2010 Nitro Z 8 not getting over 52 mph

[Upland A5]

OK,
I got to try a couple props on my boat. Here is what I have come up with in findings. Got better with the 23 but still have about 300 rpm before red line. Any advise at this point?
Prop #1 tempest pitch 25
5400 RPM max
55-57 MPH
Water broke at driver’s seat
No more than 1/2 trim

Prop #2 Fury 23 pitch
5600 RPM max
62 MPH
Water Broke 3 ish feet from back of boat
5/8 trim

I have a 2011 Z8 with 200hp pro XS. I purchased it about a year ago and have experienced a loss of RPMs at WOT. I have 3 different props I’ve tried at multiple prop to pad heights. 21 tempest, 23 Yamaha pro series and the prop the boat came out new with 24 furry. I’ll start a new thread with the results of my experiments of these props but I will say that the 24 furry still doesn’t produce the mfg’s recommended rpm range of 5500 to 5750 @ WOT. I wanted to let you know that I had at least 2 different things going on that improved the loss of rpm’s. First thing I found was a loose connection of a fuel line inside the big tube from the transom to the motor. The previous owner had at some time replaced the fuel bulb and had spliced the fuel line inside that big tube. What I found was the splice connections weren’t tight and I assume it was sucking air at its state of WOT when it calls for the most fuel demand. That alone raised the rpm’s from 5100 to 5300 @ WOT. That was late last fall and I thought my troubles were solved until this spring and the rpm’s declined to almost the exact #’s, 5000-5100. So fast forward and the cause wound up being a failed exhaust plate gasket or also called an adapter plate gasket. The one on top of the plate. According to the Mercury tech that I was able to bounce things off of he told me there is something called a tuner in the midsection that was getting wet when it shouldn’t have been. This brought the rpm’s back to around 5300. I still think there maybe an issue because I feel the boat should produce closer to the mfg’s rpm range of 5500 to 5700. I bit the bullet and currently have the boat at a local shop and they are going to take the boat to the lake and run it with a computer. Maybe I’ll no more soon but thought the information may help you.

[Red Beard Ryan]

I have a 2011 Z8 with 200hp pro XS. I purchased it about a year ago and have experienced a loss of RPMs at WOT. I have 3 different props I’ve tried at multiple prop to pad heights. 21 tempest, 23 Yamaha pro series and the prop the boat came out new with 24 furry. I’ll start a new thread with the results of my experiments of these props but I will say that the 24 furry still doesn’t produce the mfg’s recommended rpm range of 5500 to 5750 @ WOT. I wanted to let you know that I had at least 2 different things going on that improved the loss of rpm’s. First thing I found was a loose connection of a fuel line inside the big tube from the transom to the motor. The previous owner had at some time replaced the fuel bulb and had spliced the fuel line inside that big tube. What I found was the splice connections weren’t tight and I assume it was sucking air at its state of WOT when it calls for the most fuel demand. That alone raised the rpm’s from 5100 to 5300 @ WOT. That was late last fall and I thought my troubles were solved until this spring and the rpm’s declined to almost the exact #’s, 5000-5100. So fast forward and the cause wound up being a failed exhaust plate gasket or also called an adapter plate gasket. The one on top of the plate. According to the Mercury tech that I was able to bounce things off of he told me there is something called a tuner in the midsection that was getting wet when it shouldn’t have been. This brought the rpm’s back to around 5300. I still think there maybe an issue because I feel the boat should produce closer to the mfg’s rpm range of 5500 to 5700. I bit the bullet and currently have the boat at a local shop and they are going to take the boat to the lake and run it with a computer. Maybe I’ll no more soon but thought the information may help you.

Thank you for the info. Please keep me posted.

[Red Beard Ryan]

PTP is 4 inch

[DucksnBobs]

Just another thought. I have a 2008 opti 150 on a z7. One day i might be cool enough to put a 200 on it. With that said, motor checked out and never through any kind of code. I even took it to a dealer and received like a 14 page printout from when the dealer put his computer on it to show any faults. All came back clean, yet the dang motor wouldn't break like 5k RPM (if memory serves, 4800 was the absolute max). Even trying different props... nothing changed. Come to find out, and I really have no idea how true this is, but it seems true for me, that these optis will run on a faulty cylinder and not go into guardian mode. I changed my plugs and instantly gained about 800 rpm. Changing plugs, once a year or every other year, really keeps these older optis alive and well.

Z7, 150 opti, HIGH ELEVATION and still able to run down the lake at 50-54 mph, with half of cabelas in my boat. At sea level I am touching 60 with just me in the boat and same load with a much high pitch prop. With a 200, these little z7's are a different animal. Good luck on figuring out your boat, its never a fun process. Seems you're getting there with trying different pitch props, but don't settle and make sure you kind of go through everything.

[BMCD]

i would suggest changing plugs, fuel filter and water strainer. when u change the fuel filter look for debris in the cylinder. start here first.