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Rejetting A Friends Banshee


jEsTer

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Need a good baseline for rejetting my buddys Banshee. As far as I know it is stock bore (friend just bought the thing and knows nothing about it...), stock reeds, but has FMF's with PowerCore II silencers, no snorkel, no air box lid, and a K&N with dust boot. It is running b8es plugs, and currently has 310 mains, 40 pilots, and middle clip... Now does this sound right for 0-2000 So Cal elevations?

 

Or would it be better to be running more like 340 mains, and 30 pilots, and middle clip?

 

Any help would be appreciated, I wanna try and go get the jets today...

 

Thanks,

 

-Brad-

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Thats weird, I've never heard of any body running #40 pilots but 310 mains would probably be right with #40 pilots. Most people end up with 27.5 or 30 pilots if they know what they are doing and tune the idle correctly. FMF's work good with #30 pilots. In your case I'd go #30 pilots, about 2 turns out on the air screws, middle clip on the needle, 320 or 330 mains. Do a plug chop to check cause the mains might need to be larger if it has porting or ignition advance. Does it not run good now or why do you want to rejet? It could have some sort of porting if it idles good with #40 pilots.

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Right now it doesn't idle welll, has off idle bog, and is basically just a pain in the a$$... I don't know too much about about Banshees being a two wheeler, but he figures since I can wrench on my 500, I can fix all his problems with no info... And I don't really feel like tearing his motor down to find out what all has been done (even though I probably end up doing that). I just wanted to try and get a good baseline on the jetting to start tweaking from...

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Stock pilots are #25 on all years. A stock #25 pilot and 340 mains would probably be flowing the same amount of fuel on the top end as a #30 pilot and a 320 or 330 main. If you have an off Idle bog then you probably have the stock ports are jetted real rich on the pilot with the #40. How you tune for the pilot if your rich is to turn the air screws out = make the air fuel mix leaner at idle. When you get beyond 2.5 turns out then you need to go down to the next size pilot. If it runs better the more you turn it in and you are at 1/2 turn out or less then go up a size. I would recommend you go down to a #30 pilot and a 330 main, needle middle clip, and start with the air screws at 2 turns out. Play with the air screws a little to see if it runs better if you turn them in a 1/2 turn to 1 1/2 turns. You can use the air screw to tune the idle and probably make 25, 27.5 and 30 pilots all work, I just think the best low end power and off throtle response is with the biggest pilot that will come in tune on the idle within 1/2 to 2 1/2 turns out on the air screws and the instructions that come with FMF's recommend a #30 pilot.

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Don't forget about the needle. The needle is what brings the two together and probably the second most important thing, next to the main jet. The needle will have more effect on the main than the pilot. One click on the needle is about .5 to 1 jet size on the main.

 

I'd have it in the 3rd or even 4th clip from the top/blunt end. After that, adjust your pilot to idle good and have good idle/off idle response.

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Well I got into the carbs again today to start dialing in the jetting, and the nut on the airscrew is stripped, so I can't adjust how many turns out!!! He has the twist throttle kit on it, so I think the airscrews are aftermarket, right? So where do I get new ones, or should I just roll the friggin thing out of my garage on trash day...

 

Sorry dealing with someone elses crap always makes me tense... :angry:

 

Also I really need to thank you guys for all your help and information, bansheehq.com really does kick ass... :D If only there was a comparable site for CR500's, all the ones out there I have seen are pretty lame... :(

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The air screws should stay the same with a twist throttle and or TORS removed and they should be a standard slotted screw not a bolt with a hex top. They turn very easy so I can't immagine stripping one unless you try to screw it in too hard after it is seated which isn't good to do either. Take a look at this Jetting FAQ it will show you a picture of the air screw, and its location. Make sure that you are turnign the right screw. If the air screw has been replaced with some sort of weird hardware store crappy jalappy screw then I would try to get new ones from a dealer. I think there is a website that will sell any part of the carb that you need and jets which will probably be cheaper and faster than a dealer but I cant remember what the site is and I never book marked it. Someone on here knows which site I'm talking about.

 

Jetting FAQ

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I think there is a website that will sell any part of the carb that you need and jets which will probably be cheaper and faster than a dealer but I cant remember what the site is and I never book marked it.  Someone on here knows which site I'm talking about.

CarbParts.com comes to mind. I generally call them and discuss what I need with them. They have all you need for carbs. I think Big Blue originally turned to them.

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My bad, I actually meant to say IDLE SCREW... Sorry... So are the idle screws standard? Because once removed, you can see where the guy grinded down the opening...

 

And almost every nut, bolt, and screw on this Banshee are hammered... The guy who owned this before must have known nothing about maintenance...

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