Always consult your owner’s manual for specific Carburetor tuning and recommendations. Understanding how to tune your carburetor properly not only will improve performance, but will aid in avoiding engine seizure. A Homelite chainsaw carburetor adjustment can be done at home, but performing this procedure yourself may void your warranty. Under the extreme conditions of a clogged idle port and channel, it may be necessary to remove the welch plug. Same thing when got it back on. I have idle turned down to 900 rpm. First you'll need to find out what carb is on it so you know which kit to buy. Above is a trouble-shooting guide that can help you diagnose engine problems that can often be mistaken for the carburetor. If you use any fuel with ethanol that would be the first thing I would look at. After the engine warms up the idle can be fine tuned for optimal performance. It is also important to follow safety precautions when making a Homelite chainsaw idle adjustment, because the chainsaw will be running. Steady stream while engine cranks. and the carburetor will always run too rich or too lean. Sometimes, your chainsaw will only idle for about 5 to 10 seconds after you let off the throttle and then it will shut down. Is it a sticking valve? The low pressure draws the fuel and air mixture through the first idle hole into the engine. Engine compression and crankcase vacuum are to manufacturers specs. The center tip that fits into the metering lever hole must be secure. I have a khohler 20 hp vtec engine I t will start when I put fuel in it and shuts off when it burns off. Required fields are marked *. (M) Metering chamber: Fuel reservoir, feeds fuel to the main nozzle. Any input would be great. The latest issue……..–having replaced the carb, the gas filter, the plastic ‘purge bulb’ and a new It makes a difference. (N) Throttle valve: Regulates engine speed, as controlling the air volume mixed with discharged fuel from the main nozzle. i have been trying to get a kohler ch6 going for a friend. If the carburetor is equipped with the plastic filling in the idle chamber, it will be unusable when the welch plug is removed. Stihl Chainsaw Carburetor Adjustment. 27506 kohler pro 18 hp ohv gas is leaking from gas tank to oil. I have replaced fuel tubing, new carb, cleaned fuel tank, still same problem. After rebuild my fz16 motorcycle engine, I,m facing a painfull problem, when I start my bike or riding, my rpm gose down for a moment and came back again, its like starving for fuel. As the engine runs, fuel is being drawn from the metering chamber in the carburetor. We have changed the carb out along with the fuel pump and filter and still does the same thing..any other ideas ??? Inspect pump diaphragms and gasket, replace if they show any signs of wear, wrinkles, curling or tears. The choke has to be almost closed to run and stay running, but won't idle period. Repair kits are available, but buying a whole carburetor is a much better option. I removed the carb and had it rebuilt for an external leak at the Can take the unit for warranty service but there is a 3 week backlog. If your Echo 413H leaf blower is performing sluggishly or is idling too low, causing consistent stalling, you may need to adjust the carburetor. I took the carb completly apart and cleaned it. If the check valves cannot be cleaned, replace the start pump body. I bought a new countryline log splitter with the Koehler 6.5hp. Turned the petrol on and it started. Filled with gas. The gasket goes on next to the start pump body, with the diaphragm on top of it. Hi zeeshan, This chart is intended to be a helpful guide when troubleshooting your carburetor. This season I started my lawn mower on the second pull and it cut beautifully. If the carburetor is equipped with a plastic disk, install it onto the metering lever by placing the molded tip into the hole in the free end of the metering lever. i have cleaned out the carby, and replaced most of the hoses etc. I have a 1972Honda Cb500 four and for some reason my number 4 carb/cylinder seems unable to pull enough air through it to allow me to sync it to the other 3 in a dynamic sync. Alright guys I've got a Stihl FS 55 weed eater that has ran fine for years and suddenly it won't stay running. I have spent a fortune taking it in and as soon as they get it started they think that it is ok, but it clearly isn’t. Engine will not start using choke,will start manually choking with your hand what is theinitial carburetor settings. Thanks for assistance -Mark N. Sounds like the needle is not seating and/or the float needs replacement. The outlet check valve should