yamaha 60 or 70

[cleve]

i recently bought a 2004 yamaha 60 2 stroke. the 60 and 70 are the same motor except the 60 rpm is 4500-5500 and the 70 is 5000-6000. with the prop i have my rpm is @5700. what is the difference in the two motors? is there really a 10 h.p. gain in the 70 or does it just have a higher rpm range? if there is a difference, could i convert mine to a 70 without it costing a fortune?

 

[deejaycee_2000]

Re: yamaha 60 or 70

there is a difference ....

Why don't you just cut your rev limiter and mount your motor higher .....

 

[cleve]

Re: yamaha 60 or 70

the guy i bought it from ran a 17 pitch prop and turned 6000rpm. i have it mounted one hole up, and may go higher. if the two motors are the same how is the 70 making 70 h.p.? i wonder if there is a different computer module or relay, or could it be more complicated than that?

 

[Silvertip]

Re: yamaha 60 or 70

Nope -- all they do is change the decals and charge you several hundred dollars more for the 70. Or do you really have a 70 with 60 decals???? Of course there are differences but the only way you will know for sure what they are is to compare the parts lists for the two engines. Carburetion, porting, exhaust tuners, and ignition timing are all ways to control the output of a two stroke outboard. If you are talking about four stroke engines, its cam, compression, carburetion, exhaust and timing. Every manufacturer has at least two and even three or four HP ratings from what is essentially the same engine block. People look at the displacement (CC or cubic inches) and think the engines are identical. The answer to your question though is yes -- you can make the changes but you will not like the price tag. It is very inexpensive for the manufacturers to make the changes during manufacture since all they need to do is select part "A" from the bin instead of part "B".

 

[cleve]

Re: yamaha 60 or 70

really, they just swap the decals !!? i know there are differences in the two, but what exactly. if anyone out there knows specifically post it for me.

 

[cleve]

Re: yamaha 60 or 70

there has to be someone on this forum who is familiar with these yamahas.

 

[Silvertip]

Re: yamaha 60 or 70

Come on Cleve, nobody is going to do your research for you. The only way you are going to know what the parts differences are in these motors is to compare the parts list. Then when you find that the machined block part numbers are different, you will then need to determine why. The answer will likely be because they are ported differently. That means you would need to have your 60 torn down and ported the same as a 70. And what machine shop, other than a performance oriented shop is going to know that? And are you prepared for to spend the kind of money it takes to do that? You will then likely need three new carbs and perhaps an exhust tuner. You see where this is going? The cost to get 10HP is simply not worth the expense. If you want a 70, buy a 70. If you can find a blown 70 power head you could transfer the intake, carbs and exhaust tuner, then time it using 70 specifications and hope you get your moneys worth. Chances are you will see only a marginal improvement at best.

 

[cleve]

Re: yamaha 60 or 70

silvertip, i understand what you are saying and i have researched it but can't find the specific difference in the two. an old boat mechanic i know told me he thought it was a module but was not sure. there have been several motors through the years that were simple to convert most are not. i had a 30 h.p. tohatsu once. the only difference between it and the 25h.p. was a gasket on the carb that could be removed in 30 minutes. i'm sure the 60 is not that easy, just curious.

 

[deejaycee_2000]

Re: yamaha 60 or 70

that is the difference between yamaha and tohatsu ......