Sync not working at times

[Aln2202]

Im running twin 2015 300ap with electric shift. This weekend I noticed my motors would not sync when running and I could actuallly hear a difference with the way they sounded when running. But a few time on restarts they would sync fine.

any idea on what to look for.

also still trying to get the WOT rpm and speed up where it should be and wondering if it is something with the motors and how I can check them.

the port motor is at least 300 rpm less then starboard motor at full throttle. Wot rpm is only 5100 on starboard.

very frustrating to say the least.

motors only have 260 hours all maintenance has been done.

thanks

[Moonlighter]

Firstly, you are either over-propped, or the engines are set too deep. Or both.

You are currently not doing your engines any favours at all by lugging them set up so they max out at 5100rpm.

You need to set those engines up so they will pull 6000rpm at WOT. No iff’s, buts or maybe’s. That is the target.

Get that right and then see if you still have an issue.

One further thing - once you have the engine height right and correct props to get that 6000rpm, get the props scanned and tuned so they are identical. It is not at all uncommon to find brand new props that are supposed to be the same size to vary by up to 1” in pitch and to have significant imbalances. A professional prop shop will be able to balance them and match them upperfectly and this greatly helps when it comes time to sync twins.

[Aln2202]

Thank you for quick reply. When I first installed the motors I had the motors mounted one hole higher then the lowest setting and the boat would not have a good hole shot and would lose bite no matter what props I tried . 3x21.5,3x22, 4blade etc.

i lowered the motors all the way down and went back to the 3x21.5 and bite was ok but just can't seem to get the WOT where it needs to be and I'm concerned about doing any damage to the motors like you said.
The boat has a stepped transom.

[Moonlighter]

Well, the problem is most likely still because the height and or prop combination is not right, assuming that the engines are running fine and no codes on the SDS.

The DF300’s typically run 16” diameter props, you dont say what yours are.

In any case, you need to address the lugging and one way or another, get those WOT revs up to 6000. You will get better hole shot and fuel economy.

Leaving it like it is will shorten its life due to the excessive lugging it is doing now.

Maybe it is time to take it to an experienced Suzuki dealer and ask them for advice and assistance?

I hear lots of stories from the US that the larger Suzuki’s “need to be buried deep”. Funny though we dont have the same issues here in the land downunder....

[Aln2202]

Moonlighted, thanks again for the reply.i hear you about what everyone says about needing to bury the Suzuki motors, it goes against alll I've read about motor performance. Makes no sense.

but what confuses me also is when I had the old motors which were 300 HPDI Yamaha they were mounted from the factory all the way down too and my performance was what I posted. So that's why I went back down to the lowest hole.

If I raise the motors up where they look like they should run and I have trouble with cavitation then which way do I go with prop size and pitch?

and yes all the props were 16" diameter Suzuki brand. Except one set of 4 blades that Suzuki makes in I believe 15.75 diameter. I've lost track of what was put on the motors.

trying to find a decent Suzuki shop is a crap shoot.