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04 fat boy, 95 kit, s/e httc non ported heads, forged pistons, 211 cams, s/e air cleaner and going to 2-1 exhaust. When it was put together, two dealers told me 42 mikuni was enough carb. Runs good so far, but was wondering if a 45 mikuni is the proper size for this build?
 

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I bet either way it will work fine.
I remember reading somewhere probobly on the S&S site where
using a 100 hp kit if you used a "E" ( 40mm throat) and replaced it with a "G" carb (45mm) the top end difference would be 3 HP. Of course the "E" carb would have better drivability than the "G".
Mikuni has an extra fuel circuit and variable venturi (Slide) so the difference in low speed running would be minor between the 42 and 45 HSR Mic's.

joepenoso
 

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retired lt said:
04 fat boy, 95 kit, s/e httc non ported heads, forged pistons, 211 cams, s/e air cleaner and going to 2-1 exhaust. When it was put together, two dealers told me 42 mikuni was enough carb. Runs good so far, but was wondering if a 45 mikuni is the proper size for this build?
I'm doing a 98" build and had an interesting conversation with Pete at Zippers...you may find that 42 Mikuni, S&S Super E and your stock CV tough to tune...if you're successful in getting it to run acceptable you'll lose somewhere, top or bottom...though the Mikuni will work best. It was suggested to me that I'd want to upgrade to a 45 Mikuni, S&S G1 (modified G with a 3rd fuel circuit) or a 44mm CV for best results...(45mm CV???)
 

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Why did he say it was tough to tune?
The 44mmCV actually has a 42mm venturi.
The S&S"E" and stock CV have 39.5 and 39mm ventuis respectively.
Tuning any of the (Large or small) carbs shouldn't be any more difficult regardless of what you choose, IE. S&S G vs E
or MIKUNI 45 vs.42 Stock CV vs 44mm.Also the peak numbers assuming 100HP should be within 3 HP of each other.

joepenoso
 
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