Hard pull with plugs in

Greetings all,
I did a search and saw a post where someone was experiencing this exact issue, but there were no responses/suggestions on their thread... Hopefully someone has experienced and resolved this.

1973 18 HP Evinrude - Came with the boat, not running.

With the spark plugs in, I can maybe pull the cord halfway before it resists to the point of almost ripping my arm out of socket... Doesn't really lock or bind as I can heave on it and get it to come out a little more...

Removing either of the spark plugs (#1 or #2) does not resolve, but removing both allows it to pull normally.

Plugs in it were Champion UJ-81J's and I replaced them with Champion J4C based on what I found via searching the forums. Problem still exists.

I found on a Google search where someone suggested pulling the exhaust cover and making sure all the ports were open and clear... I did that and, with a little maintenance, all ports are open. Problem still exists.

I saw another thread where someone said they 'tinkered with the flywheel and got it fixed'. That was the extent of their description... Can anyone shed any further light on that course of action, or offer another suggestion to help fix this?

Oh, hooking a battery to the starter acts the same way...

Any thoughts?

A electric starter also encounters strong resistance in cranking the engine over with the spark plugs installed? If so, I'm wondering if the cylinder head has been milled.... increased compression to an extreme point?

I agree on to many milling downs of the heads.................Unless you are not a strong enough persen.
My 9.9 really a 15 hp. I can pull start with 2 fingers on the pull handle. I am 75.

Do a compression test.

How do I do a compression test if I can't pull past halfway?

A thought..... are the pistons hitting either of the spark plugs perhaps?

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Pistons don't appear to be hitting the plugs... Hard pull with plug wires off as well...
I took the pull start housing off and was able to turn the flywheel completely around slowly with a socket... The faster I would start to turn, the more resistance I felt...
I'll try a compression test tonight...

Unless somebody has modified the motor as has been suggested, or is hydro locked, I have to suspect the problem is you. The normal compression strokes will make it hard to pull as each piston goes through it's cycle. I will have to take that back if it turns out that your are a big husky guy. Have you ever started similar motors? Saying all this with no clue who you are, and not meaning to put you down or insult you in any way.

Maybe he should try my 1958 18 hp 'Rude. That one needs 2 hands, and a foot on the cowl to pull start it. Only thing I have harder to pull is a 58 35 hp.

Got her running...
Thank you to the poster who suggested the electric starter with the plugs out... I shot a little oil into each spark plug hole and hooked up the starter... That freed up whatever was causing the problem. Put the plugs back in hooked up the tank and plug cables... Voila! Fired right up!
And thank you to everyone that suggested the electric stater and I start working out... I'll sign us both up for the gym... lol

Electricity is your friend, at least with starting outboards. I just found a starter and bracket for my 1958 'Rude 18 hp. It only took about 4 years to find it.