yamaha ob question

[mississipi]

I have a 06 Yamaha 115 4-stroke. it has started making a weird noise that I cannot figure out and I am wondering if anyone might have experienced something similar. the noise  occurs at 1000 to 1200 rpm in gear only. slow down or speed up and the noise stops. the noise is similar to the noise that comes from blowing across a glass soft drink top but is higher pitched and is like woop woop woops in rapid sucession.  I have taken the cover off and ran it and it dosnt seem to be any louder. if you trim up some it quietens it down but is still there. I have had the motor since new. the only change I have made is changing from a ss 3 blade prop to an aluminum 4 blade prop. the noise dosnt really sound like metal friction as a bearing or something but it could be. aside from the noise the motor performs perfectly as it always has       Thanks   Any help would be appreciated

[johnr]

I think catsnstripers had a 115 that made the same noise occasionally. I remember it making some type of lower rpm noise, I just can't remember what exactly it sounded like .

Maybe he will see this and remember.

[drag4striper]

Not sure if it's your problem. They(yamaha) have had noises like a belt squealing after the engine gets warm and you only hear it at low speeds . The engine running will hide the 

 noise at faster rpm's. If that is what your hearing, I read it is a dry rubber bushing with the metal drive shaft running through it. Lots of info online. Temp. fix 

you can spray lube on the shaft from the outside but it will wear off. Whenever you have a water pump installed the bushing and shaft can be lubed with yama-lube grease and will last a while.

As I understand it's the nature of the beast. If this is not your problem look under I boats site or the other boating sites may help you.. 

I have an 2009 yam f115 and it does this same thing.

[mississipi]

Thanks for the responses. I was able to find some info online, seems its a fairly common thing. I will drop the lower unit, grease and see what happens.

[drag4striper]

I've also read that Yamaha offers a replacement bushing that has a little larger inside diameter to combat this noise.

 If you are going to drop the lower unit you might want to check with a dealer to see if they do offer it.