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Old 04-02-2013, 09:36 AM   #1
Hookalatch OP
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Joined: Feb 2006
Location: Cottonwood, CA
Oddometer: 403
Stock 40mm Bing jetting

I am in the process of converting my 1984 R80RT into an S type model.
I am using parts from a 1982 R100RS. Presently rebuilding the 40mm Bings.
They are the correct carbs for a 82 RS according to the Bing book.
Bing calls for a 160 main, 45 idle jet, a 2.66 needle jet, and the needle on the 2 groove.
What I found in the carbs was a change to a 2.68 needle jet and needle on the 3rd groove,
The Bing book also states many models came jetted lean from the factory.
I need to replace the needle jet and needle and don't know if I am better off with the stock recommendations or increasing the needle jet size with or without moving the needle.

I am familiar with carb tuning practices but since I will have never run the bike with these parts I need a best guess starting point. I do not want to change the main or idle jets until I get the bike running. The needles were totally corroded and have to be replaced. I will go with Bing's recommendations on the 2.66 needle jet and needle on #2 unless the list experience indicates I would be better starting with with a 2.68 and richer needle position. I am using all stock R100RS parts from the airbox cover thru the cylinder and piston.

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