Air Intake

[kifferznew]

My 350 is stock. With the cover to the air box removed the thing screams i estimate in the neighborhood of 50-65mph maybe more. With  the cover on maybe runns at two thirds that. Its a new air filter is that normal?

[hoodlum]

Yes it is normal....The intake is restrictive...There are many posts and pics of people doing dual intake hoses to solve this problem...Just a note though,if it runs good with the lid on,and doesn't sputter,chances are you are running lean when you remove the lid...If you run it with the lid off,you need to increase the size of your main jet in the carb....Otherwise you will melt your piston or sieze the engine....

Hoodlum

[LiveWire]

The single tube from the upper air box is restrictive. You can cut the face out of the upper air box and convert the intake side of it to a second outlet with another hose. Realize that you are leaning out your air fuel mix so you need to check your jetting to make sure it is not too lean.

The stock slow jet is a 52 which is too large making it rich at idle. So much so that fuel will pool in the bottom end making it seem rich at larger throttle openings. Often people will lower the main jet or remove the air box lid and it runs better good until the pooled fuel is burned during a long run. Then the engine fries. The jetting needs to be verified at each throttle position. A 45 slow jet is usually a good choice.