I have a year old Cub Cadet SC 621 walk behind lawn mower. It has a starting problem. It is extremely difficult to pull start. It appears the compression prevents the starter cord from being pulled. A neighbor suggested, perhaps the carb. bowl might be leaking and letting gas in the cylinder/s. I took the spark plug and no liquid gas is apparent. It pulls extra easy with no spark plug (so it must be compression holding it back). Could there be a compression release not working? Is there such a thing in a Cub Cadet? Help anyone?
My Cub Cadet model 127 (12HP garden tractor from the 70's I think) has compression release. Kohler engine. But that doesn't help you.
If this is your motor, it has compression release:
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I don't think a defective compression release would make a motor "extremely difficult" to pull start - but that depends on your definition of "extremely difficult".
Does it start at all?
If it does, does it belch thick smoke and run very rough for a while?
If it does start, does it pull MUCH easier after turning it off for a few minutes?
Sometimes it's difficult to see excess gasoline in the cylinder head. It doesn't take much to raise pull-resistance a _lot_. I've had a homelite trimmer basically become unpullable due to a carb problem. But, I think compression release would _probably_ assuage even that.
Some mechanics clear floods by pulling the plugs, cranking the motor a few times (caution, fire hazard!), and then squirting in a short shot of methyl alcohol in the cylinder head[s]. Then, let the thing sit for an hour or more (waiting for the alcohol to "dry out" the cylinder), clean the plugs, reinstall, and try starting again.
I had a Cub Cadet mower. Year one was great, year two was getting difficult, year three it went into the trash. It was so difficult to start that one the motor was finally running, I was too exhausted to cut the grass.
I bought a John Deere. Five years old and it started on the first pull, just like always.
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