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 Posted: 12-20-2021 10:27 pm
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Esprit2

 

Joined: 05-01-2005
Location: Minneapolis, Minnesota USA
Posts: 573
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Paul,
Since the beginning of this thread, you have never mentioned which Idle Air Corrector (aka, Idle Jet Holder) is installed. You have listed a few jets from time to time, including the Idle Jet, but never any mention of the Idle Air Corrector.

So, direct question: which Idle Air Correctors are currently installed. For all your tuning, have you ever changed them? If you have, then from what, to what, and what were the results?

The Idle Air Corrector's basic part number is 7850-x, with the 'x' being a number from 1 to 10, indicating the size. The sizes aren't in numerical order from lean to rich... instead, they seem quite random:

Leanest -- 5 – 10 – 9 – 4 – 1 – 3 – 6 – 7 – 2 – 8 -- Richest (I posted that back in msg #10).

Stock JH Dellorto DHLA "40" throat carbs, both emissions and non-emissions, used 7850-5... the leanest available.

In general (very broad strokes), a 9XX on DHLA "45" throat carbs likes 7850-7. That's probably a little rich, and -6 should suffice, but the engine just seems to like -7... emissions requirements not withstanding.

Regards,
Tim Engel

Last edited on 12-20-2021 10:54 pm by Esprit2