1970-1979 Ski-Doo Snowmobiles Service Manual, Page 109Get this manual
CHAPTER FIVE
9Slide air screw spring over air screw and install air screw gentlyCAUTION
Do not force air screw or seat damage may occur
10Install throttle stop screw with springInstall screw until it is just flush with inside of boreAIR INTAKE SILENCERS
Air intake silencers are installed on snowmobiles to quiet the sound of rushing air and to catch fuel that spits back out of the carburetor throatRefer to Figures 21, 22, 23, and 24 for typical examplesThe silencer is not intended to filter incoming airOperate snowmobiles only in clean, snow covered areasCAUTION