8 hp. Yamaha

[GasCan II]

I have a 8 hp. two cycle Yamaha , the # on it are 8SF , 661-S- 038228. It is getting a slight amount of water in the lower cyl.
Where should I start looking for the problem ?
Thanks !

 

[jerryjerry05]

Re: 8 hp. Yamaha

Start with a comp test.
Then pull the head and check the gasket and head for cracks.
Hope it's the gasket.

 

[GasCan II]

Re: 8 hp. Yamaha

JerryJerry05;
Thanks for the reply. I'm going to check it out and I will post results.
Thanks again !

 

[GasCan II]

Re: 8 hp. Yamaha

O.K. now I did compression test and got 125Psi. in both cylinders, and they both will hold the pressure without bleeding down for better than 30 min.
Now where do I look ?

 

[GasCan II]

Re: 8 hp. Yamaha

O.K. now I did compression test and got 125Psi. in both cylinders, and they both will hold the pressure without bleeding down for better than 30 min.
Now where do I look ?

How can water get into cyl if it holds good comp. ?
Could it be from contaminated gas ?

 

[GasCan II]

Re: 8 hp. Yamaha

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[99yam40]

Re: 8 hp. Yamaha

O.K. now I did compression test and got 125Psi. in both cylinders, and they both will hold the pressure without bleeding down for better than 30 min.
Now where do I look ?

If you are using a compression tester with a valve in it, that valve is what holds the reading in the gauge not the cylinder

Leak down tester is a whole different set up and that shows how much leaks out of cylinder and where if you know how

 

[GasCan II]

Re: 8 hp. Yamaha

Thanks 99am40;
Did't realize that.
Can't figure out why this motor froze up. I had to put penettraing oil in it to get it to turn over, than everything seems fine.I ran it for an hour on the hose. Could not enough oil in the oil cause this ??
Thanks

 

[99yam40]

Re: 8 hp. Yamaha

Thanks 99am40;
Did't realize that.
Can't figure out why this motor froze up. I had to put penettraing oil in it to get it to turn over, than everything seems fine.I ran it for an hour on the hose. Could not enough oil in the oil cause this ??
Thanks

Not enough oil in fuel will usually cause bearing problems before cylinder /piston problems, but lean fuel/air mix or overheat will get piston too hot and cause cylinder/piston damage. But you started out talking about water in cylinder. Take apart and see what you find. rust or scored piston/cylinder