Hard to pull starter cord - 75 Merc 200 (20hp) with manual start - help me get this running

Members -
Need advice on bringing a new-to-me, 1975 Mercury Thunderbolt 200 (20hp - 1200225) to life. I had a thread going "advice on starter assembly" but after a week of tinkering and replacing the many tiny wave springs, friction springs and a missing part - I have the starter assembly operating (it will engage flywheel). Now to next issue...

Though the starter pawls now engage the flywheel, it is almost impossible to pull the pull cord. With both plugs in, I cannot get the engine to turnover via the pull cord. With the plugs out, the cord, flywheel and pistons seem to cycle perfectly. I believe the engine ran less than a month ago and has had regular service. I sprayed a little carb cleaner and lube in the spark plug holes and worked the cord some more, but the effort remains difficult/impossible with plugs in.
What should be my next steps???

I've already:
1. ordered a shop manual,
2. crawled these forums,
3. hit the gym 4-5 days a week so, don't infer that my physical strength is an issue.

I was told the motor has new plugs, carb rebuilt, head gasket replaced, water pump and lower unit refurbed.

I am new to 2 cylinder repair, so don't assume. Thanks in advance!

CigarXO

There is a water jacket gasket.-----There is no cylinderhead gasket on this motor.

Racerone - and how does making a correction advance my goal in fixing this engine... there are 3 filaments labeled "cylinder gaskets" of one type or another here: http://www.marineengine.com/parts/mercury_marine_parts/sn/04288253/ 1200225/464_80, none are labeled "water jacket gasket". Mute point. The point was to help describe the state of repair or disrepair for those more knowledgeable in repair than I. Use the information for constructive progress or don't comment. Such wasted replies are what make crawling threads so frustrating and inefficient.

Anyone else?

Bump.... Anyone?

1. Timing?
2. I've seen mention of a hole in the chamber in some models to reduce crank pressure getting clogged; but, I can't identify on this model?

Thanks in advance!

There likely is nothing wrong and the motor just has lots of compression.

Had that problem on a 200 that I worked on--it was a BEAR to pull start. Problem turned out to be two bad ignition coils. When I changed them, it started easy and ran great.

Jeff