Echo Chainsaw Model CS-510, 20 inch. Can barely pull rope but freeweels with plug out.

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Apr 13, 2026
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Echo Chainsaw Model CS-510, 20 inch I think. Light usage. After being loaned out I decided after a few weeks to run all the gas out of the carb. Could barely pull starting rope. With plug removed it free wheels. Removed muffler to check for carbon build up. I see none. Cylindar and piston look good, looking through the exhaust port. Removed bar adjustment panel to be sure the brake was not catching. Same problem. Checked pull rope pulley. Has a little play on the center shaft, but I don't believe it's enough to bind up. I can turn the fly wheel with two fingers with the plug in. Much easier with the plug out. Any ideas?
 
Make sure the correct sparkplug is in it! Too much reach and it could be acting as a piston stop.

Also leave it upside down with the plug out and see if you get oil/fuel running out, in case its flood/hydrolocking.
 
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Can you start it? I have a CS-510 always thought it should of had a compression release for starting. Mine has a fair amount of compression. I'm wondering if you have not started it in sometime and forgot how much compression some these 50cc saws have. Honestly I would much rather start my old 046 magnum with the compression release than my CS-510 especially now that i'm older. :LOL:
 
Is it compression type resistance or a mechanical type resistance? If compression type, does it actually have good compression? Could be a problem with the comp release button if you're getting 120#+. Mechanical type, check the clutch, weights, and springs that they are spinning free and not binding on anything (like the bar). Also, with the rewind mechanism off, does the rope pull smoothly? One last suggestion if you want to keep your tools in good working order, DON'T LOAN THEM OUT 😁.
 
That saw has some compression? Maybe spray some silicone lube into the starter coil and see if it just got a bit sticky?
Pull rope pulls easily when fly wheel cover is detached . I'll try some silicone spray but I can't see where the rope pulley may be binding on the shaft.
 
Pull rope pulls easily when fly wheel cover is detached . I'll try some silicone spray but I can't see where the rope pulley may be binding on the shaft.
 
Make sure the correct sparkplug is in it! Too much reach and it could be acting as a piston stop.

Also leave it upside down with the plug out and see if you get oil/fuel running out, in case its flood/hydrolocking.
Correct plug is installed.
 
Is it compression type resistance or a mechanical type resistance? If compression type, does it actually have good compression? Could be a problem with the comp release button if you're getting 120#+. Mechanical type, check the clutch, weights, and springs that they are spinning free and not binding on anything (like the bar). Also, with the rewind mechanism off, does the rope pull smoothly? One last suggestion if you want to keep your tools in good working order, DON'T LOAN THEM OUT 😁.
Compression resistance. No resistance with plug removed. Acts the same with bar/clutch cover/brake removed.
 
Compression resistance. No resistance with plug removed. Acts the same with bar/clutch cover/brake removed.
Is there a lot of carbon on the spark plug?
Unless the head is packed with carbon, I can't see what would be causing this.

It might be too much saw for you?

My husky 390xp is an 88cc saw with compression release, but I can start the saw with out using it.
 
Since I'm old now with arthritis in my hands, shoulders, etc. I have a hard time pulling over my small engines on a bad day. It could be over fueling or maybe flywheel key is sheared and trying to fire against you? Try taking out the plug and see if fuel mist comes out the hole.
 
HooRah! Last resort berfore going to the small engine shop. Removed the screw from the starting rope pulley. Forced some silicone crease down around the shaft. Sprayed it with silicone. That sucker starts and runs. Pulls harder then when new but I can start it. Next I will replace the starter rope pulley and shaft. Thanks for all the advice.
 
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