Question re Pilot Jet size

[Frank Z.]

Believe i need to go up in pilot jet size, as bike runs/idles best with mixture screws at 5-1/2 turns out Currently running #45s, and wondering if i should move to next size up #47.5s... #50s... larger? Could employ the "order several sets and see" method, but figured the gurus here would have a sharper arrow.

Some info:
1980 GS1000S, mods include 1085 kit, street/strip cams, head mildly ported, 4>1 exhaust, factory airbox (w/out lid + K&N filter). Carbs are BS34CV, recent rebuild.

Bike runs great at speed; just wants more fuel at start-up/idle. Thanks for any insight. ?Frank Z.

[tom203]

Mixture screws at 5 1/2 turns out !! was there much/any difference from 3 to 5?
Are you sure your carbs are really clean ? -those idle circuit passages are tiny.
So I take it has a poor idle even warm?

[Frank Z.]

Mixture screws at 5 1/2 turns out !! was there much/any difference from 3 to 5?
Are you sure your carbs are really clean ? -those idle circuit passages are tiny.
So I take it has a poor idle even warm?

Thanks for reply, Tom. Def a difference from 3 to 5... very lean to strong steady idle. Carbs really really clean. Idles great when warm... at 5+ turns out

[chuck hahn]

Put new unran plugs in it and run it for about 20 miles at your "normal" freeway speeds out on the loop and see what they look like. Start at the 3 out spot.

I would say throw a colortune on it, but those who have tried one on CV carbs say it never shows any color changes as you turn the screws??? Don't know myself as I never have out mine in a CV carbed bike.

[Steve]

Even at 5+ turns, I think I would only change up one size to a 47.5.

I think I have seen somewhere that one size is equivalent to about three turns, so that would take you down to about the 2.5 range.

.

[Frank Z.]

Even at 5+ turns, I think I would only change up one size to a 47.5.

I think I have seen somewhere that one size is equivalent to about three turns, so that would take you down to about the 2.5 range.

Thanks, Steve! Will def give the 47.5s a go.

Put new unran plugs in it and run it for about 20 miles at your "normal" freeway speeds out on the loop and see what they look like. Start at the 3 out spot.

I would say throw a colortune on it, but those who have tried one on CV carbs say it never shows any color changes as you turn the screws??? Don't know myself as I never have out mine in a CV carbed bike.

Plugs look amazing; nice and ashy gray. Haven't got much useful feedback with ColorTune thingie... but daughter thinks the glow is pretty.

[Guest]

47.5 will be fine.
50 will be too big.

[chuck hahn]

Plugs SHOULD NOT be "ashy grey". They should be very lightly tan on the tips of the center porceleans.


Ashey Grey indicates a very LEAN condition.