Board index Flathead Power-Technical Questions, Answers, and Suggestions Knuckles carb


Moderators: Curt!, Pa

Post Tue Aug 13, 2013 10:39 am

Posts: 8
have a 47 el project and need a carb. not a show bike so i don't want to spend the money for a linkert. thinking about a mikuni but i need to know what specs, jet sizes, which needle, 36 or 38. bike is a chopper, standard bore, andrews n cam, 7.5 t0 1 pistons, stock timer. don't want a hotrod bike just a good runner thats easy to start. any sugestions would be appreciated. thanks CC

Post Tue Aug 13, 2013 10:55 am

Posts: 536
Location: Wa, USA
The Kehin CV used by HD from the mid 90's and later is a good choice. Easy to tune, and a very good starter. My UL starts first kick cold with a CV.

Post Tue Aug 13, 2013 1:26 pm

Posts: 8
i have a cv 40 on the shelf, i'm worried that it's to large a throat for a 61" stock motor. can i tune it down to work, will that motor have enough vacuum to work the slide? what jets do i need? thanks for the help. cc

Post Wed Aug 14, 2013 5:20 am

Posts: 1642
Location: Interlaken, NY USA

If you're shopping the swap meets, most of the 38mm VM's are setup for harleys. The 25 pilot and 130 main jet are a good start, and that's in the neighborhood of what many of my swapmeet finds have. I'm running them on my UL's, 47 knuck 80", and 65 pan. They're first starters too. 38 would be a good fit for the 61.
The CV's are a good choice as well, CV's generally are good carburetion, in that the variable venturi does a great job of adjusting to engine load. Your call.

Post Fri Aug 16, 2013 11:43 am

Posts: 8
forgive my ignorance frankenstein but when you say vm's are you referring to a mikuni carb, is that the model ? i don't have much experience with anything other than ss and amal carbs. you mentioned the cv 38, thats what comes on an 883 right. thanks for the help. CC

Post Sun Aug 25, 2013 8:32 am

Posts: 1642
Location: Interlaken, NY USA

Sorry for the confusion, Yes, VM is the Mikuni round slide type of carb. Good all around carb. The CV refers to the constant velocity Kehin? fitted as stock to Harleys for years and referred to in a previous post.
By their nature, (variable venturi) the CV's are a very flexible carb and could be made to work on the 61" knuck. Don't have the experience myself, although I did use SU's extensively in my youth, when my right knee would bend around them. :D The CV 40 is just an evolutionary refinement of the old SU.

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