2003 Nissan 9.8 2 stroke whine/chrip

I run a 2003 Nissan 9.8 2 stroke (NS98B) on a 14 Sea Nymph. The motor runs great but every time I throttle her up there is a whining sound coming from somewhere in the motor. It happens at around 1000 - 2000 rpms when i throttle her up to plane and when i bring her back down off plane. It is NOT there at idle speed or top 2/3's speed. It does it no matter how the boat is loaded. It's been occurring all season. I took her out for probably the last trip of the season this past Saturday and tried to video it but the audio is not great. Around the 45 second mark is the best example of the sound but it's a little louder in person. Would any of you guys have a suggestion on what/where the whine is coming from? Is it something i should be concerned with? The motor probably has a dozen trips on her with the noise. Thanks!

https://www.youtube.com/watch?v=WqJavv3cg18

Huh ... I got zero sound from your YouTube post ...

I hear it,not sure what it is though. Almost sounds like carb pulling in air if that makes any sense.

I apologize for horrible the audio quality. If it was a carb pulling air, would it do it only under a load when in gear? Everything sounds normal when revving in neutral. I haven't tried it in reverse.

Thanks for the response!

I hear nuting!! As Sergeant schultz would say. Audio was there but no whine to my hearing.
Tim

did you hear that whine before or after you ran that cable for the tach ? If after it might be a carb noise, like a 4 bbl on a big block w/no breather. If I'm making any sense .............

Charger25 said:

did you hear that whine before or after you ran that cable for the tach ? If after it might be a carb noise, like a 4 bbl on a big block w/no breather. If I'm making any sense .............

Click to expand...

I don't remember. I put the tach on so i could determine the best pitch for a replacement prop. It's one of those simple "wrap around plug cable" types.
If the carb was pulling air, would it do it only under a load in gear or would it also do it revving in neutral?

not sure, that 15 I got whines alot like that also. never figured it out,but it runs well. sooooo I'll run her till she blows and I have run it hard.

My outboard manual and personal experience says trailing throttle chirp/whine/rattle is or could be rod big end play.

I run this little 9.8 pretty hard also. Since i put a higher pitch prop on her she runs WOT at about 6100 RPM's when i'm solo. She's rated at 5000-6000 so i try to be mindful keeping under 6000. With 2 guys on the boat its not a problem.

Would a rod or a bearing make that noise while revving in Neutral or only under a load while in gear?

Thanks!

FWIW I once had a big V6 where there was an issue with one of the 6 carb gaskets (looked like a little rubber bowl) and she made a howling/wind/whistle sound above 3500 RPMs. A few local Dealers said "Don't worry about it", since it ran so well.

Finally took it to an old OMC guy and immediately upon hearing it he knew instantly that is was caused by air being sucked in. **** those old timers don't need any books!