offer resistance to airflow. I was told by the guy who gave me advice over the phone that he has machines that are over 20 years old and are still running with the same engine and valves.. Is it basically a case of the engine not processing the fuel properly? Inspect the operation of the throttle valve and lever. Over time, however, the carburetor will need adjusting to maintain that optimal setting. A strait edge can also be used as described on the next page. (filter not plugged), Fresh gas.. Did you figure out what the problem is? (C) Fuel pump inlet check valve: Opens during a negative pressure pulse. The vacuum from the expanding bulb draws fuel through the inlet check valve from, The vacuum in the metering chamber draws in on the metering diaphragm, and lifts the inlet needle. Took the bowl off, full of gas. As the Start Pump receives the crankcase pressure and vacuum pulses, it begins to suck fuel from the metering chamber into the start pump and spray it out of the injector hole in the throttle bore. my problem is that i can get it to start and run but only if the choke is fully closed. If the welch plug is oblong shape, press it firmly with oblong punch. Install the gasket, fuel strainer cover and screw. Any Suggestions? You can find Briggs & Stratton Repair Manuals under our Manuals category. Currently you have JavaScript disabled. any suggestions? When the purge bulb (A) is released, the outlet check valve (C) closes and the inlet check valve (B) opens to draw fuel from the metering chamber. If you notice gas dripping from your carb, or if the idle gets unreliable, replace the needle valve and adjust the lever even with (or slightly below) the carb housing if you don’t have a gauge. Do not use wires or drills to clean orifices. Your email address will not be published. Lay the main welch plug into. Solution #2: Poor idle quality can be caused by a vacuum leak. We have some pretty knowledgeable people on our forums that might be able to provide you with some detailed help for your issue. Is it needle valve issue, sounds like its NOT getting enough gas Mantis tiller- carb won't prime. The pressure of the metering diaphragm against the lever over rides the spring pressure on the inlet needle. being careful to un-hook it from metering lever. If the engine is not accelerated or if the engine drives at high speed, lacks power, then main mixture should get adjusted. (LA) Idle Speed screw – This controls the engine speed at idle. Usually it appears frequently between 2 to 3.5k when I throttle or goes to change the gear. They are marked "H" for the full throttle adjustment and "L" for the low speed adjustment. After the engine starts or “pops” and dies in the full choke position the choke valve is then moved to the half-choke position. Hi, I have a Mantis tiller with a Zama C1U-K54 carb. Do you have a kit for that? Does anybody know why my motor only runs when I blow in the Overflow on the bottom of the carburetor. i was told this was normal as fuel is backing up. If metering diaphragm is hooked type, remove it. New cub cadet ZTR with Kohler 24hp 7000 engine 3.5 hours, Ran out of gas while mowing. Air enters the secondary holes on the atmospheric side of the throttle valve and mixes with the fuel in the idle pocket creating an emulsified air fuel mixture. I cleaned the carb and looked at the float and float pin for wear etc and it all looked good……no leaks in the float. The end of the metering lever should touch the gauge. Having difficultly installing Tube Pick Up part number 391813. Pls some one help me. Tried heating plastic to expand but unsuccessful. Rotor assembly should not be broken or worn. If the outlet check valve is sticking open, it can be cleaned with a spray carburetor cleaner. Opened it up to take a look, and as I opened up the top part with the float,a piece of the gasket fell off,like it had a tear on it. If the metering lever is too high, push down on the free end of the lever, then carefully push down on the inlet needle, if the metering lever is too low, pry up carefully on the free end of the lever. DO NOT BLOW COMPRESSED AIR THROUGH THEM. The “venturi affect” occurs when airflows through a constriction, the airflow speeds up (velocity increases) and the pressure decreases (vacuum increases) at the point of the smallest diameter. The secondary idle holes are now on the vacuum side of the throttle valve and fuel is drawn. I have a two cylinder Briggs and Stratton build Craftsman ELS 725 22 HP engine on a riding lawn mower. Note that both the low-speed adjust circuit and the high-speed adjust circuit draws fuel from the lower chamber.