Regarding the fuel lines: I removed the lines, cleaned and inspected them. I couldn't see any holes or tears, they all looks pretty good. The green fuel intake line, I plugged one end, and put the air gun nozzle on the other, stuck it under water, didn't see any bubbles. The test was a little tricky to do, as I'm not sure how the line is made, but pressure seemed to build in sections of the hose causing it to bubble line blowing up a balloon.. so the test may have been a dud, and not accurate. I checked the hose again after that, still seemed fine. Do you reckon I should change it anyway ?
Regarding the Fuel filter: Couldn't find spare (good) filter on hand, but I removed the one in the Stihl, it looks pretty good and clean. I put a bit of compressed air into it, and I could feel it coming out of the filter-mesh. Change anyway ? (see attached pic)
Regarding the spark arrester, I removed the mesh, and it looked fine, not blockages, looked clean (see attached picture). However, I have noticed that running the trimmer without the muffler, seems to run, not well, but doesn't cut out when I off the choke... however, putting the muffler on, it cuts out. I blew air through the muffler and felt it exit, so I'm not sure why it would do that.
Originally Posted by AVB
Widget,
A piece of advice here on these carburetors. Get it ultrasonic cleaned, regular carburetor cleaners can damage the delicate rubber check valves inside the carburetor; plus using an ultrasonic cleaner you don't need to remove the welsh plugs normally though I do remove the mixture screws.
Yes!, I've been definitely looking into getting an US cleaner for a while now . I'm not sure if it's big enough, but I have been keeping an eye out for a small cheap unit that's used for jewlery etc.. but feel it may not be deep enough for trimmer carbs. The other I'm looking at is maybe a larger 6L (give or take), but they're much more costly, so have to save.
Originally Posted by AVB
The metering lever height, it is flush with casing. Use a straight to set this.
Will have a look, though do they always have to be flush? I serviced a Weed Eater the other day, cleaned the carb, and had a look at the lever height.. it's much lower than the casing, but it starts first pull and runs alright. I'll have another look at it hopefully tomorrow.
As for the compression test mention. It only tell only the condition of the cylinder, piston, and rings but will not tell if you have a crankcase air leak. This is what the pressure/vac tests are for. As pressure testing the carburetor, the test will only show if the fuel pump side is sealed and that the metering valve is leaking or not. You can not test the metering side. If when doing compression test. You do it with the throttle held open. If you readings are @ 100 psi or less than you have a severely worn cylinder or stuck rings. From my experience it takes at least 100 psi for a 2 cycle to run correctly[/quote]
Thanks for the tip . I managed to do a compression, holding the throttle open.. it read 95psi. The piston is a little rough (as I'll mention below)
So after inspecting the hoses and spark arrester, I looked into the exhaust port, and there is scoring. I decided to just take the head off and see how bad. I'd say it would need replacement, but is this likely to be the/an issue ?
I pulled it a part, cleaned it, but it back together, and got it to start. I could only get it start by using the choke, but when it started, i flicked the choke off and it stayed on (without the muffler, as mentioned above). I tried messing around with the Hi/Low/idle, but having issues there. The low I could get down, but not too low otherwise it'll cough and end up stalling. I couldn't start it again, even when hot, unless I use the choke... but once started, I turn choke off, and it seems to idle fine. Trying to adjust the Hi screw does nothing now, even turning all the way in it revs so loud/fast (see video).. I can't change that. Now, I noticed there was red gasket material on the lower part of the engine.. I didn't replace that, though should... could having a broken seal there cause a significant increase is RPM ?
[EDIT] Note, after putting it all back together, I noticed the oil/fuel leaking out didn't occur. Looking at the gasket, I'm not sure if it spat out the exhaust due to the scored/stuck piston ring, or whether there was a leak from there. When I removed the head to reveal the piston, I also removed the ring, and cleaned it up, then put it back on and made sure it had movement... perhaps doing that caused it to seal the cylinder better, preventing excess oil coming through the rings ??
Attached are some pics, and links to some video... at this stage I'm ready to shelve the trimmer, as I can't figure out why it's doing it, though could be the piston.. will have to look into whether it's worth buying a replacement.
. I'm not sure if it's big enough, but I have been keeping an eye out for a small cheap unit that's used for jewlery etc.. but feel it may not be deep enough for trimmer carbs. The other I'm looking at is maybe a larger 6L (give or take), but they're much more costly, so have to save.
