Last Spring I purchased a 08 Skeeteer ZX200 with a 200 HPDI from a local dealer. Boat was pristine and outboard only had 420 hours on it. I only got the boat out a handful of times last year and noticed that the top speed was around 50 mph using GPS. After researching this I found out this was pretty far off of what it should be. I changed all the fuel filters, spark plugs, and ran ring free in the fuel. I only use non ethanol fuel. With no improvement I took the boat to dealership to have them investigate the issue. Turns out the drive shaft bearing is toast. Since it was like that when I bought it the dealer is helping me out with replacing the foot with a new one. I wrote all that to say this. I searched every forum I could for probable causes of low top end and nobody suggested a bad driveshaft bearing. I was lucky that it didn't completely fail while running and I want to share this so that if anyone else is having a similar issue and have done all the easy things to try and remedy the issues with no success, this could be your issue too. Don't just roll with it and not have it looked at.

 

Good info!  Thanks for sharing.  Did your dealer have any idea what caused it?

@Glenn No they didn't have an idea of what caused it. My opinion is that with not that many hours on it for an 08, sometimes not using something enough is just as bad as using it too much.

Sometimes you just never know what will fail and how it will affect your performance.  I have the same motor except a 250 and while doing regular maintenance found a white plastic piece in the bottom of my cowl.  Come to find out it was the clip that holds a bar from the throttle to tell the oil injection system how much oil to send to the cylinders.  The bar was hanging loose.  Luckily when that happened, it is designed to fail in the full oil position.  Otherwise, I would have oil starved my 2 stroke and most likely locked it up.  

@TOXIC The last gen 2 strokes definitely have a lot more going on with them.  I grew up fishing on a Procraft 17 combo fish and ski with one of last Mercury Force 120 motors. Such a simple motor and it is still going to this day. No issues. It must have 4000 hours on it. I know people give those motors a lot of crap, but the Mercury ones were not as bad. The one I grew up with has a black max foot. It also has Mercury carbs, Ignition, and Power Tilt and Trim . Runs like a top. It has lost a little compression over the years but it's not terrible. New it would push the boat 53 mph with 3 people on it and with as many hours that is has on it, it will still push it with 3 people on board 45 mph.  Mercury replaced all of the bad stuff from the Bayliner days. About the time they go it right, the emission regulations killed it. 

 

That’s probably one of those 1:10,000 failures so you would probably never find someone that has ever even heard of it.  Hopefully it was discovered before it caused some serious colateral damage.

Wanted to provide an additional update. After replacing the lower unit about 300 RPMS were restored but still not right. One of the fuel injectors was stuck closed. Hopefully after the new injector is installed I'll have proper RPMs. Fingers crossed. Everything else has checked good including the high pressure fuel pump and good compression.