Honda 389cc engine binding in one spot

[PTmowerMech]

389CM
Stamped on the block is
1445060
GCBDT
EY7X

This is off of a Honda Generator EB5000X

Trying to pull the recoil and it wouldn't budge. Thought it was locked up, so I pulled the recoil and spark plug. I put a socket on the crank, and accidentally turned it counter clock wise and it turns freely. Turn it the other way, and just before TDC on both the compression and exhaust stroke, it comes into a spot that's really hard to turn over.
With the ratchet, I can get it over that one spot. It doesn't take a huge amount of force. But none the less, still requires some force.
Now when this spot comes up, it doesn't feel like a metal on metal situation. Although it could be a metal against the side of metal.

BTW, the rockers go up and down as they're supposed to.
Also, removed the brushes, which looked a little worn, but OK. Tried spinning the engine over without the brushes attach. Also looked down into the gen motor and didn't see anything that could be binding.

Anyone got any clues about this?

 

[mechanic mark]

https://cdn.powerequipment.honda.com/pe/pdf/manuals/00X31Z238010.pdf

see page 69 & adjust valves with engine cold, check air filter, check oil level on dipstick, fresh gasoline with Star Tron fuel treatment, new spark plug check gap.

 

[Hammermechanicman]

Pull the head and check for carbon buildup. Spin The engine with the head off and see if it binds. Check for something binding on flywheel.

 

[ILENGINE]

Agree with Hammer. A piece of carbon or even the ignition module hitting the flywheel at the magnet would both bind just BTDC.

 

[bertsmobile1]

AS will a screw that has dropped out of the throttle or choke butterfly .
This is the time hen that Bore-0-scope you have been thinking about buying suddenly becomes an essential item.
But get a good one that hooks up to our PC & can look backwards as well as forewards .
Down the plug hole then down the sump drain (after the oil is gone .) can save a lot of time on a rejected repair quote.

 

[PTmowerMech]

Gonna start taking the head off now. I removed the flywheel just to make sure it wasn't a magnet or the coil. And it wasn't. With the flywheel off, I put the nut back on and gave it a turn with the ratchet, and it's still binding up.
So it's gonna be internal.
I can't see anything in the generator motor being the reason for the binding in one place every time.

 

[PTmowerMech]

AS will a screw that has dropped out of the throttle or choke butterfly .
This is the time hen that Bore-0-scope you have been thinking about buying suddenly becomes an essential item.
But get a good one that hooks up to our PC & can look backwards as well as forewards .
Down the plug hole then down the sump drain (after the oil is gone .) can save a lot of time on a rejected repair quote.

I just ordered one. Thanks for the heads up on that. I got the cheap one. But it's waterproof. Connects to my phone. If it works out, I'll get a better one later on.

 

[PTmowerMech]

Pull the head and check for carbon buildup. Spin The engine with the head off and see if it binds. Check for something binding on flywheel.

You hit the nail on the head, brother. Thanks

There was a pile over 1/2 of powdery carbon on the bottom edge of the cylinder. And on the head. It blew off easy. Just a big puff of smoke when I hit it with the air.

 

[PTmowerMech]

BTW, Partstree shows this head gasket as a 12251-Z5T-003. Can I reused this one? And is there another I can use. (Because Stens doesn't have this specific one. But they do have some that look like it. Like the 465785. Which shows it's for a GX390.

Being all metal, I don't feel comfortable reusing the original.

 

[bertsmobile1]

No
Buy an original one
Don't even think of reusing the old one