over rev/popping

[captainQ]

I swapped over a 1986 20hp evinrude from a 20 hp to a 30 hp this weekend. I changed the intake and the carb. It starts ok but it's idle is high and it is not constant. Meaning it will rev up, then pop and sputter up and down.

Brand new carb. Is there a timing adjustment or something. It had a broken timing advance spring and i replaced that as well.

THanks..............

 

[restornator]

Re: over rev/popping

you probably need the exhaust tuner from the 30hp as well.

 

[blimp]

Re: over rev/popping

sound a bit like an air leak to me. I would carefully check around the intake manifold and carb-intake gasket for leaks. You can spray carb cleaner/wd40 around the seal and if it affects the engine at all, you have found your leak. I think the intake manifold->reed gasket needs a liquid sealant, but I am not positive.