My engine did not come with a muffler gasket, and neither did my Bisson Pitts muffler. I have seen where others have made gaskets. Do I really need to have a muffler gasket?

I am pretty ignorant when it comes to engines. Does this engine have an internal pump? If not, do I need to purchase an aftermarket pump to use this engine?

Thank you!

I never use a gasket. A little high temp silicone on mating surface and bolt threads. Very little is needed!!

A usual 120ax will use pressure from the muffler to pressurize the fuel tank. If your tank is located far from the engine you may want to look into a perry pump. Such as a 3d plane where one might put the tank on the CG instead of at the firewall.

The 120 is a lot of engine and I would advise you seek some local help since you are asking these questions.

I use Yamabond 4, wherever there is not a gasket. You can get the product at any Yamaha motorsports dealer, it works great.