes on, running temperature will be lowered. At this point you may lean the engine by turning the main needle clockwise incrementally and keep the engine running temperature at or below 100°C (212 °F) .

6. After about 1~2 liter fuel through it, take out the glow plug and turn the flywheel by hand, let the piston pass the top dead center in the sleeve. When you don't have any significant friction or just a little snug, you can start leaning the main needle incrementally in small steps, and keep it around 100~120 °C (212~248 °F)** .

7.We suggest you to check the main bearing and connecting rod's condition after break-in process. The best is replace a new connecting rod and all new bearings then just start to lean it. If you do this your engine will be long life.



If your engine is equipped with a pull-start system, there is something you must know before you start it. Remove the glow plug then draw the line out slowly till the end. Remember the total length of the line and never over draw out the line. The pull-start system is very small so it is impossible to have a long line in it. Never treat it as your lawnmower!

Never draw out the line more than 30cm. When you start your engine your hand should move between 10cm ~ 30cm speedy. Block the tail pipe then pull few times, the fuel should be pumped into the carburetor. Then ignite the glow plug and start the engine. It should be started after some pulls. If you can't start your engine under some pulls, you should check your carburetor setting or the plug's ignition first. Also make sure the tuned pipe or manifold won't touch the line when you mounting the engine.

It is recommended the use of rcengine after run oil to keep internal moving parts of the engine lubricated. After-run oil helps for an easy start next time, protects your ball bearings and extends your engines life. After run oil can be applied via the throttle body or glow-plug hole. Ensure the areas are absolutely clean before you remove engine components, enter of debris into the engine is harmful.
You must treat your engine with care. This high performance STS Racing engine may work up close to 40,000 rpm. Any failure at such a high rpm can cause damage and exemplifies why you need to regularly maintain your STS racing engine. Please understand that all moving parts inside the engine are subject to wear, and that if a piston/liner has worn out then likely the end/con-rod has also worn. When these parts are eventually in need of replacement, they are readily available and easy to install. If an engine has been broken, check to see if all of the other moving parts are still in good shape. If you only replace one part and leave other worn parts in place, it is possible that you will soon have another failure.

* Clean the outside of the engine before you open it. Any dust or dirt that enters the engine will cause considerable damage.

* Check the end of the con-rod frequently. If you want to replace the con-rod, be sure the big end of the crankshaft pin is not worn out, if not, replace the crankshaft as well.

* If the engine does not sound normal and runs loudly, it may be caused by worn bearings. Replacing the bearings requires the use of a special-tool; ask for service from your local hobby shop.

* When you start the process of installing/building your STS engine, each part should be thoroughly clean prior to installation. Be careful that each part is in its correct orientation, especially the piston/sleeve/con-rod. The skirted side of the piston should be facing to the front (carburetor side). The exhaust port (maxi-port) of the sleeve should be facing to the rear. The lubricative ditch of con-rod should be facing to the front of the engine (carburetor side).

* Before you install the head button, do not forget to install the proper number of head shims. We suggest that you use at least 0.3 mm head shims. You may need to adjust the thickness of head shim for best performance. These are our guidelines.

21/28/30 engines
FUEL Total thickness of head shim
- Under 20% Nitro 0.3 mm
- 25% Nitro 0.4 mm ( +/- 0.1 mm)
- 30% Nitro 0.5 mm ( +/- 0.1 mm)

 12 engines
FUEL Total thickness of head shim
- Under 20% Nitro 0.3 mm
- 25% Nitro 0.4 mm ( +/- 0.1 mm)
- 30% Nitro 0.5 mm ( +/- 0.1 mm)

* Use a high quality hex wrench to install the screws. When you start to feel resistance, stop turning the screw. Repeat this for each screw. Use the "Star" technique to finish tightening the screws of the cooling head. Do not over-tighten the screws.

**All suggested engine temperature of this manual is based on 25 °C (77°F)out door temperature.
Any other question please mail us.
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