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float height FCR

Joined Sep 2006
989 Posts | 23+
Hayle Cornwall
Hi All,

This is an interesting one, if you check your float height on a FCR by the down load official manual it says the float must be parallel to the carb body, if you go to the Keihin carb site the float height is set at 9mm, they are not the same.
If you go by the manual when the float is parallel, the height only measures 7mm, so how many of us use the parallel method or actually measure the height to 9mm?.. interesting.
2mm makes a hell of difference on bottom end performance, I've tried both settings, the 9mm setting works the best as you would expect it's Keihins base setting.

Regards

Sparks.
 
HI Sparks,

I use the parallel setting myself.

I have worked on a few different FCR's for people and was amazed to find the float level set very low from the factory, perhaps 5mm, just a guess since I didn't really have a way to measure it.
 
DaleEO said:
HI Sparks,

I use the parallel setting myself.

I have worked on a few different FCR's for people and was amazed to find the float level set very low from the factory, perhaps 5mm, just a guess since I didn't really have a way to measure it.

Hi Dale,

Simple really I should of taken a photo, all i did was take a piece of my thick winding wire about 50mm long and bent each end down 9mm, place the 9mm legs onto the carb body and the span across the float, with the manual setting there is roughly a 2mm air gap.

Regards

sparks.
 
Right,

Should have thought of that myself!! And just for reference, the Honda manual also dictates 9mm on the float height.

Did you have to, or feel the need to make any jetting, or pilot screw changes based on the float height changes?
 
DaleEO said:
Right,

Should have thought of that myself!! And just for reference, the Honda manual also dictates 9mm on the float height.

Did you have to, or feel the need to make any jetting, or pilot screw changes based on the float height changes?

Oh yes, with the floats set by the manual I was always on the rich side of things, had to have smaller openings on the FS and a larger openings on the PAS, now set at 9mm the pilot settings have fallen into place, but bearing things in mind it will now lean things off across the whole carb.
It's always been the pilot circuit that has been giving me the the most grief as we've spoken about this before.
Testing still goes on will it ever end???.

Regards

Sparks.
 
It will never end............LOL!

Because perfection is a direction and not a place. So that road will go on forever for those with drive and the desire to have or be the best they can.
 

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