Question about cavitation and max rpm

[zackmorris]

2006 sx230 HO

Just replaced plugs

Filter is fine. No oil saturation.
Checked throttle position at full throttle on both engines and both are at max position- I can’t force the throttle any further on either engine


the starboard engine is only hitting 9.8k rpm when running and wide open. The port engine hits 10.2k.
If I floor it from a stop, both engines will hit 10.2k during cavitation- but the starboard will settle down to 9.8k once it catches. Port will settle in and remain at 10.2k.

they seem to idle fine- no issues with a miss or anything.

outside of coils, what else should I check?

Is the cavitation when going full throttle from a hole shot normal? When do the impellers and related bits need to be swapped?

 

[Acard7]

Check oil level just to make sure it’s within normal limits. Obviously if your air filters are fine you’re not overfilled.. When checking your throttles, they were all the way against the throttle stop?.. Or are you just talking about the throttles themselves or the actual throttle stop? Inspect your impellers to see if they are chewed up, if they aren’t then you shouldn’t really need to change them. Re-greasing the cones wouldn’t be a bad idea but I doubt that has much to do with it.

 

[Quad]

Which years of boats had varied pitch on the impellers?

 

[Cobra Jet Steering LLC]

2006 sx230 HO

Just replaced plugs

Filter is fine. No oil saturation.
Checked throttle position at full throttle on both engines and both are at max position- I can’t force the throttle any further on either engine


the starboard engine is only hitting 9.8k rpm when running and wide open. The port engine hits 10.2k.
If I floor it from a stop, both engines will hit 10.2k during cavitation- but the starboard will settle down to 9.8k once it catches. Port will settle in and remain at 10.2k.

they seem to idle fine- no issues with a miss or anything.

outside of coils, what else should I check?

Is the cavitation when going full throttle from a hole shot normal? When do the impellers and related bits need to be swapped?

A boat of that year having top r p m's of a small variation is not a problem what is the issue you are experiencing aside from just a small variation at top end r p m, I mean if it runs good leave it alone. and by now if the impellers and pump liners are original it is probably time to measure the clearance between the impeller and liner and look at the condition of both.

 

[David Martin]

Your gauges could be off a little...............boat hull leans to one side due to uneven load will cause the intakes to be a little different........back pressure on the exhaust could be a little different..............cable movement due to a loose cable tie down .....man the list could get long,...... your are so close I'm not sure there is to much wrong. Instead of trying to gain such a small gain on the 9.8 to 10.2 just take the 10.2 down...... even that would difficult on such a small amount of adjustment on the throttle stop. Just a thought

 

[Cobra Jet Steering LLC]

One other point of interest is the fact that because the twin engine setup is NOT counter rotating Yamaha used 2 different pitched props to accommodate for this and then they just stopped that practice so if the boat is running good just forget about it and go have fun while the sun shines.