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I am trying to find the correct Main and Pilot Jet settings for my mod. I am running the Athena 440 big bore kit with an open air box K & N air filter, full system yosh exhaust, and hot cam intake cam. Stock Main is 150 and I have moved up to 160. Stock pilot is 22.5 and I have not messed with it because I have no idea what to change it to. ANY SUGGESTIONS? I have the dynojet kit, but all it has is main jets. I can play with them all day long until I get the right setting, but I have no idea where to go with the pilot, and I have noticed they are a little more expensive, so if anyone can give me an idea where to start, it would be appreciated.

PS. The problem is that I am running way to lean. Constant backfiring when letting off the throttle, extreme heat radiating from the motor, cherry red exhaust pipe when at idle, and hard to start. I was told its mostly the pilot jet due to the problems being most obvious when at partial throttle.
 

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It sounds lean, and your probably right about it being the pilot. I personally got a bigger carb because with out that the big bore can't "breath" quite right.

If i would have stuck with the stock carb, then I would talk to Paul at advantage cycles. He has a fuel screw for the stock carb, and it replaces the one that requires a screw driver. Advantage Cycles.

Now if your stuck on sticking with the stock carb, the next size up is 25, then 27.5. I would get the 25 Pilot Jet and then a few main jets. Maybe you can get the stock carb to work, but just remember that you'll be robbed of top end. It doesn't open like FCRs and Edelbrocks do. Also, you may have trouble with emptying the float bowl after running it wide open.
 

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you really need a 25 pilot in there and approx. 2.5 turns out on the fuel screw on the bottom of the carb

A 165 dynojet main jet sounds about right too.

You need to use their needle and up it some. I believe you have to use all of the stock shims with their needle. Read the info they give you.
 

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Discussion Starter #4
Originally posted by 2003z440@Dec 19 2005, 09:29 AM
It sounds lean, and your probably right about it being the pilot. I personally got a bigger carb because with out that the big bore can't "breath" quite right.

If i would have stuck with the stock carb, then I  would talk to Paul at advantage cycles. He has a fuel screw for the stock carb, and it replaces the one that requires a screw driver. Advantage Cycles.

Now if your stuck on sticking with the stock carb, the next size up is 25, then 27.5. I would get the 25 Pilot Jet and then a few main jets. Maybe you can get the stock carb to work, but just remember that you'll be robbed of top end. It doesn't open like FCRs and Edelbrocks do. Also, you may have trouble with emptying the float bowl after running it wide open.
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As for the stock carb.....I am not dead set on keeping the stock carb, however, with my financial situation as it is right now, that might be the case for a little while. That being said, I am going to try to start out the cheap route with the jetting. But when I am ready to purchase a new carb, what carbs do you recommend? (mm size and brand names)
Thanks.


Also, as for the jet sizing, do you think only bumping up 1 or 2 pilot jet sizes would do the trick?
 

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Discussion Starter #5
Originally posted by z400Clone@Dec 19 2005, 11:42 AM
you really need a 25 pilot in there and approx. 2.5 turns out on the fuel screw on the bottom of the carb

A 165 dynojet main jet sounds about right too.

You need to use their needle and up it some.  I believe you have to use all of the stock shims with their needle.  Read the info they give you.
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Is the fuel screw the small screw in the tube protected by a gold cover that has to be drilled to remove to allow access to the screw head?
 

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Originally posted by DTown911Dispatch@Dec 19 2005, 11:44 AM
As for the stock carb.....I am not dead set on keeping the stock carb, however, with my financial situation as it is right now, that might be the case for a little while.  That being said, I am going to try to start out the cheap route with the jetting.  But when I am ready to purchase a new carb, what carbs do you recommend?  (mm size and brand names)
Thanks.
Also, as for the jet sizing, do you think only bumping up 1 or 2 pilot jet sizes would do the trick?
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I know what you mean. I got my big bore, and had to wait a while for the carb. I got a used edelbrock, and so far, i like it. I haven't had time to test it out or tune it, but the few times i did ride, it felt strong. I would recommend getting one used, because new cost quite a bit.

As for jets. I always used Mikuni and they can be bought in several places (also, i think its the easiest to find). And like i said earlier, i would start with a 25 jet if the 22.5 doesn't work for you. (they are in increments of 2.5)

As for main jets, if you don't have a jet kit, just get the next few sizes bigger than what your using.
 

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Originally posted by DTown911Dispatch@Dec 19 2005, 11:56 AM
Is the fuel screw the small screw in the tube protected by a gold cover that has to be drilled to remove to allow access to the screw head?
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my fuel screw just had a rubber plug over it. I didnt have to drill...so thats kool.
 

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my fuel screw just had a rubber plug over it. I didnt have to drill...so thats kool.
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Did you ever figure out what jets it was that you needed? I'm having the same issue with mine. Thanks
 

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Thread is from 2005. The "new" button up in the top right corner will get you to more relevant threads.
 
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