2-Stroke Carb Question

[SideW@ys]

I have twin 1998 130 hp yamahas (S130TXRW). Over time they have become difficult to start cold. Now need starter fluid to fire up when cold. I pulled the carbs on one of the engines and noticed 2 of 4 orifices were plugged. They are part # 14 (Jet, Slow Air Bleed) on this diagram

http://yamahamc.partsandwarranty.com/SyndicateNav.cfm?NodeID=1407496&Page=1

What exactly do these jets do? Do they supply fuel when the choke plate is closed?

Also, what does part #20 (Screw, Air Adjustment) do? If I adjust it, what happens (just curious)?

Thank you for you help. I have a manual on order but it won't be here until later this week.

 

[Natty Light]

Re: 2-Stroke Carb Question

I have twin 1998 130 hp yamahas (S130TXRW). Over time they have become difficult to start cold. Now need starter fluid to fire up when cold. I pulled the carbs on one of the engines and noticed 2 of 4 orifices were plugged. They are part # 14 (Jet, Slow Air Bleed) on this diagram

http://yamahamc.partsandwarranty.com/SyndicateNav.cfm?NodeID=1407496&Page=1

What exactly do these jets do? Do they supply fuel when the choke plate is closed?

Also, what does part #20 (Screw, Air Adjustment) do? If I adjust it, what happens (just curious)?

Thank you for you help. I have a manual on order but it won't be here until later this week.

Before you buy anything I would run a tank of gas through there with a higher than normal dose of Yamalube Ring Free.

 

[SideW@ys]

Re: 2-Stroke Carb Question

Thank you, will do. Just waiting on replacement carb bowl gaskets to arrive.