New to jet boats! Have some questions

[Jet Boat Junkee]

Hey y’all!
I recently purchased a 2021 Yamaha 255FSH with 15 hours on it thought it would be a great buy as I like this color compared to the newer models. We’ve had a few trips on the water and This boat is a blast!
I did have an issue pop up today where the starboard engine is not revving past 5500 RPMs as well as during idle it’s shaking as if a motor mount is broken. (See attached) when we use the door throttle and just use the port side it almost sounds like a raspy rattle from underneath the helm . The portside engine runs just fine. Has anybody else run into this or do you have any insight? I’m trying to attach a video. I don’t know if it will load or not of the engine shaking.

 

[drewkaree]

Sounds like typical cavitation from weeds or debris

 

[FSH 210 Sport]

5500 rpm is the classic tell tale of a broken super charger clutch.

Pull the intake to the super charger and see if the turbine wheel will spin both directions. If it does the super charger clutch is broken.

 

[Jet Boat Junkee]

I

Sounds like typical cavitation from weeds or debris

I checked the cleanout ports, clean with no debris. Is there any other areas you would check?

 

[Jet Boat Junkee]

5500 rpm is the classic tell tale of a broken super charger clutch.

Pull the intake to the super charger and see if the turbine wheel will spin both directions. If it does the super charger clutch is broken.

Is it pretty common for them to go at 15 hours? I’ll give this a check and see what I find. Thank you.

 

[FSH 210 Sport]

Is it pretty common for them to go at 15 hours? I’ll give this a check and see what I find. Thank you.

It’s not the hours ….If you catch some air off of a wave and the engines rev up then get suddenly loaded again when the boat gets back into contact with the water that does it. The 5500 rpm thing is common when the sprague clutch fails.

There are a couple of companies that make pop off valves to help prevent this.

 

[Jet Boat Junkee]

It’s not the hours ….If you catch some air off of a wave and the engines rev up then get suddenly loaded again when the boat gets back into contact with the water that does it. The 5500 rpm thing is common when the sprague clutch fails.

There are a couple of companies that make pop off valves to help prevent this.

Makes sense, started off great then went for WOT to show off to a buddy and felt the slipping as we were reaching top speed. Do you know the names of the companies that make that valve?

 

[FSH 210 Sport]

Makes sense, started off great then went for WOT to show off to a buddy and felt the slipping as we were reaching top speed. Do you know the names of the companies that make that valve?

A little background…. Did it work correctly when you first got the boat?

 

[Jet Boat Junkee]

A little background…. Did it work correctly when you first got the boat?

Yes, worked great for about an hours worth of use. Then this started today

 

[FSH 210 Sport]

Look here

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Post in thread 'Super Charger clutch fail?'

Sep 29, 2024

I did, I ordered a BOV kit from MacsBoost.com.

MACSBOOST BOV kit

I ordered the new clutch from PWCparts.com and the description says its OEM but it’s an upgraded clutch for 2014 and up SVHO. Not sure when the upgrade would’ve happened, as my boat is a 2017. And from the looks of the oil pump housing and bolts it’s never been apart. So with 310 hours and 7 years old I’ll call that a win no matter what!

SC Clutch kit

I watched a video on YouTube that discussed needing to prime the oil pump / Supercharger. There’s a small bolt to remove on top of the gear side of the SC...

• ldefoggi

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[FSH 210 Sport]

Yes, worked great for about an hours worth of use. Then this started today

Okay check the the turbine wheel first.

If you do a search for super charger clutch fail or blow off valve you’ll get threads dealing with this.

Sorry you are having issues .., I know it’s a rocket.

 

[Jet Boat Junkee]

Thank you, sir! Is this something a moderately mechanical mind can tackle on their own or do you recommend just coughing up the money and sending it to the specialist?

 

[BumbleBee255]

It’s not the hours ….If you catch some air off of a wave and the engines rev up then get suddenly loaded again when the boat gets back into contact with the water that does it. The 5500 rpm thing is common when the sprague clutch fails.

There are a couple of companies that make pop off valves to help prevent this.

Do the super charged jet skis have pop-off valves from the factory? I see and hear them coming out of the water full throttle all the time with no issues.

 

[FSH 210 Sport]

Thank you, sir! Is this something a moderately mechanical mind can tackle on their own or do you recommend just coughing up the money and sending it to the specialist?

For sure you’d need a service manual. Hard to say whether or not you can fix this… might want to take it to the dealer IF you determine that the turbine will spin both ways.

What is this slipping you’re talking about as you reached top speed?

Did you catch any air over a wave at full throttle and land without chopping the throttle?