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Old 04-03-2013, 02:12 AM   #3
Brevis illi vita est
Joined: Jun 2010
Oddometer: 4,609
Originally Posted by Hookalatch View Post
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.

I would set it up with the stock jetting for the R80 id you have an R80 top end. Just buy both needle jets if you are ordering, they're cheap. You want to want to run as lean as you can consistent with not overheating, knocking and making good power. Nothing like trying both. You can switch them in a moment by the side of the road.
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