Yamaha 60 c

[LittleCharger]

You do not want a cleaver prop. Stay with a round ear that will carry the bow weight.

Hydromotive Engineering

Sound advice from one of the best in the prop business

[oledawg]

Thanks Paul. See ya' soon.

[yammi]

60 enduro gear ratio is 2.33 and Yamaha 70 was 1.7? ...who's the best for top speed ? I'm suppose is the 60 enduro because i can put more pitch on the propelers .... Im in the good direction guy's ???

[Roflhat]

You're better off with the 70 'box if you can find one, the 1.71 ratio only came on the CES and the 60D motors, quite rare nowadays. The gearboxes take 13 spline props but are short shaft. The yam/mariner 55 ran a 1.84 ratio gearbox with 13 spline as well and should be easier to find. I think I'm right in saying (but don't take my word for it) that the yam F50 gearbox will also fit and that's also 13 spline.
The big yamaha 60/70 box with the 2.33 is physically larger and therefore has much more drag. It takes 15 spline props.

I'm assuming yours is a long shaft motor? If so you want the gearbox from the 55 yamaha/mariner (same engine).

[yammi]

I have now in my hull a 60 enduro extra long shaft but i have a 70 to in part out ... he was the same spline because i have put the propeller on the 60 enduro ... and maybe the 2.33 is better for drag but just to put more pitch ?

[Roflhat]

They will have the same gear ratio.
Pitch is relative, with a higher gear ratio (1.71 instead of 2.33) you don't need to use such a high pitch propeller to go the same distance forward.

Have a go at putting numbers in here - http://www.csgnetwork.com/marinepropcalc.html

[Hounddog]

They have offered good advise:
First you switch the reed stops. The 60 hp stops are bent in. Use 70 hp stops.
Put 70 hp jets in the carbs and raise the timing 2 degrees.
Find a 70ces head. They are the best. The small gear case is better. They made three different lengths. The short, a medium and a long. Find the medium. It bolts on without any modification. The were on the short mid Mariners that had a spacer. They are mostly a 1:84 ratio. Being a commercial model your motor likely has the non rev limiter box. These CDI systems can last forever so long as you do not rev them over 7500 rpm of long periods of time. I would try a 18 x 12 chopper prop.

[Roflhat]

Hi Hounddog,
is there any advantage to running a hydrotec head on a CES or is it the same design?
Cheers

[Hounddog]

Hi Hounddog,
is there any advantage to running a hydrotec head on a CES or is it the same design?
Cheers

I think the HydroTec head is just a cut stock head. The true 70ces head is different. One thing you need to watch is the jetting. The ces head needs a lot of fuel. The 100% original 70CES runs the small 70 hp carbs with 90 hp jets. The motor runs fat and idles at approx. 1200 rpm. That is the way it was designed to run. Many think running the larger 90 hp carbs will help. WRONG! Unless you have other mods done and you know more about the motor than the guy in Japan who designed it, Run the small carbs with the big jets. The motor is good and it lasts. Forget the 100 hp rumors. They are FALSE. On a prop dyno a pure stock 70CES will pull 1150 lbs on load. That translates into 70 hp at 6300 to 6400 rpm. The power curve really drops in the higher rpm range. The motor is a basic fishing motor with performance add ons. It still has the heavy crank and rods. They match up well against the Formula E OMC motor.
The yamaha has more low and mid range, the OMC more top end. Off the dock the 70CES will out run the OMC to the first pin. After that it is a battle.

[Hounddog]

We raced against the 49 cubic inch OMC and had good success. Mainly because the competition was so wrapped up in the 100 hp BS
about the 70CES from Europe that they NEVER looked at what they could do legally to their own motor to beat it.
So since we do not race against them any more here is the solution.
First The OMC is a BETTER designed motor.
Second the early OMC blocks have better stock porting compared to the later blocks [run 1976 block]
Third you can find PERFECT cranks and matched light rods for the OMC
Fourth you can run the 1973 65 hp lighter flywheel
Fifth you have two carb sizes to select from. The smaller carbs take away the yamahas hole shot advantage on the shorter ovals.
The larger ones have a 3 to 4 mph top end advantage over the yamaha
Sixth props..there is far more selection for the OMC compared to the Yamaha and there is far more feedback information on the web.