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| techtalk:evo:carb02 [2024/07/01 22:20] – [Interaction of Jets & Ports - A Balancing Act] ixl2relax | techtalk:evo:carb02 [2024/07/01 22:27] (current) – [The Idle Drop Method (IDM) for Setting Idle Fuel] ixl2relax | ||
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| ==== The Idle Drop Method (IDM) for Setting Idle Fuel ==== | ==== The Idle Drop Method (IDM) for Setting Idle Fuel ==== | ||
| - | The Idle Drop Method (IDM) will help find the right setting for the Idle Mixture Screw (IMS) to supply the proper fuel mix to the Idle Port.((see the chrishajer thread link below)). At idle, the engine will have difficulty if the idle fuel mix is too lean or if the idle fuel mix is too rich. There is a small range between those excesses, which is the point of this adjustment. This procedure does require the correct Slow Jet, so you may need to change the Slow Jet if you cannot find the described idle range while performing the IDM. | + | The Idle Drop Method (IDM) will help find the right setting for the Idle Mixture Screw (IMS) to supply the proper fuel mix to the Idle Port.((see the chrishajer thread link below)). At idle, the engine will have difficulty if the idle fuel mix is too lean or if the idle fuel mix is too rich. There is a small range between those excesses, which is the point of this adjustment. This procedure does require the correct Slow Jet, so you may need to change the Slow Jet if you cannot find the described idle range while performing the IDM. Set the IMS initially to 2-1/2 full (360°) turns out from a lite seat (closed). |
| If you have previously set the throttle plate, between the idle port and the transfer ports, using the Idle Set Screw, you may need to roll the throttle slightly (at the beginning of this process) to keep the engine idle. With the throttle grip, set the idle speed as low as possible, yet still smooth engine operation. Lock the idle speed with the throttle grip lock (rather than changing the setting of the Idle Set Screw, which should still be (as close as possible) between the Idle Port & the Transfer Ports). | If you have previously set the throttle plate, between the idle port and the transfer ports, using the Idle Set Screw, you may need to roll the throttle slightly (at the beginning of this process) to keep the engine idle. With the throttle grip, set the idle speed as low as possible, yet still smooth engine operation. Lock the idle speed with the throttle grip lock (rather than changing the setting of the Idle Set Screw, which should still be (as close as possible) between the Idle Port & the Transfer Ports). | ||
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| - | | **Note - Trouble Finding A Change** - You may still have the throttle plate too far open, thereby running on the Transfer Ports instead of the Idle Port. But, if you have carefully set the throttle plate & still can't find a fall off until below 1/2 turn out, you need a smaller Slow Jet. If you can't find a fall off in idle until beyond 3-1/2 turns out, you need a larger Slow Jet. However, it is not recommended to use a smaller size than 42 nor larger size than 46. If the IMS setting appears to make no difference, you may have other issues. You may have an intake leak or exhaust leak. You may have fuel leaking into the carb thru the vacuum hose because of a defective petcock diaphragm or thru a defective Accelerator Pump diaphragm.((oldboy at Post#7 - https:// | + | | **Note - Trouble Finding A Change** - You may still have the throttle plate too far open, thereby running on the Transfer Ports instead of the Idle Port. But, if you have carefully set the throttle plate & still can't find a fall off until below 1/2 turn out, you need a smaller Slow Jet. If you can't find a fall off in idle until beyond 3-1/2 full (360°) |
