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Wardy0589
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uk
Joined: 05/03/2011
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I Have a R51 (1938) and have managed to find 2 fischer amals, but the needles were different sizes. I guessed on the shorter one (52mm) and had another made, but it doesn't run right. Has anyone out there got an R5 or R51 running Fischer Amal 5\423 carbs who could tell me the needle length and jet settings? I'd be very grateful!

Wardy

R68
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Posts: 466
...I'm using Amal-Fischer

...I'm using Amal-Fischer 75/423 SL and SR on 1938 R51 motor 505590 with jet needle measuring 73mm, and I'm using clip position #2. I tend to like to run rich in midrange, so check if that clip position is factory recommendation. Some folks think the Amal-Fischer are too valuable to use, and substitute 22mm Bings. I cannot tell any difference when running with the Amals or the Bings. As for main jet on the A-F's, I think I'm using a 100 or 105, but need to check for you if necessary... As you may not be aware, Bing made a copy of the AF in 1938-40 because of reluctance on the part of german government to allow BMW to to pay royalty fees to a British company. These may be OEM of some R51.

Wardy0589
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Thanks for this

Hi there, thanks for your detailed reply. How do I know what model my A-Fs are? I presume they are 5/423 as stated in the manual, and they certainly fit the bike well (does it say on the carb, I cant find anything!). Could you send a pic of your carbs for me to compare? A pic of the needle would also be great

I reckon 100 main jets will do, and if your carb looks like mine I'll go for the 73mm. Thanks a lot for this, I may yet get the thing running well!

Cheers Chris

R68
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Joined: 08/20/2008
Posts: 466
The carb type is lightly

The carb type is lightly stamped on the flange. Best to contact me off list about this even more esoteric than usual topic?

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