New Engine Break-In:
1. A brand new HoBao Racing engine is extremely tight due to high compression. This is normal for a new ABC
piston/sleeve engine. The piston and sleeve are matched for fit and the top of the sleeve is tapered for a tight
compression fit. Your engine is pre-set out of box. You will not need to adjust anything during break in.
If you have adjusted the needles prematurely, please refer to the engine setting above for details.
(Do NOT over rev the engine without breaking it in first.)
2. First, please make sure the carburetor is closed to only 1mm opening. To start the engine, prime fuel by placing
finger over exhaust pipe outlet and pulling the starter several times. This will push fuel to the carburetor.
Then, place glow starter on the glow plug (located in the center of the cooling head), pull the starter handle with
short quick pulls. Engine should start immediately. If not, check fuel line for fuel movement. Do not over prime your
engine as it will cause engine flooding. Only prime the engine until fuel just enters the carburetor.
3. Once the engine starts, heat cycle the engine during break-in procedure. Let the engine idle without the car
moving for 3 full tanks of fuel. Allow the engine to cool down for 5 minutes in-between each tank.
If the engine’s RPM is too high or stalling out, please refer to the engine setting above and confirm the needles
have been set correctly. Engine temperature should be in-between 100-150F degrees (37-65 degree Celsius).
4. After completing the first 3 tanks, you can now adjust the top end needle IN 1/4 turn to improve performance.
Continue to let engine idle or drive around slowly without over revving the engine for 2 additional tanks of fuel.
Allow the engine to cool down for 5 minutes in-between each tank.
5. Break-in procedure is now completed. You can now begin to adjust it for maximum performance.
The first thing you should check is to make sure the carburetor is fully opened when you full throttle.
Keep adjusting needle until engine is running at a good speed without being too hot. Remember to always check
engine temperature. It should NEVER exceed 250F degrees (120 degree Celsius). The optimum temperature for
best engine life is 180-220F degrees (82-104 degree Celsius).
Idle / Stop Screws - Used for
adjusting Idle: Set for 1/16th
inch/1mm gap to start new
engines. You can open more
for higher idle.
Top End Needle (High End) -
Determines maximum RPM and
power. Turning IN is Lean and
OUT is Rich
Bottom End Needle (Low Speed) - This needle provides throttle response.
Do not adjust this needle until the Top end Needle is set for power and top speed.
Turning IN is Lean and OUT is Rich
Mid Range needle - The needle on
the side of the carb.
DO NOT TOUCH.
TEL : +886-2-2996-2229
FAX : +886-2-2996-8213
www.hobao.com.tw
Engine Needle Settings:
Top End (High Speed)
Bottom End (Low Speed)
Mid Range
Idle Screw
Factory Default After Break-in
1mm (1/16 inch) 1mm (1/16 inch)
4 turns out
Flush
Do not Touch
3 to 3 ½ turns out
Flush with ball collar
Do not Touch
Thank you for purchasing HoBao Racing products. We appreciate your choice.
Fuel Recommendations:
We recommend using 20% Hobby Grade Nitro Fuel for 1/10th scale (.12-.18 Engine) and 30% for 1/8th scale (.21 and up).
Other types of break-in additives are NOT required.
