Was researching my new to me motor (1966 mercury 60 6hp) and read that it is possible to convert it over to have 9.8hp since back then the only differences between the 2 and also the 15hp is the size of the Jets in the carb. Anybody know any truth to this? I am taking it out this weekend to test run it with the current 6hp carb. But if it for some reason doesn't go faster than I'd like for it to then I was debating on replacing the carb with a 9.8hp carb. As long as it's not too much. I know I should've put this thread in the boats and motors section but I posted my last thread in bot this section and that section and got much more feedback in this one...

If you can figure out what size jets the uprated carb have you may be able to get the existing carb re-jetted or have the jets machined to the correct diameter. You may have to run a hotter spark plug to in order to compensate for the extra fuel being pumped in to the motor. Having a re-jet done may be cheaper than buying a whole other carburetor, and I'd imagine finding one of that vintage in the correct configuration may be difficult.

I converted my 88 Yamaha 9.9 to a 15 hp. just by changing the carb and also the reeds to a 15 hp.
If it's the same as my Yamaha that everything in the motor is the same then you may also have to change out the reed assembly as well.
Mine little 9.9 hauls butt. I had to change it out because the bowl on the old 9.9 carb cracked, so it was a no brainer.

Well luckily I've located 2 or 3 carbs from 9.8hp of my Era and surprisingly they all are less than 50 bucks. All the parts I've found for my motor including the rewind starter and ignition system for less than 80 bucks each most parts going between $10-$50 I'm probably gonna try and buy as many replacement parts as I can that way I have them on hand just in case since they are obsolete.