Twin Yamaha F150's. Normal For RPM To Not Be Synched?

[diesel5599]

I got my first boat with outboard engines last weekend. I went from having single I/O's for the last 10yrs or so to getting a boat with dual outboards. My question is, is it normal to have to constantly tweak the throttle handles to get both engines to have the same RPM?

I always thought if you moved both handles simultaneously that some computer somewhere would make sure both motors always had identical RPM's, but on my first trip out, the right motor was consistently up to 3K RPM ahead of the left motor. The fix was to constantly play with the left handle until it matched the RPMs for the right engine, is this normal?

I think I spent more time trying to keep the two synched then I did actually driving the boat. Does it really matter if they are a few thousand RPMs off, am I doing something wrong, or is something wrong with my setup?

Thanks in advance.

 

[Fl_Richard]

Re: Twin Yamaha F150's. Normal For RPM To Not Be Synched?

Afew thousand RPM is alot to be out od sync. A few hundered is acceptable.

You didnt mention the age of your engines. If they are newer they may have an on board computer capable of syncing them. If they are older then tapping the throttles is the only way to do it.

I have twin 95' 150's and the Twinscan fuel management system that shows when the engines are synced, but you need to sync them manually. Once done they will stay within a few hundered RPMs of each other.

Happy boating

 

[diesel5599]

Re: Twin Yamaha F150's. Normal For RPM To Not Be Synched?

They were made in 2007 so about 3yrs old. When the handles are exactly side by side the right engine is about 3000 rpm ahead of the left engine. If I keep tweaking it and either pull the right handle back or push the left handle a good inch or so forward then their RPMs match.

 

[sdsaw]

Re: Twin Yamaha F150's. Normal For RPM To Not Be Synched?

It sounds like you could use a throttle cable adjustment to get the throttles to match closer
There are adjustments on the motor where the cable hooks on

 

[diesel5599]

Re: Twin Yamaha F150's. Normal For RPM To Not Be Synched?

That's what it feels like, I'm just surprised that with all this modern technology there's no 'synch' button I can push.

 

[Fl_Richard]

Re: Twin Yamaha F150's. Normal For RPM To Not Be Synched?

The technology is there you just didnt buy it

 

[Seadoomanls]

Re: Twin Yamaha F150's. Normal For RPM To Not Be Synched?

I gotta ask again...3000 RPM difference or 300?

Let me put it this way. In my bass boat I can idle at 1000 RPM through a canal. If I go to WOT I am at just over 5000 PRM. If I cruise at about 35 MPH my RPM is around 3800, which is less than a 3000 RPM difference from idle.

My point is, if you mean you get a 300 RPM difference, that could use some adjustment (possibly throttle cable) but also isnt a HUGE deal either.

I would think if you were getting a 3000 RPM differnce one motor would be idling (or just above) and one would be at about 4000-4500 RPM which would cause the boat to want to SHARPLY turn opposite of whichever motor it is.

 

[diesel5599]

Re: Twin Yamaha F150's. Normal For RPM To Not Be Synched?

Seadoomanls I think you are onto something. I now can't remember if it was 300 or 3000. Now that I think about it I think it was 300. 3K RPM is a pretty big difference like you said, the boat would practically be going sideways if they were that far off. I'm taking it out this weekend, I'll double check, but now I'm pretty sure it was only 300.

 

[Seadoomanls]

Re: Twin Yamaha F150's. Normal For RPM To Not Be Synched?

I am almost 90 % sure its 300. At which point I would assume is ok. My dual outboard boat never had synced RPM's and it was very managable. 300 rpm never made a ride difference for me.