outboard compression

Seems a little low, but at least they're all pretty close to the same reading. I would try running something to clean the carbon out of it, that should raise the compression some too. Could also be a carboned up exhaust tube.

IMO the compression may be a little low, but every motor is different. It could very well be in the correct range for that motor.  So anyones guess is mearly speculation.
 
Your best bet is to buy the maintance manual its like $30 and it will you get the specs on everything for that motor. Very well worth the money.
 
If the motor is running but running poorly i would not jump to compression as the smokeing gun. Start with the basic things first, check the plugs, spark, and fuel, possibly fuel line (the fuel line could be rotting inside and havin flakes or flaps blocking the line starving the motor of fuel) or fuel pump. You might be running the motor on 3,4,5 cylinders. All very easy to check.
 
Just because the plugs are new does not mean they are good, back in the day getting a plug that grounds out internally was rare, but any more it is very common (i see a few each year)
 
Thats where I would start. I ran a motor similiar to your it was an old merc tower of power middle 1980s that I learned alot from. If you need some help feel free to PM with questions

www.marineengine.com is a great resource, you will be able to find out the specs for your motor there as well.
 
We had the same issue with a Merc Classic 50 and after spending much cash on chasing things that "professional" mechanics did, I started to tear it down myself and found the exhaust tube nearly plugged with oily carbon build up. The fix cost almost nothing. Since that time I have done all of my own work on our collection of boats. Really wish a good marine mechanic was easy to find...

Find out the rec range for WOT. That seems like you have a to agressive prop on that motor.
 
What you describe about how it is acting fits an issue with the prop.

The boat/motor was purchased last year but it is spotless. We were told that the owner had health issues so never really used it. When we cleaned the cylinders we did have alot of carbon come out of the exhaust. Now when ran through we get no black at all.

How do we find which prop that motor should be using?

Also since we were cleaning that motor we were changing plugs on 9.9 kicker. We have the manual but it doesn't say what gap to set the plugs at. What should we set them at?

Thanks guys!!!

First find out your WOT range. Very important.
 
The high five prop really thows a wrench in the puzzle right now (because the SS and having 5 blades).
Do some looking online at different forums Iboats has a good one, do a search for your motor in thr prop section, keep grinding the search function. You will piece together about what you should expect from the motor, and a good starting point for props.
 
If your motor starts and runs smooth, then I would stop trying to fix what isnt broken. Also I wouldnt get to hung up on how clean your motor is from carbon internally. In some cases that would be an issue, but under normal everyday conditions is doesnt hurt anything.