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Fatty Jetting


Brian060

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im gettin a set of fattys for free :cheers: and need to know where i should start my jetting. Im going to put the pipes on while im doing the top end so jetting is probably crucial because of break in. Im running a Pro Design foam filter/ adapter plate. Stock reed's and reed cages, and no lid. What should I start the jetting at?

 

Im also going from a stock bore to 20 over, will that affect jetting at all?

 

Thanks everyone,

-Brian

 

P.S. Does anyone know of a better place to buy weisco top ends than magic racing?

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I am not running the airbox lid. If you run the lid, id start at a 300 main and work down. The engine breathes a lot better without the lid. Just be carefull runnin through puddles and shit. And also when washing your bike. I'd keep the lid and put it on when washing your bike. :D Id also suggest an outerwear if you dont have one. :cheers:

Edited by Hilarious
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While we are on the subject of carb settings with FMF fatties, I gotta ask you guys a question. Do ya'll have a flat spot? I've pretty much got my carbs dialed in and it runs great. Does not overheat or anything. Nice chocolate brown color on the plugs. But...i've got a flat spot. It happens at a certain RPM before the powerband and does not pertain to any certain throttle position. I have stock needles and it did this prior to installing the v-force 3 reed cages. I'm thinking its just the nature of the pipes. :shrugani: I've changed the needle clip position up and down and it runs the best in the stock (middle) position. It also has a pretty good, crisp off idle response. Other than that the thing really runs great and eats the fuel up like a mofo. One more thing, I just gotta say that the finish on the FMF's suck. :cheers:

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While we are on the subject of carb settings with FMF fatties, I gotta ask you guys a question. Do ya'll have a flat spot? I've pretty much got my carbs dialed in and it runs great. Does not overheat or anything. Nice chocolate brown color on the plugs. But...i've got a flat spot. It happens at a certain RPM before the powerband and does not pertain to any certain throttle position. I have stock needles and it did this prior to installing the v-force 3 reed cages. I'm thinking its just the nature of the pipes.  :shrugani:  I've changed the needle clip position up and down and it runs the best in the stock (middle) position. It also has a pretty good, crisp off idle response. Other than that the thing really runs great and eats the fuel up like a mofo. One more thing, I just gotta say that the finish on the FMF's suck.  :cheers:

415303[/snapback]

A lot of times you can get a lot of dead spots out w/ jetting, but you will have some sort of dead spot w/ just your mods and pipes...the more of a high rev pipe you get, the more of a dead spot you'll get...Midrange pipes eliminate that dead spot.

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Guys, im gonna be running pro design w/ uni filter, no air box lid.  Stock reed cages with boyseen reeds, ADVANCED TIMING 4 degrees, and fattys with powercore II's.  I need to know what mains to buy and what pilot jets to buy.

 

                                                                              Thanks again,

                                                                                    Brian

415597[/snapback]

Stock pilots, 290 mains, raise your needle to the 4th clip from the blunt end...

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Brian, I got fatties ,power2's running 280 main stock 25 pilot, middle slot on needle, open box K&N with outerwears and she purrs running sea lavel on the lakeshore of Lake Michigan. Tim

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