2003 3 cycl. tohatsu 40 hp.

[duckjunkie]

can anyone tell me if this 2003 40 hp. 3 cycl. tohatsu can be upgraded to a 50 hp. and what would be involved. both engines are built on the same block but i know the timing is different on the two engines and the rpm range, but being an automotive mechanic for 35 years i know there is somtimes a difference in the cyclinder porting on outboards. i have the motor on a 17-56 f&f and could use a little more power. back years ago when mercury was producing the seapro line i knew a mercury dealer that was converting 30 hp. seapros to 40 hp. he said the only difference was that the 30 hp. seapro had a restrictor plate under the reed valve pack that limited how far the reed valves could open, so remove the restrictor plate and suddenly your 30hp. became a 40hp. i know the chances of it being something that simple on my 40 hp. tohatsu are slim but you don't know until you ask. but if rejetting and adjusting timing was all that was invovled that would still be a fairly easy fix. thanks for your time,

 

[pvanv]

Re: 2003 3 cycl. tohatsu 40 hp.

Modification depends on the model, not the year. What is the precise model/serial?

If it is a TLDI, that is model MD40(A or B), it IS possible, but not cost effective, as it would require both a pricey ECU and the 3-throat throttle body.

If it is an older carb model such as an M40D, the 3 carbs are different, the intake manifolds (and reed blocks) are different, and there are timing differences, but the blocks interchange.

For parts catalogs, see Elvin's website at http://www.internetoutboards.com/PartsCatalogMenu.htm