Wow, I think you run out of easy fix!!! Did you check for cracks on the fuel lines? crack on the block that separate the carb from the hot cylinder? Now you are getting into more difficult things like leaking vacuum seal around crankcase and bearing. Also seal between the cylinder and the crankcase. Setting up test for that is not as easy. Someone here might have an easy way that I cannot think of. One thing you can try is removing the spark plug and turn the engine by hand. If you have a good vacuum seal, you should feel resistance on the down stroke, not as hard as the compression ( up ) stroke. Maybe with some soap solution around the seal and turn the engine to see any bubbles. Someone might have better ideas other than to hook a pump to the intake or exhaust port to pump. If all else fail, maybe is time to think "new toy"!!!

I bought a Troy-Bilt strairt shaft weedeater and brush trimmer combined. I used this for five years without any problems,starting or otherwise. . Last year it would not start. So I bought another Troy-Bilt of the same model.They both are 4 cycle engines. I had some trouble starting the new one so I took all the gas I was using out of it (87 octane) and switch to (91 octane),Now it starts great and runs smooth. I also have two macholic 2 cycle chain saws that had the same starting problems..I switched to the 91 octane gas with the same oil mixture and now they both start fine.

I am suddenly out of sync with the “Boards” and try to get info in when I can. This is a concern and I have questioned my “Drs” since age 70 (at 72 now) I had a good 36 year career and my few absences allowed me to receive credit for 40 years of service at 57 years of age. My memory is starting to challenge me. I have met fellows less than 70 that did not know their age. I have spotted friends walking and knew they were off course and got them home. I stopped “Traveling and Fishing” when I realized was getting confused or forgetting simple matters. I walk 2 miles 5 week days and work projects and maintenance 2-3 days 2-3 hrs a week. That is down from walking 4 miles 5 days and working or volunteering all day My First 10 Years Of Retirement. “I Might J Just Be Tired” LOL! The Arc welder is up and running w/o finding a reason. After trying a different AC source and another AC Welder I knew mine should work and it did. The “Rods that would arc and stick, Started Continuing To Arc”. I can only say “It Was A Bug”! My rods were stored in a double wall Military Shell Container. Downsizing they are sealed in smaller sealed container, with like new flux. I’ll hope to find some answers with my issues or I’ll get off the 3 Mechanical Boards “Before 90”!.

I've got a couple of Homelite Bandit SX-135 (UT20601). Bought the first in 2001 as a cheapy to back up my Echo SRM2100. Had problems with running to lean and ended up prying off the mixture screw limiters to allow for richer mixture. Also added Seafoam to the fuel to gradually dissolve out the gum. Got almost 20 addition years out of the machine. Been keeping the second as a parts machine. As for the choke, easiest thing to do is take off the air cleaner cover and remove the piece of foam. You should be able to see the choke butterfly and by moving the lever you can now see the "run" position and the "choke" position. As for the string head, mine came with a single string .065 head. I ended up transplanting a dual head and winding it with .080 line. I don't bother with the bump feed; rather I momentarily shut down the engine, and manually advance the line. With the heavier line and dual string I can go quite a ways without advancing line, unless I am working around a chain link fence or edging against concrete.