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FCRMX Pilot Jetting Assistance

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great!!! i can't find my stock fuel screw :thumbsdn:

i did however, rejet the pilot jet to a 38 and changed to a MSR fuel screw instead. the fuel screw seems to have a much better influence on the bike when turned now. the initial test ride seems great... the bike stalled a couple of times after throttle blip so i turned out the fuel screw 1/4 turn and remedied that. seems to be running much better now.....i got my fingers crossed :devil:

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ok,any one having a rich pilot circuit issue shoudl do the following.

completely remove the pilot air jet.stay with the 45 pilot jet.set fuel screw as required.

something has obviuosly changed in the air passage of the pilto circuit.

why i dont know,but it has changed.

the 42-48 pilot jet and 100 pilot air jet is pretty a constant on all fcr carbs.

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Is the pilot air jet also called the "slow air jet" in the FCR parts diagram? Should we also lose the zipty screw and use the stocker?

Thanks :devil:

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wow that was fast! Thanks. I'll bolt up the FCR this weekend and try and fabricate a tool to adjust the stock fuel screw. Is there any difference between the zipty and MSR fuel screws?

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So we are completely removing a jet? Can you post a cut away and the number that we are supposed to remove? I just want to get this right the first, well in this case the 13th, time. Did we get a bad batch of carbs? Why do we have to do this and others don't? Can TT get us replacements? Alot of clams to shell out to have to jimmy rig somthing to make it work right (IMHO).

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it is the left jet under the intake bell.its marked 100.

the cabr is not bad.something has changed in the manufacturing process.

you guys need to understand i do not sell this kit.i do not make any money from the sales.

i am simply the guy trying to help with the jetting.

i dont work for TT or the store.

i remove pilot air jets all the time from modified crf carbs.its not a big deal and not jimmy rigged in my opinion.

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wow that was fast! Thanks. I'll bolt up the FCR this weekend and try and fabricate a tool to adjust the stock fuel screw. Is there any difference between the zipty and MSR fuel screws?

they are the same.

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Thanks guys!! Ed, if you say its not jimmy rigged then thats good enough for me. Do I now go back to your original recomendation for jetting? Has my ZIP-TY caused some thread gapping or anything that will cause my stock fuel screw not to seat correctly? Thanks for leading the charge in figureing this out :thumbsdn::devil:

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its up to you.your seems sorted so you can leave it.

remoivng the pilot air jet will save others from doing the pilot jet shuffle.

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its up to you.your seems sorted so you can leave it.

remoivng the pilot air jet will save others from doing the pilot jet shuffle.

Yeah just wanted to know if I'd gain anything by removing that and going back to your original recomendation. I still have a slight hesitation when going from wot, cutting, then going half throddle (fast)

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Sorry if this has been covered before, but i'm curious as to why the extended fuel screws, zipty, MSR are shorter than the stock screw (from top of threads to the tip)??? It seems, to me anyway, that if the extended screw will not fully seat you would have serious problems setting your idle mixture regardless of the size of the pilot jet. :devil:

Does the FCR-MX use a different screw that is longer than the previous 39mm carb? anyone......bueller?

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http://www.sudco.com/fcrmx.html

part number 30 on the diagram. they call it the "slow air jet"

Anyone know what part #29 is, and why its not listed? Is this the "leak jet" for the AP?

I noticed in other threads (Husky area)guys are playing with the AP squirt duration by changing the leak jet, amoung other things. They are fighting off throttle bog.

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Now we are getting somewhere....removing the 100 jet did the trick on my bike. The fuel screw now reacts properly and I went with a 42 Pilot Jet since I am using the ZipTy and a 155 Main Jet with totally stock exhaust.

THANKS SO MUCH EDDIE!!!!!!!!!!!!!!!!!

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Now we are getting somewhere....removing the 100 jet did the trick on my bike. The fuel screw now reacts properly and I went with a 42 Pilot Jet since I am using the ZipTy and a 155 Main Jet with totally stock exhaust.

THANKS SO MUCH EDDIE!!!!!!!!!!!!!!!!!

what were eddies original recomendations? what did you start with and where are you now after removing the jet and keeping the zipty

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Ditto what lovematt said. I was having the FCR-MX bog issue that several others have had, and neither the original FCR-MX fuel screw, nor the aftermarket ZipTy fuel screw was having any effect.

So, using Ed's recommendations, I pulled the 100 pilot air jet out, and put in a 42 pilot jet since I'm using the ZipTy fuel screw. I have a stock exhaust, and the 155 main jet.

The results???? The bog is gone, and throttle response is instantaneous! The FCR-MX pulls HARD, and lofting the front wheel is too easy.

I'm thinking that this was all an elaborate ruse to give us repeated experience pulling, and replacing our carbs! Seriously.... trying the different jets was educational and worth the time and effort. Thanks Eddie!

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I started with a 160 MJ and 45 PJ with stock fuel screw at 2 turns out. Had a lot of burbling and some bogging off idle. Overall acceleration was good.

I then went to 155 MJ and 42 PJ with ZipTy at 2 turns out...burbling was still there but not nearly as problematic and bogging off idle went away. However got some surging at 2000-5000 light load steady throttle. Overall acceleration was good.

I then switched to a 40 PJ and left the ZipTy at 2 turns out...burbling pretty much gone but surging got a little worse. Overall acceleration was good.

This morning I removed the 100 jet, kept the 155 MJ, and put the 42 PJ back in. When ZipTy is fully seated the bike wants to die...when a little over two turns out the idle is fastest. Still accelerates good, surging is completely gone, and I now need the choke to start when cold for a few seconds. Before I didn't need the choke in the morning...I am extremely happy with the way the bike is running now so I will leave it this way for a while.

2006 DRZ400SM with totally stock exhaust and 3X3 mod through all of the above.

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