Idle Pin & Spring

[Rkymtn57]

1998 Mariner 115 4cyl. 2 stroke 0G690899
Could someone please tell me why carbs. 1 &2 have Idle Pins and Springs and 3 & 4 have only plugs?

 

[Faztbullet]

You have the 2+2 motor....simply put the bottom two carbs have modified idle circuit . Bottom two carbs kick in at about 2000rpm with the help of an accelerator pump on throttle lever.