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Altering fcr 41 to work with stock bore

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Hi all,

I have an fcr 41 i purchased for a 470 stroker build that didnt work out.

I was going to put the fcr 41 into a stock drz 400 with a yoshimura pipe and 3x3 mod.

Can i cover off the throat of the fcr 41 to approx a 39mm diameter? Would it work? I could trim some aluminum and adhere it on with gasket seal.

Or should i just put it in as a 41? It will probably work better than the stock mikuni anyways right?

 

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You know, people have tried that in various ways but I just do not see it working satisfactorily.  The diameter where the fuel enters the air stream is the critical diameter.  Bushing it down before or after that really does not do much.  Might as well just fit it as a 41mm.

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I also put in an fcr 41mm on my DRZ400SM K9 model.I ordered original Keihin pilot jets,main jets and a selection of needles.I also played around with pod air filters,standard air filters and k&n air filters.Although i got the bike to start,idle and run properly i never got the same top end out of the fcr as opposed to the standard Mikuni Bsr36mm carb.Bike is standard,3x3 mod and Fmf exhaust.I have done the JD kit on the Mikuni though.Granted the low end power is a lot better with the Fcr but the increase in fuel consumption was a deal breaker and i am back to my Mikuni.The 39mm Fcr is the way to go though.

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