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Keihin carburettors
westf27 - 31/7/08 at 05:52 PM

Zrx 1200 carbs..does the adjustable pilot jet underneath richen or weaken the mixture as you unscrew it


whitestu - 31/7/08 at 05:54 PM

On my Mikunis I was working under the impression that unscrewing weakens the mixture as it is an airscrew. I suspect most bike carbs are the same.

I could be wrong though.


bigrich - 31/7/08 at 05:55 PM

almost all bike carbs richen as you unscrew the mixture screw,

You now have a dilema LOL

[Edited on 31/7/08 by bigrich]


BenB - 31/7/08 at 06:02 PM

Yup. Richens as you unscrew. More fuel


westf27 - 31/7/08 at 06:06 PM

http://www.ooracing.com/tuningTips.htm#mainjet

have just read this and it gets rich as you screw it in ??


mistergrumpy - 31/7/08 at 06:25 PM

My ZX9 Keihin carbs get richer as you screw it in. Checked with Haynes manual and that says the same.


takumi - 31/7/08 at 08:34 PM

on my Keihin carbs (cvk40 i think) screwing in makes it lean,

unscrewing makes richens it.

the screw is the final control on the idle fuel circuit.

Just had to screw it all the was in to pass my MOT emissions, way under the limits..

Half a turn out sounds alot nicer.!


coozer - 31/7/08 at 09:19 PM

Unscrewing leads more air in leaning it off. It only affects idle and a little bit above it.

At SVA my HC was over 1200 and unscrewing the needles dropped it down.


Roman - 1/8/08 at 02:00 PM

Not sure but this site may help.

Look near the bottom of the page.