G'Day all,
I'm going though the process of repairing a Honda push mower that went from running fine to not starting with little no warning.
There's a lot I've looked at to get to this point (new carb (had a spare)), checked ohms of coil (under 9k), new plug (twice), new fuel (with tank drain - twice). I couldn't get the flywheel off (don't have a puller) and soaking the stem in wd40 overnight before trying to tap it free with a wooden mallet proved fruitless. I was able to confirm that the magnets lined up perfectly with the coil pickups at TDC so am satisfied the timing is correct. Then checked compression. I didn't start with compression because it wasn't smoking, started perfectly previously and gave no warning - literally one start to the next a month later - running to not starting, AND I had to borrow a compression tester
. Once I checked compression I thought I was using it wrong - it was zero. Then remembered the decompression valve, so removed rocker cover and took out both pushrods. Compression test then went to 30 to 35 psi. Okay better, but still a problem. Teaspoon of wd40 in the combustion chamber and it came up to 40-45ish after a few pulls. I was about to right it off as rings when I heard something as I turned the flywheel by hand: When near TDC with the rocker cover off and the push rods out, I could hear air hissing past the valves. I was going to check the head gasket anyway, so I spent the extra 5 minutes and took off the head. Gasket/head was good with no sign of damage. Chamber was okay, minimal carbon. I popped of the retainers and valve springs and checked the seats. Honestly, very minimal wear - almost no pitting and even surfaces. I'm going to lap the valves/seats with some course paste and a bit of elbow grease and see if the compression improves. But before I do I'd like to know if anyone thinks the hissing air past the valves on hand turning at TDC is normal?
I'm not going to crack the head and rebore a 120 and replace rings, but if I can get it running before that point then I'm all for it.
Appreciate some advice if anyone wants to chime in!
Cheers to all!
I'm going though the process of repairing a Honda push mower that went from running fine to not starting with little no warning.
There's a lot I've looked at to get to this point (new carb (had a spare)), checked ohms of coil (under 9k), new plug (twice), new fuel (with tank drain - twice). I couldn't get the flywheel off (don't have a puller) and soaking the stem in wd40 overnight before trying to tap it free with a wooden mallet proved fruitless. I was able to confirm that the magnets lined up perfectly with the coil pickups at TDC so am satisfied the timing is correct. Then checked compression. I didn't start with compression because it wasn't smoking, started perfectly previously and gave no warning - literally one start to the next a month later - running to not starting, AND I had to borrow a compression tester
. Once I checked compression I thought I was using it wrong - it was zero. Then remembered the decompression valve, so removed rocker cover and took out both pushrods. Compression test then went to 30 to 35 psi. Okay better, but still a problem. Teaspoon of wd40 in the combustion chamber and it came up to 40-45ish after a few pulls. I was about to right it off as rings when I heard something as I turned the flywheel by hand: When near TDC with the rocker cover off and the push rods out, I could hear air hissing past the valves. I was going to check the head gasket anyway, so I spent the extra 5 minutes and took off the head. Gasket/head was good with no sign of damage. Chamber was okay, minimal carbon. I popped of the retainers and valve springs and checked the seats. Honestly, very minimal wear - almost no pitting and even surfaces. I'm going to lap the valves/seats with some course paste and a bit of elbow grease and see if the compression improves. But before I do I'd like to know if anyone thinks the hissing air past the valves on hand turning at TDC is normal?I'm not going to crack the head and rebore a 120 and replace rings, but if I can get it running before that point then I'm all for it.
Appreciate some advice if anyone wants to chime in!
Cheers to all!
