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jetting with fatties


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When mine was stock I couldn't get the needle rich enough, it would always cough in the mid range. I went with the Dyno Jet jet kit. Stuck the 290 mains in, stock pilot, needle one clip from bottom. Jetting was perfect after that. The best it ever ran when it was stock....My elevation is around 1500ft above sea level.

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well, i dont know where you guys are getting this from but hears my jetting. i just got a 2-1 carb that i need to jet.

 

my old setup was. fmf fattys power core 2, stock air box with snokle, and yama lube 2R. oh and mine was bored .25mm over

 

i had 30 pilots but i would have ran 25 or 27.5 if i know that 30's were in there. and a 260 pilot. thats what jets i beleive come with the pipe for a banshee unless you have other things like advanced timming and more compression.

 

so what i wouild try before anything else is

 

25 pilot

260 mains

500-1500 above sea level

needle clip in the middle.(stock location)

 

 

maybe try a 27.5 pilot if its a lil lean

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That's what YOU ran, but that's not necessarily where everyone should be and I'd much rather be at 300 and rich than 260 and lean. In fact, that's about the leanest jets I've heard of running Fatties.

 

It's also very easy to confuse lean with perfect because a lean machine can often seem like it's running great, especially if your not familiar with what to look for. However, if your a little on the rich side, it might sputter some and you'll know what's up.

 

More or less, you can tell with this thread, every machine runs different and all we can give you is an "area" to start at, and you'll have to dial her on in based on your readings. It is much better to start out richer rather than leaner, because you have no chance of damaging the motor with a rich condition.

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according to the FMF website, they say with just pies added (Fattys)

30 pilot, stock needle, 260 Main Jet, but if you have an open airbox, 30-32.5 pilots, 280-300 Main jet,based on their suggestions, I can only guess they "pad" it a little bit, so as you will run a little fat, due to different machines running a little different from each other, and to allow zero liability, for motor damage, I would maybe start with 30 pilots, and 300 mains, and see how that goes? but if you have the lid on your airbox, I would probably think you are closer to 280 mains....stock pilots....

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according to the FMF website, they say with  just pies added (Fattys)

30 pilot, stock needle, 260 Main Jet,

I would NEVER just jet based off of what the mfg. says. They give a very general jetting for a guide, but 90% of the time it's not where it should be. I ran 310 to 320 main jets in my banshee with the lid on but the back 2 inches was cut off, 300 to 310 with the full lid. Also, Fatties don't generally like a pilot richer than 30. 25 or 27.5 should do it. If I would have taken the mfg. suggestions and kept them there, I'm sure I would have blown a piston. They have no clue what else you have. Also, as Banchetta has proven. You can take the same machine, with pipes, reeds, etc. and go from the east coast to the west coast, same elevation and have a 2 or 3 size jetting change, so there is alot more to it than just elevation also. If you have no clue where to start, using the mfg. as a suggested baseline is ok, i guess, but always run plug checks and richen if ever in doubt. In fact, if I was clueless, I'd take the mfg suggestions and add 2 or 3 more sizes to it before I ever put it in my machine. All in all, 90% of the time, the manufacturers are clueless.

 

slowpokebanshee, that's not directed at you, i just wanted to clarify my opinion on this. i meant to earlier and forgot, and your comment reminded me.

Edited by sredish
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I went with fmfs jetting on my shee with fatties and it was right on. 30pilot, 260main with air box on at about sea level nothing else really done to the bike. I just add a proflow kit with a foam filter/no air box lid and went up to 290 mains thinking that would wourk but its way to rich. I rode it a Pismo the other week and could not even get it into 4th gear going up any sort of incline because it would not get on the pipe, but on flat terrain it was better. I pulled the plug and it was very wet so I am thinking I need to drop down to maybe a 270 possibly a 280 and maybe going back to the stock pilot jet.

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Sredish is right. These are only baselines. No one can tell you exactly what your final results will be...You are better to start rich and work down. Big deal if you have to change the jets to lean it out. At least you won't be changing pistons... :o As far as listening to the manufacturers specs..... :lol::rotflmao::yank:

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Well I am getting confused. The only way I coulg get it to run right was with a 20 pilot, 1.25 turns on the air screws and a 290 main with the needle in the 4th clip from the blunt end. Does that 20 pilot sound right to anyone.

No, definitely does not. You should be 25 or even 27.5. The 290 and 4th clip sounds about right with the airbox lid on. Your pilot though, is definitely not right.

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