Tatty motor upgrade

[d227517]

Hi Guys,

I just bought a boat and the 25HP on my 4m blufin struggles with 3 adults but with 2 adults goes fine. with 3 mates i thought it would obviously be slower gettin on the plane but should later get to decent knot speed but nope putts along.

the motor was checked and compression was good as expected for a motor thats only done 80hours

Im looking at upgrading my 02 tohatsu 25HP (M25C3) to a 40HP. just wondering if any motor would be compatible with the tohatsu steering box? or does it have to make for make?

or can i just change the prop to a bigger one??

any info is much appreciated guys.

Mark

 

[pvanv]

Re: Tatty motor upgrade

The 25C3 can be upgraded to a 30 very inexpensively.
Any motor that uses teleflex-style steering can use that same cable; RC boxes are however manufacturer-specific.
Higher prop pitch would hurt your hole shot acceleration; less pitch might help; depends on your present WOT RPM whether that would be acceptable.
What is the jack height? How is it trimmed?

 

[d227517]

Re: Tatty motor upgrade

Thanks for replying Pvanv,

im sorry but im a amateur with the outboard lingo
not sure how to measure the jack height.

its currently trimmed on the 2nd hole closer to the transam...if that makes sense.

also in the picture attached is that a teleflex or RC box

thanks again

 

[pvanv]

Re: Tatty motor upgrade

It may be best for you to get some experienced assistance with the height situation. The vast majority of Japanese outboards are so long that they need to be mounted above the top of the transom, so that the antiventilation plate is even with the bottom of the boat. Too low, and the bow rises too much (requiring the motor to be trimmed very low), and the extra drag also slows the boat. Too high, and the prop ventilates (draws in air), which the prop can't use to push the boat... and air is something you don't want in the cooling system, either.

Rigging the motor correctly will require a careful evaluation of the motor jack height, centering, trim, and of course the weight distribution of the boat itself. In the end, on-water trials are used to fine-tune the rigging in all cases, preferably with the aid of a tachometer.

Your picture has nothing to do with steering; it's the control box... has the electrics for starting and stopping, as well as throttle and shift. Not to worry; if you decide to purchase a different Remote motor (new), it will come with the box. Modern motors use the standard Morse-style throttle and shift cables, so those interchange.