Repower ?

canoemang

Petty Officer 1st Class
Joined
Apr 9, 2011
Messages
350
So i am going to be getting rid of my 1986 Merc Tower of Power 115 jet this winter and repowering with a Yamaha 150 and converting it to a jet foot from outboardjets.com.

I am currently looking at a late 80's - mid 90's V6 150's Yamaha's and I'm wondering what i should be looking out for as far as common problems etc..

what are good compression numbers for these motors and what are some of the more reliable years.

Thanx in advance guys!!
 

Charlie in TX

Petty Officer 3rd Class
Joined
Jun 18, 2009
Messages
98
Re: Repower ?

Well you didn't ask about a specific motor. You will have to do some reaserch to find the compression ratio of the engine. Multiply that by 15 then by 0.9 for about the most you can expect. As important, all readings are within 10% of each other. As an example, I have 150 HPDI. They have a 6.6 compression ratio (if I recall). 15*6.6=99. 90 is about ideal.
 

canoemang

Petty Officer 1st Class
Joined
Apr 9, 2011
Messages
350
Re: Repower ?

I did not ask about 1 specific year/make or model.

I did however ask about some of the more reliable years and compression. I know all outboards are only as dependable as the PO in reality, but i also know some have better years than others and since i am buying i have a choice.. say if the mid to late 80's are junk ill stay away from them.. etc..

Thank you for the equation for compression.
 
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