Yamaha 90hp compression

[brewmister]

I am looking at a 93' 90 hp yammie and the compression is only 98 to 104 across the 3 clyinders.
Could someone tell me what I am in for if I buy this motor?

And what it would take to fix it so I would have a normal reliable running engine with normal compression.

 

[rodbolt]

Re: Yamaha 90hp compression

have a cylinder leakdown test done, much more accurate than a compression test.
your numbers seem ok. its normal on a 3cyl yamaha to read progressivly lower numbers on the middle and bottom cylinders.
have the gearcase carefully inspected as well.

 

[brewmister]

Re: Yamaha 90hp compression

Thanks for that quick reply. Just one more question......he said it has sat f or 5 years without beeing started.
what kind of impact willl taht bring.

 

[JB]

Re: Yamaha 90hp compression

It will certainly need an impeller and probably carbs overhauled.

 

[brewmister]

Re: Yamaha 90hp compression

thanks again...

I wanted to make sure for sitting it wont have any bad impact on the performance.