Supposedly the Pa rangers are checking 20 hp motors on Pa lakes with 20 hp limits like Lake Arthur.  The fine is over $300.  I do not know if they started to check Pymy for 9.9 hp.  A local Pa boat dealer has a couple of  used 25hp Hondas and Mercs  with 20 hp stickers on them for sale.  It seems that with the crackdown many are trading their stuff  to get legal limits.

I know Ill sleep better now that the fish gestapo is on thier annual fund raiser

I don't know how they would be able to do this. To my knowledge the only way to tell what size motor it is besides stickers is to get the vin number off the motor and then they would have to research it to find out what the HP really is.

If you can alter a 9.9HP to have 15HP(slightly larger carb is often all it needs)you can alter a 25HP to have 20HP
A dirty air filter is all it takes to reduce HP
Leave the stickers off-let them figure what the horse power is at the prop.
I have never seen a portable dynomometer.
If the law states rated horse power there is not much you can do.
If it only limits HP it is up to them to proove what it is.


Engine serial numbers are not random.
They have manufacturer, date of production, model and HP
It would not take more than 1 page to have all this information

You are correct in that it would take some doing.

The bottom line is be aware that Pa may be clamping down on the HP limit and if you are willing to try an oversized motor on some of these lakes at a cost of $300 plus then that is a personal decision and hopefully , you  get by. However, don't brag at the launch about it.

Marty,
     If your information is correct (and 99% of what you post is) then what they would need is a corresponding list of carb serial #'s to cross reference with the engine #'s.  Also, I heard somewhere that there is some sort of accustic device that can measure H.P. by listening to the engine at W.O.T.  You heard anything about that?  I guess it would stand to reason that a more powerful motor would be louder. I just can't find the pertainent infomation.

This is about all I could find about HP sensers:
http://findarticles.com/p/articles/mi_qa3618/is_199801/ai_n8793054/pg_2

Probably not possible on an outboard motor unless in a lab.
Noise does not increase by HP alone-the only differance between a 305 and 350 engine is bore size but probably the same noise level.
Change the cam and igniton timing and noise will increase dramaticly.
My 454 with comp cam is louder than a stock 454MAG.

I don't think they would be able to check your carb. You can keep a carb off a 9.9 and rejet it to a bigger opening and let more fuel in. Personally I think it would be very hard for them to do. Marty is right to my knowledge of the number containing the horse power. But I have also seen engines that the number was pretty beat up. The only real way they could in force that is if they made you bring your engine in to test it. If you are at the ramp talking about how your engine is a 20 horse with 9.9 stickers on it then I think they might have a case but if you don't say anything it would be up to them to prove your 9.9 is really a 20 horse.
 
Also Marty the HP sensor in the link you posted above looks like it is for machining equipment. Wouldn't do the same thing for a boat motor. I work in Tool and Die and they make those for production shops so they can stop the machine when a tool breaks with out someone watching it all day.

Was up arthur last night and the game comm.  check my motor twice. Once on the way on the water and once on the way off the water. **** JUST A LITTLE MUCH !!!!!!!!!!!!!!! the first officer was nice and the second one was just plain NASTY But I was good to Go.

get a 9.9

Bore it out, put steped pistons in it, raise the compression ratio to something rediculas like 15:1 then rejet the carb and put high octane airplane fuel in it.

I made a honda 200x three wheeler stand up from a slow roll in 3rd gear, cant even imagine what you could do with a two stroke. It was bored out .020 over.... i miss that machine.