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750 Roadster twin to single carb swap

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Hi, does anyone have a copy of the RGM tuning sheet that came with their 2 into 1 manifold? I have a Concentric 930. At present it has a 220 main jet and a 3 1/2" slide. I'm going to use this and need to find out what I need to do to. I'm not concerned with losing top end as my days of racing about the place like a maniac are over.

Ta.

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The Mercury 650 used a 930 Concentric but with a much larger main jet.  I run my 650 with a single 930 Concentric and a 270 main jet plus K&N metal mesh filter.

Personally I would suggest a bigger carb for a 750 engine. At least a 932 or even a 934 Concentric.

930 Carb

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Hi Norman,

RGM has info on single carb on their technical info drop down menu on their website (see photo of page 2 attached). They recommend 32mm carb though, so not sure of settings for 30mm. Hope this helps.

Cheers, Mike

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When I went single carb on my Atlas, I popped the redundant carb in my spares box and just fitted the existing carb with no changes. Works a treat. 

34mm is too big for a 750 in my opinion. 30mm is quite big enough.  

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I used a 32 Concentric on my Mk3 850. works very well for my use.

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Thanks for replying everyone.  I'm using the right hand carb, 930. I'm going to try using it as it is, as it works fine. If I need to make an alteration I will. However, if it worked OK on one cylinder, I can't see how it wouldn't do both.

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It boils down to how efficient you want your engine to operate and perform under your right wrist when choosing the right carburettor for your needs. All of the choices above will work with differing performances as a result.

Two into one inlet ports will want to pull more air through a single carb' than just one so jetting up is the way to go. By how much -------?  Cut away, ditto.

Amal will more than likely have the correct data for you.

 


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