OS 4 Stroke .91 low speed needle setting
05-04-2013, 06:56 AM
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OS 4 Stroke .91 low speed needle setting
This is an older Surpass: Can someone tell me how many complete turns to turn out the low speed needle screw from closed to come to a setting to begin adjustments from? Thanks.
05-04-2013, 07:16 AM
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RE: OS 4 Stroke .91 low speed needle setting
Start up setting is about 2 turns out on the high end and 1.5 on the low end. You set the high speed needle so the engine is about 300 to 500 below max RPM then you adjust the low speed needle until the engine is idling well and there is no sag or stumble and the engine doesn't die when the throttle is opened quickly. If it dies right away the low end is too lean, if it stumbles it is too fat.
Another way is to leave the glow driver on the plug and the engine is idling well, remove the driver, if the engine looses rpm then it is too fat, if it dies it is too lean. These ways it will get you close so you can fine tune.The tune on the ground is often a bit different then when the plane is in flight and the engine is unloaded.
Another way is to leave the glow driver on the plug and the engine is idling well, remove the driver, if the engine looses rpm then it is too fat, if it dies it is too lean. These ways it will get you close so you can fine tune.The tune on the ground is often a bit different then when the plane is in flight and the engine is unloaded.
