For your questions and information about OS engines, we would request you to basically contact distributor in your country or your region listed on International Contacts Listing.
Only when you cannot receive proper answer/information from the distributor, please contact .
We would solicit your understanding to make you wait long time, when questions rush to OS.

6-15, 3-Chome Imagawa Higashisumiyoshi-ku Osaka 546-0003 Japan
TEL(06)6702-0225 FAX(06)6704-2722

Overcoming minor problems

When actually enjoying gas powered R/C cars, you will likely encounter problems for which you cannot determine the cause even if you understand their construction, handling, and maintenance methods. In the event such a problem occurs, use the following troubleshooting chart as a reference for solving your particular problem.

* We plan to add your questions and our answers to these pages.

The engine does not start.

Check 1   Is there fuel in the tank?   The engine will not start without fuel. First check the fuel tank. Of course, be sure to use glow fuel made exclusively for R/C engines. If you are not sure of the type, ask your dealer for fuel for gas powered R/C cars.

Check 2   Is the fuel pipe detached (or leaking?)   Be sure to securely attach the fuel tube to the fuel inlet nipple and to the fuel tank. Of course, if a filter is installed, it is necessary to check before and after the filter. You should also check that the flow of fuel is not blocked by twisting of the tube.

Check 3   Does the fuel reach the carburetor?   Press the choke button on the fuel tank and check that the fuel reaches the carburetor. When cranking the engine while blocking the muffler and carburetor with your finger, check to be sure the throttle is open.

Check 4   Is the needle valve open the correct amount? Or is the needle valve closed completely?  

From its completely closed position, open the needle valve by turning it 3-4 times in the counterclockwise direction. Then, after sending fuel to the carburetor, the engine can be started.

Check 5   Is dirt clogging the fuel line?   Is fueling performed carefully from the fuel can to the tank? If dirt or dust enters the fuel tank, the fuel tank pipe will become clogged at the bends. We also suggest you periodically check the filter for dirt or clogging.

Check 6   Is the throttle open?   Be sure to turn on the power switch before starting the engine. Then, open the carburetor until the throttle opens a little from the slowest setting. Note that there are instances when the throttle is not open due to incorrect linkage.

Check 7   Is the mixture control screw completely closed?   Is the idle adjustment screw on the carburetor with automatic mixture control mechanism turned in the completely closed direction? If you don't know the current setting of the carburetor, first return the carburetor to its original setting according to the manuals and adjust the mixture control screw after starting the engine.

Check 8   Is the carburetor flooded?   Is fuel flooding the carburetor due to excessive choking? In such a case, first close the needle valve, turn over the R/C car so that the intake of the carburetor faces the ground to drain excess fuel, then dry the inside of the carburetor.

Check 9   Has fuel penetrated the cylinder?   If fuel has entered the cylinder, the recoil starter cannot be pulled. Pulling the recoil starter in this state will damage the engine. Remove the plug and crank the engine to drain the fuel, then dry the plug before use.

Check 10   Is the battery for plug heating fully charged?   Be sure to check that the capacity of the starter battery is sufficient. The easiest way to check this is to connect a spare plug and see if the plug glows red. It is also necessary to check that the pocket booster is fully charged.

Check 11   Is the booster cable functioning normally?   It is possible there is a break in the cable. Dirt or foreign matter may clog the socket connecting the plug causing a problem where the contacts do not touch the plug. Special care is necessary for heavily used cables or for use on dirt fields.

Check 12   Is the plug worn out?   The plug wears with use. Be sure to check the plug before use. The end of the plug's service life is near when the filament is a dull white. We recommend the plug be replaced early so that the engine does not stop during operation. A periodic check of the plug is recommended.

Check 13   Does the recoil starter operate normally?   If no resistance is felt when the recoil starter is pulled, it is possible the shaft is slipping inside. In this case, the slipping shaft can be fixed by applying a spray cleaner between the ropes of the recoil starter.

Check 14   Is the flywheel attached properly?   If the starter motor is used and the lock nut on the flywheel is loose, the compression is stronger and the resultant slipping makes starting impossible. It is also possible the rotation is impeded because the clutch shoe related parts are loose.

The engine stops in no time.

Check 1   Is there a sufficient amount of fuel?   If there is only a little remaining fuel left in the tank, the tank will soon be empty. The 4-stroke engine has good fuel efficiency and the running time is slightly longer. However, the fuel efficiency of the 2-stroke engine is not good. Always try to keep the tank filled with fuel.

Check 2   Is a compatible plug used?   It is essential to use a plug that is recommended in the manuals. If a plug having an extremely different temperature range is used, problems such as sudden stopping of the engine as soon as the throttle is operated, erratic idling, or premature plug wear may result.

Check 3   Is there any danger of overheating?   If the needle valve is closed too much for a lean mixture, the cooling effect by the fuel drops and the engine overheats. In the worst case, the cylinder will seize. Therefore, the needle should be carefully set.

Check 4   Are there any loose or cracked engine parts?  

Is the engine head or carburetor fixing screw loose so as to cause compression leaks or suction leaks? Perform proper tightening while taking care to prevent uneven and inadequate tightening. Furthermore, at the same time, check to see that no parts are damaged.

Check 5   Is the fuel tank properly secured?   If the fuel tank resonates with the vibrations and the fuel foams abnormally, the engine may stop on rare occasions. This is caused by a large amount of air being mixed in the fuel transfer tube. The fuel tank should be securely attached.

