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VFR750 VFR750 is offline
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Join Date: Mar 2004
Location: Windsor, CT
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I think you will find it is impossible to lean it much more than 11.5:1 at cruise and still have a reasonably stumble free transition. It is just how carbs, especially weber/PMO/Zeniths work.

There is a reason they got such poor mileage and polluted so much. They were always pretty rich. Now we have AFR gages and discover how sloppy they really were.

Wot is different. 12.7 to 12.9 best.

There is also why CIS and motrinic offered better mileage. They can do a better job of managing transition. So they can run a lot leaner in cruise.

Of course this is my input. Having spent the better part of four years mapping my zeniths, with both zenith and weber IDA transition ports, I concluded that is what it is.

Rich cruise equals good transition. 11.5:1 is about right.
Old 10-28-2014, 09:55 AM
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