TOPIC:

How do I know which pilot jet size is correct for my carburetor, other than following what the FSM states?

Since you don't want to follow the FSM I guess you have changed something on the bike? It depends on what that is.

daveo wrote: How do I know which pilot jet size is correct for my carburetor, other than following what the FSM states?

Not sure if this really answers your question or not, but if the idle speed drops with the mixture screws about 1-2 turns out and drops again with them 3-4 turns out, then the pilot jet is the correct size. If it doesn't drop on the lean side, then your pilots are too large (or you have an enricher leak), and if it doesn't drop on the rich side, they're too small (or you have an air leak).

TheForumTroll wrote: Since you don't want to follow the FSM I guess you have changed something on the bike? It depends on what that is.

The engine has an 84 ZN (GPZ) bathtub head and GPZ camshafts, with a V&H header, and Dyna 2000 ignition. Beneath the head the engine is stock.
The carbs had 132.5 mains and 40 pilots since the head was changed back in March, and it seemed to be running slightly lean. Yesterday I changed the pilots to 42.5 to see what effect it has.

jackleberry wrote:

daveo wrote: How do I know which pilot jet size is correct for my carburetor, other than following what the FSM states?

Not sure if this really answers your question or not, but if the idle speed drops with the mixture screws about 1-2 turns out and drops again with them 3-4 turns out, then the pilot jet is the correct size. If it doesn't drop on the lean side, then your pilots are too large (or you have an enricher leak), and if it doesn't drop on the rich side, they're too small (or you have an air leak).

Too blubberish with 42.5 pilot jets, so I'm back to crisp response with size 40. This time Genuine Mikuni...precision made with the hole exactly in the center:)