Check 6   Does the engine stop immediately after being started?   Once started, let the engine run until the rpm stabilizes without turning off the plug heat. When first starting a cold engine, the engine sometimes suddenly stops as soon as the electricity is turned off.

Check 7   Does the fuel pass normally through the fuel tube?   Clogging of the fuel system will hinder stable engine speed. It is important to periodically clean the fuel lines. If the fuel system becomes clogged when the needle valve is set lean for high rpm engines, there is a danger of overheating.

Idling is irregular.

Check 1   Is the proper plug used?   If the compatibility between engine and fuel is poor, a stable combustion state cannot be created and this will affect the idling. Be sure to use the plug number recommended in the manuals for the engine.

Check 2   Is the fuel compatible?   Although fuel compatibility is important, it is not as strict as plug compatibility. However, if a special application glow fuel is used, such as a fuel with an abnormally high nitromethane content or low oil content, stable idling cannot be expected.

Check 3   Is an appropriate load applied?   If the flywheel is abnormally light, the idling may become irregular. Since stable idling cannot be expected when the shaft or primary reduction gear slips, such as due to a loose lock nut, it is necessary to check the related parts.

Check 4   Is the needle valve set correctly?  

The setting of the needle valve only at maximum rpm is insufficient. Once the needle valve has been set at maximum rpm, it is important to check that the engine runs steadily at all rpm ranges by operating the throttle.

Check 5   Was the mixture control screw adjusted?   For a carburetor with the automatic mixture control mechanism, the carburetor should be set with extra care. Designed chiefly for steady idling and improved throttle response, the mixture control screw adjustment is meaningless if the carburetor is not set properly.

Check 6   Is the muffler detached?   If the muffler is detached or loose, the idling becomes erratic especially when the muffler is detached from an engine fitted with a tuned pipe. The muffler should be attached properly since the same symptom may occur for regular engines.

Maximum rpm is not attained.

Check 1   Is the needle valve properly set?   The needle valve is first set so that a high rpm is reached when the rpm stabilizes after the engine is started. The air-fuel ratio is not optimum at starting so that no matter how much the throttle is opened the maximum rpm is not attained.

Check 2   Has the engine been properly broken in?   Although the engine will run without a break-in period, it is preferable to perform proper break in or running in to attain optimum performance. If break in is performed with care, the engine's maximum rpm can be attained in a shorter time.

Check 3   Is the plug appropriate?   The use of a recommended plug for each engine is assumed. However, it is possible that the use of a 4-stroke engine plug for a 2-stroke engine and vice versa may improve both the response and maximum rpm. In short, the important thing is whether or not the characteristic of the plug is compatible with the engine.

Check 4   Is the linkage correct?  

Even if the throttle of the transmitter is set to the high end, the carburetor could stop midway due to an incorrect linkage. Do not forget to check the throttle linkage during assembly and before operation of the R/C car.

Check 5   Is the muffler securely connected?   If the muffler or manifold is detached or if the set length is incorrect for the tuned pipe engine, the set position of the needle valve will be incorrect. An incorrectly installed manifold will cause symptoms that are difficult to troubleshoot.

Check 6   Is the load appropriate?   At a gear ratio for which the load is too heavy, the engine's torque band and power band will exceed the operating conditions and the engine's true performance is not realized. It is preferable to draw out the engine's true performance by using it at an optimum rpm and under appropriate load conditions.

Check 7   Is there any problem with the fuel?   Also, is a special mixture of fuel used that doesn't match the characteristics of the engine? With an optimum basic combination of engine and fuel as a standard, a fuel containing a little more nitromethane may be tried.

Response is poor.

Check 1   Is the plug compatible?   If the plug temperature range is not of a compatible value, a stable rpm will not last. Furthermore, a worn plug will not only cause poor starting but also adversely affect throttle response. Therefore, periodically check the condition of the plug and replace it with a new one if worn.

Check 2   Is the needle valve properly set?   Although it is essential to adjust the needle valve for maximum rpm, once the needle valve has been set, the response should be checked by flipping the throttle, etc. In particular, the idle adjustment screw greatly influences the response in the low rpm range.

Check 3   Is the programmable throttle exponential adjustment set properly?   If the throttle exponential adjustment function is used and set incorrectly, there will be some play in the change in rpm with respect to the stick and trigger. It is preferable to carefully check the programmable throttle exponential adjustment.

Check 4   Is the linkage correct?  

Since the throttle control servo for the R/C car is used in combination with the brake, check that there is no interference with the linkage. Be sure the carburetor lever moves together with the operation of the throttle.

Check 5   Is the needle valve checked while the engine is running?   The needle valve should be set not only right after the engine is started but should be reset and repeated after the engine has been run for a short time. The setting at the initial position will shift as the temperature rises. Thus, the needle valve should be set carefully.

Check 6   Are the manifold and muffler securely connected?   Car engines are designed for high rpm. If the manifold and tuned muffler do not have lengths that are tuned to the pulsation of the intake and exhaust, the engine's true performance is not produced. Even if a standard muffler is used, care should be taken in its installation.

Check 7   Is the gear ratio appropriate?   An extremely high gearing causes an excessive load to be applied and only damages the engine. As a result, the optimum power and torque band cannot be utilized. First set the transmission to a standard ratio and then proceed to the next step.

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