Engines have diferent RPMs

[Michael Guzzo]

Hi all! Just joined the forum as I am in the process of purchasing a 2012 242 limited S. Had the water test today and something struck me as odd. The 2 RPM gauges were off from each other in the range of 200-400 RPMs. I pointed it out to the sales rep and he said that it was normal. He then went on to say that they would never be exact because the boat had two different sized impellars. Can anyone confirm this to be true? Do I have nothing to worry about? Other than that the boat seemed to run like a dream and was a ton of fun!

Thanks in advance and I look forward to learning a ton from and hopefully one day contributing to this forum.

 

[Julian]

He is correct...the engines will never be in exact sync and the impellers are different pitches due to the way water is pulled into the intakes.

 

[Michael Guzzo]

Great! And thank you for the response. Gives me some good peace of mind.

 

[buckbuck]

@Michael Guzzo we are here to help with all your questions so feel free to do so. Have fun with your buying adventure.

 

[Gym]

Great! And thank you for the response. Gives me some good peace of mind.

If this difference is constant throughout the power range it may be as simple as a throttle cable adjustment which is a pretty simple user adjustment.

 

[tdonoughue]

Yes, and if it gets more than that out of sync, you can adjust, as well. Here is the thread:

https://jetboaters.net/threads/jetb...oat-throttle-sync-cable-adjustment-video.361/

 

[Sotally Tober]

@Michael Guzzo we are here to help with all your questions so feel free to do so. Have fun with your buying adventure.

I'm here if you need to turn your boat into a club....just sayn

 

[Bruce]

Not relevant to this post but the 2015+ 240 series use matching impellers of the same pitch.

 

[swatski]

Not relevant to this post but the 2015+ 240 series use matching impellers of the same pitch.

I know... Must be the keel/rudder effect that makes pitch compensation unnecessary? But there are reports of uneven RPM with faster spinning port, so Whiskey Tango Foxtrot...?

 

[Michael Guzzo]

Thanks again everyone! I think I'm going to pull the trigger and should have my boat on Friday. 1st trip will be heading out of Crystal River and about a mile out in the gulf to go snorkeling for scallops.

 

[Roof]

So, mine seem to be about 200 off at full throttle. I've read that up to 500 is acceptable but I can hear/feel a difference.
Should I wrestle with them about an inch apart(ruins the experience) or just let one run a little faster, or attempt a fix for 200 rpm?
Port is running 7700ish and starboard is 7500ish.
Just got the boat so I'm stressed to touch things im not familiar with (I hit things with hammers).

 

[Dean P]

So, mine seem to be about 200 off at full throttle. I've read that up to 500 is acceptable but I can hear/feel a difference.
Should I wrestle with them about an inch apart(ruins the experience) or just let one run a little faster, or attempt a fix for 200 rpm?
Port is running 7700ish and starboard is 7500ish.
Just got the boat so I'm stressed to touch things im not familiar with (I hit things with hammers).

Hi and welcome to the forum . You should update your boat model and length as the 19' is a single engine boat. Twins typically start at 21' and up.

Even though my boat is a Chaparral, the engines, on plane, even out to well within 200 rpms, at idle I've seen as much as 500. I believe you have a sync button? Not sure, but what you're describing sounds a little outside normal. Hopefully others will chime in.

 

[Roof]

Yes sir, i almost bought the 195 but decided on the 212 due to a the "buy your second boat first" comments.
I didn't get a manual and i have not seen a sync button but my wife says im blind so ill look further

 

[haknslash]

Sync is only for 24' e-series boats that use drive by wire binnacle.

 

[Dean P]

Yes sir, i almost bought the 195 but decided on the 212 due to a the "buy your second boat first" comments.
I didn't get a manual and i have not seen a sync button but my wife says im blind so ill look further

Good for you! If I would have done that I would have purchased that boat too. Funny how things work out.

I believe there's a device/package you can purchase to help sync??? Others have done this so they need to confirm.

 

[swatski]

So, mine seem to be about 200 off at full throttle. I've read that up to 500 is acceptable but I can hear/feel a difference.
Should I wrestle with them about an inch apart(ruins the experience) or just let one run a little faster, or attempt a fix for 200 rpm?
Port is running 7700ish and starboard is 7500ish.
Just got the boat so I'm stressed to touch things im not familiar with (I hit things with hammers).

That sounds about right, the new 1.8 models have identical pitch impellers which is not ideal but okay. Because the STBD side loads a bit more efficiently due to the direction of impellers’ rotation it lowers the RPM on top, 200 sounds about right.

if it drives you nuts, you have two options:

1. tweak the pitch on the trailing edge, probably just one of the two - 7,700 in cold weather will be less in summer heat, so perhaps de-pitching the STBD side - there are threads on how to do that.

2. BETTER option IMO - purchase @Ridesteady and don’t look back! Twins humming along in perfect harmony at any RPM level.

 

[haknslash]

Good for you! If I would have done that I would have purchased that boat too. Funny how things work out.

I believe there's a device/package you can purchase to help sync??? Others have done this so they need to confirm.

The throttle sync just latches the seperate binnacles together to move as one. That doesn't do anything for the different RPM's it just makes operating the seperate levers easier to move as one.

 

[swatski]

Well, yes, there is the throttle sync $150 plastic POS... I hope that’s not what we are taking about, lol

The RideSteady is the BOMB.

—

 

[haknslash]

I never had RS but if anyone wanted to do watersports on a Yamaha or fine tune their RPM's to whatever they wanted it would be a no-brainer mod to have. Better than fooling around with impellers IMHO.

 

[Dean P]

Well, yes, there is the throttle sync $150 plastic POS... I hope that’s not what we are taking about, lol

The RideSteady is the BOMB.

—

Yes I was referring to the RideSteady. Couldn't think of the name. Thx!