I have a Echo gt 1100 trimmer that I've recently rebuilt the carb on..It's a zama c1u k29a
-used the full rebuild kit RB-21
-Cleaned the carb with a few cans of carb cleaner
-replaced primer,gas line,fuel filter
Here's the problem
-I can set the low needle and it will idle fine..but when I open it full throttle it dies out almost instantly as it shoots to fulll throttle.
-I've adjusted the high needle multiple times, taking it 2 turns out, then all the way in 1/8 turn at a time........... then I tried 3 ,4,5,6 turns out it seemed like and it hits a point where it just wont start/idle period if I go richer
You must set the high speed needle first, then the idle. Start each needle 3/4 turns out from lightly seated. Reclean the high speed passage and make sure that the high speed needle is not damaged. Also, check for air leaks between the carb and block. Finally, if it is bogging down on acceleration you need to open the idle needle, not the high speed.
In addition to what Rivets said, check your metering lever height. I recently had one that the metering lever was set too low from the factory and would not let enough fuel in to run the engine at high speed. I tried adjusting the high speed needle, just as you have, and it would not respond until the metering lever was set correctly. Also, check your exhaust port, spark arrestor screen and muffler for any restrictions - correct as necessary.
This might sound silly, but does your muffler have a fire screen in it? If so, remove the fire screen and muffler. Many times these fire screens get clogged from the oil mix. MANY times I have found by looking into the exhaust port and rotating the crank, you can see the piston moving through a tiny pinhole of carbon that has built up in the exhaust port. Carefully clean this out then blow air through the spk plg hole to remove any carbon that might have fallen into the cyl. An exhaust port that is blocked will give false thoughts as to what is wrong and seems like a carb problem. with some experience, with the machine running and putting your hand where the exhaust comes out of the muffler, you can feel if there is little or normal exhaust coming out
I recently figured out what the culprit was, It's the freely swinging plastic choke located inside the air filter. As soon as the engine hits its peak, the choke swings up and kills all air to it... not quite sure how to adjust it since it just hangs there freely swinging..and it appears to be designed/manufactured this way....any ideas guys? I'm about to just remove the hanging arm and be done with it.
Before you remove the choke, try starting the engine when it is cold and without the choke. If your engine will start cold without the choke the go ahead and remove it but keep in mind that the engineers designed it with a choke for a reason. Most choke systems have some kind of detent to hold the choke in place when open or closed. See if the problem is with the detent and if it is maybe you can rig something to hold the choke open once you get the engine started.
If I recall correctly, most Echo products have the choke as part of the air filter housing and that part is easily replaced for around $10.00 give or take a little.
