FMF System w/ Barnum Airbox Kit

7 replies to this topic
  • clark4131

Posted April 10, 2005 - 06:59 PM


I just installed the Barnum's Pro Airbox Kit to complement my PowerBomb/Q2 setup. I figured the bike should suck as well as it blows :naughty: . One question though...I was running a 170 main, #40 Leak and Boyesen Quickshot which totally cured my low end bog, but with the addition of the Barnum's, the bog is back. Also, the bike no longer responds to any fuel screw input. I've gone all the way up to a 178 Main and that cured most of it, at least it doesn't stall now with a snap of the throttle from idle. I was thinking about going to a 180 Main and having a 182 on hand just in case. My thinking though is that I may be getting too rich and might start to foul plugs. Perhaps I should look into going smaller on the leak jet as well. I'm just not sure. I'm going to post on the Jetting forum as well...SC

Current Settings:
178 Main
45 Pilot
65 Starter
40 Leak Jet
80 PAJ
JD Red #4
Boyesen Quickshot ACV Cover
Fuel Screw: 0 Turns (No Response)
Temp: Mid 60's
Elevation: 5000'
Airbox: Snorkel-ectomy & Barnum's Airbox Kit

  • kincade

Posted April 10, 2005 - 07:32 PM



Be sure to post what your findings are; I have almost the exact same combination, and I just ordered the barnums kit too!

  • ncmountainman

Posted April 11, 2005 - 06:37 AM


try a 48 pj and a 100 paj before going up on the main, there seems to be some difficulty finding the correct 100paj. indy_wr450 has the part #'s on record :naughty:

  • clark4131

Posted April 11, 2005 - 08:35 AM


I thought about upping the Pilot Jet, but I'm already getting no response from the Fuel Screw. Wouldn't a larger pilot make matters worse?...SC

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  • ncmountainman

Posted April 11, 2005 - 08:52 AM


well i know 178 main is kinda extreme,i'm running a 170 on 4th clip with a yz airbox and intake. and find it about right(and thats with the powercore 4,the Q is alot more restrictive). at that alt its gotta be rich maybe so rich its overlapping the pilot circuit?

  • Dan_Lorenze

Posted April 11, 2005 - 09:18 AM


Man... a 178 main?

  • clark4131

Posted April 11, 2005 - 12:19 PM


As a baseline, I decided to go back to my last known good setting prior to the addition of the Barnum's kit , 170 Main, JD Red #4, #40 Leak, all the rest stock. It ran better and my bog was much less. I decided to bump the Main up to 172 and keep everything else the same. That improved the bog to virtually nothing and 3rd gear roll-on wheelies, so I'm happy with it. I've got a #100 PAJ coming, so I'll give that a shot and hopefully I'll get some fuel screw adjustability back. I have a little with the 170 and 172, but anything after 3/4 turn is the same and all the way in just creates a little stumble. I know with a 168 I am pretty lean as everything gets very hot, enough to melt the metallic sticker off the Q2 pipe. I think with the increased airflow, the larger PAJ is the way to go. Fingers crossed...SC

  • mtrablue

Posted April 11, 2005 - 06:04 PM


try the 48 pilot.


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