I have a 2 stroke 25 hp yamaha oil enjected motor that is about 8 years old, sorry not exact about age, it's on the beach in Mexico.<br />If I disconnect the top carberator the boat runs fine, but when both carbs are hooked up the boat will only go 5 mph. Do I need rebuild the top carberator? if so is it difficult<br /> It has clean gas and plugs<br />Thanks<br />John