Help with plug reading please

[danduta]

I have been trying to adjust my carbs on my 787 motor and find this a supreme pain.
I've got high speed needle closed all the way and got the PTO low speed needle at 3/4 and MAG at 1 turn. The ski runs a bit rough below 4000 RPM but runs well above. I rebuilt both carbs and the motor is a fresh rebuilt with maybe less than 2 hours on it. I've only hit 5500 RPM given that I am still breaking it in.
I think the mag side is a bit lean?
Any suggestions,opinions?
Thanks in advance.
Picture 1 and 3 are the PTO plug 2 and 4 MAG

 

[Dr Honda]

If it's a fresh rebuild... then don't try to tune. Just set the carbs per the factory spec, and ride it. The idle will smooth out after the rings seat.

Also... proper break-in requires some full throttle runs !!!!! You need the heat and pressure to seat the rings, and swell the crowns. My rebuilds see full throttle within minutes of getting on the water. If you baby it... it will never make peak power. I'm not saying to hold it wide open for miles... or abuse the engine... but it needs to be rev'ed up.


Lastly... a fresh rebuild runs hotter (internal) than an engine with some time on it. So, reading the plugs is hard, as they tend to be light for a while. You need to read the wash on the piston crowns. To do that... you need to either remove the head, or use a bore scope.

 

[danduta]

Thank you Dr Honda.
Can I leave the air box off while I do the adjustments?
Or should I run it with the box on?

 

[pwgsx]

Leave it on or you will be having more air flow and run lean.

 

[mikidymac]

Never run it with the air filter off. Set the low speed screws back to the factory spec and they should both be the same.

 

[danduta]

I will reassemble the whole show and run it for a few days.
I have set both screws at 1 1/8 or should I run it a little richer as the motor breaks in? The manual says 1 turn +/- 1/4 turn