FCR Needle Question

[mrquick68]

I'm replacing the needle in my FCR from the stock DXP to the EMN needle and understand that i need to step down my main jet from a 165 to 160 (i'm running a full open RS-3 at sea level).

Could someone (Eddie) explain how this works? I understand that the EMN must be tapered more, but i thought the needle pulled all way out of the main jet so that at full throttle the needle has no effect on what MJ to use? Please explain/educate me (us).

[Neil Claydon]

As I understand it, all the fuel that gets to the needle jet, first has to go through the main jet, so to an extent a smaller main jet will lean the needle range as well.

This is why you should re-jet a carb from full throttle downwards.

So,

1/float level, 2/ Main jet. 3/ Needle and clip position. 4/ Pilot Jet. 5/Fuel screw.

Each jet will affect the top end of the jet below it, due to the overlap between jets.

There is a diagram in the Dyno Jet kit that shows this.

The float level will affect all settings.

Neil. ?

[Wayward Son]

the tip of the needle is smaller.blocks the main jet less.needs smaller main jet to compensate.

[mrquick68]

I see. I will report on the DXP to EMN needle change tomorrow morning. See what kinda difference it makes. Hope I can tell.

How do you know where the float bowl needs to be adjusted too?

[Motor-N]

.......

How do you know where the float bowl needs to be adjusted too?

The Keihn spec that I have calls for 9 mm for all FCR's.

[mrquick68]

Bike runs about as good as I think possible now. Noticable difference in power. Pulls harder longer now. With the right jetting and the full RS-3, the bike has pretty impressive grunt. Gonna need cams next! Thanks for all the help TTers and Burned!