Your starter valve AKA choke valve AKA enrichment plunger sounds worn. Carb may need a rebuild too but Check it out it’s on the side of your carb. The seal should be pliable and conical. You can’t replace the seal itself buy the kit for $40.
Don’t cheap out trying something else these quads don’t like aftermarket parts.
Don’t cheap out trying something else these quads don’t like aftermarket parts.