Re: Yamaha 6hp to 8hp
hi, I am looking for the same info myself. I assume it will be more than simply the linkage.
I have a 15hp honda to change it to a 20hp engine you need to change a jet in the carb and change the cdi as it limits the revs. This costs pennies for the jet and depending on your local dealer nothing to reset the cdi or $400 for a new cdi. I did both, end result extra 0.5mph on my boat, bigger wake, more fuel, as the hull is displacement not unexpected.
the 6hp yamaha is on a inflatable, 2 more hp should be more useful...
Based on y Honda experience I would assume on the yamaha that as a min you would have to change cdi.
I got the honda info from the shop manual, purchased on ebay, it detail the cdi, carb and linkage details and best of all the part numbers to buy the replacement bits... The local dealer had lost the honda dealership and was happy to swap CDIs for a minimal charge...
hope this helps....