2019 GP1800 very loud and slight power loss

[Scorn1800]

I have a 19 gp1800r with 90 hrs on it. Put it away at end of last season and it ran fine.
Put it in water this year and it seemed like slight miss and very slight power loss, was very choppy out and rode ski around to my lagoon.
Once in lagoon ski got loud and rpms were jumping slightly and more of power loss. Got it to my jetdock and removed seat.
Ran it on hose and it loud but can't see any exhaust smoke coming from anywhere. I removed all plastic exhaust hoses and tubing and checked for cracks.
Everything checked out ok. ran it again and it sounds exhaust related. It starts and runs every time. Could a baffle broken away inside water box? I plan to bring it to dealer this weekend as I'm at a loss of what it could be. Any ideas?

[K447]

The loudness might be the exhaust parts contacting the inside of the upper deck. Check for clearances behind and around the exhaust plastics and rubber.

Also check under the resonators, see whether they might be banging against the supports

power loss may just be a need for fresh spark plugs.

how are you measuring this power loss?

[Green Hulk]

I have a 19 gp1800r with 90 hrs on it. Put it away at end of last season and it ran fine.
Put it in water this year and it seemed like slight miss and very slight power loss, was very choppy out and rode ski around to my lagoon.
Once in lagoon ski got loud and rpms were jumping slightly and more of power loss. Got it to my jetdock and removed seat.
Ran it on hose and it loud but can't see any exhaust smoke coming from anywhere. I removed all plastic exhaust hoses and tubing and checked for cracks.
Everything checked out ok. ran it again and it sounds exhaust related. It starts and runs every time. Could a baffle broken away inside water box? I plan to bring it to dealer this weekend as I'm at a loss of what it could be. Any ideas?

Change your spark plugs. They go bad after sitting up for a long period of time. They should be changed before the first ride every season.
I know you checked your exhaust, but check it more carefully. The stock plastic and rubber exhaust components are crap and prone to popping loose causing an exhaust leak into the hull which will also cause power loss. I highly recommend the Riva rear exhaust.

[kmaher]

+1 for spark plugs....are you sure that they're all torqued down properly and the boots are fully seated? My first thought is you aren't firing on all cylinders, which would explain the "louder" sound and power loss.

What exactly do you mean by power loss, too? Just acceleration, or were you seeing slower speeds too? If slower speeds, what were you reaching?

[johnhoo08]

+2 for spark plugs. It's amazing how much these Yamaha engines eat some plugs. Very reliable after a new spark though!

[Scorn1800]

Just want to thank everyone for the hep on this. I installed new plugs last friday morning and ski sounded how it should. Took it for a ride friday afternoon and it ran perfect. Put another 3 hrs on ski over the weekend and it ran great.

[Green Hulk]

Just want to thank everyone for the hep on this. I installed new plugs last friday morning and ski sounded how it should. Took it for a ride friday afternoon and it ran perfect. Put another 3 hrs on ski over the weekend and it ran great.

Happy to hear that!