1999 Yamaha 25 hp 4-stroke

[rick_l]

I recently purchased a yamaha 25hp 4 stroke motor. The motor has a noise in it and i was told that a 4-stroke should be quiet. My question is could it be the rod bearings. Someone told me that these motors had problems with the rod bearings.

 

[rodbolt]

Re: 1999 Yamaha 25 hp 4-stroke

never had an issure with rod bearings.
that motor was a merc design, 2 cylinders with 3 pistons.
the 3rd piston was a balancer nd tended to make noise.
without hearing the noise its hard to say.
does the noise change when you kill a cylinder ?

 

[gotboostedvr6]

Re: 1999 Yamaha 25 hp 4-stroke

my 25 makes noise aswell. not to mention it vibrates you to death

 

[hanolfe]

Re: 1999 Yamaha 25 hp 4-stroke

I have a yamaha 25hp four stroke outboard also and I hear a strange knocking noise from it. I suppose that the source of noise is the harmonic balancer. I was told by the dealer that I need to replace it.

 

[gotboostedvr6]

Re: 1999 Yamaha 25 hp 4-stroke

? how much

 

[hanolfe]

Re: 1999 Yamaha 25 hp 4-stroke

too much... in our contry it is ~$500-600.

 

[gotboostedvr6]

Re: 1999 Yamaha 25 hp 4-stroke

did you happen to have a part number?