Hi , can you do a 2stroke upgrade from 40 to 60 with a carburetor conversion , I'm sure it's the go to 50 but heard it's the go to 60 as it's the same block, thanks for the no bull**** replys

Find a yammie outboard mechanic & get them to double check parts list against your outboards number. Just because same block doesnt mean much, they tend to get power from different carbies, reeds, powerheads & gearboxes. Sometimes it can cost half price of new 60 to do upgrade, I know for mercs the carbs are crazy expensive so is just as viable to sell 40 & get new 60 for similar money as upgrade.

Yer I feel your pain, have same thing with 40 merc which I got when bought my dad's boat with 100hrs on motor- i'm almost done modding boat to how I want & looked at power upgrades at same time. In my case 40 to 50 is carbs & reeds & likely will only get a few hp at that as the hp rating is a minimum so your 40 might be putting out 48hp then you spend $1500 to get an say an extra 5. Then you may only gain on top end which if you are doing long trips probably don't use to conserve fuel/drive to the conditions. If you are going to spend the money you need someone to tune that really knows what they are doing, most outboard mechanics don't.

Have a real good look at your boat's performance with the 40/2, the only 60/4 which gains anything of significance is the suzuki which you take a long term risk with as covered by Haines group which could stop support or go bankrupt at any time in the future. I compared my top end & fuel economy of similar hull shapes to most 60/4's & I only gain a little and only lose out on price of 2 stroke oil which is offset against higher service costs.

My personal choice is to change prop to account for boat changes now & then wait for the new gen yamaha 60 to be released. Once you've bought and used an outboard the bulk of depreciation has already happened so figured may as well use & wait. You could go a 60/2 for cheaper & the performance you really want but the move is already on with some waterways limiting them in hp and only to 4 stroke or e-tec so personally I wouldn't get another 2 stroke.

The yammie 40 2 stroke is a sweet motor, the cheapest performance improvement could be a new prop particularly if your long trips are while running loaded (mate of mine gained several knots top end with new prop on his yammie 40).

mark is spot on. Huge change in performance can be made through changing props. Changed props on my Yamaha 50/2 and went from 38knots to 46 knots striaght up. But if you want to tow the original (slower prop) is better, due to shallower pitch. ie more grip.

you can use this calculator to work out the performance you will get from different props.
www.csgnetwork.com/marinepropcalc.html

cauncy said..
Hi , can you do a 2stroke upgrade from 40 to 60 with a carburetor conversion , I'm sure it's the go to 50 but heard it's the go to 60 as it's the same block, thanks for the no bull**** replys

Short answer is NO!

Rattlehead said..
The 40 and 50 are the same displacement , the 60 is a different engine , so no can't turn a 40 into a 60 without spending big .$$$$

Repitch the prop.

Even outboard engines with a same block, so say the 40 and 50 can't be readily converted up in hp simply. You would need to also strip the engine and hone out exhaust outlets and air intakes, carbies, linkages, the list goes on. Their are a few engines I'm led to believe now that can be converted with a simple ECM change. But it needs to be normally a EFI, at best, fully computer controlled but even then I'm still sceptical.

A customer on a boat i have with a 90hp Suzuki changed the ECM to a 115hp and it now runs a much larger prop and pulls much harder. In fact the same as a 115 but the ECM was still a few thousand dollars, new prop so for the $3000 odd in cost it may still not have been value for money..

Hopefully that all makes sense..