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Jetting/ idle problem


straddlez

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Having a problem with my banshee idling. If I have to choke all the way out the bike idles fine but as soon as I put the choke in the bike revs up maybe somewhere around half throttle but as soon as I pull the choke back out it goes back down to idle. I have sprayed everything down with carb cleaner multiple times to make sure I don’t have an air leak which I don’t. My idle screws are only in a turn and a half. Should I mess with the air screw? Seems like I have a lot more smoke than normal coming out of the exhaust. I have a 270 main jet in it and I’m not sure about the pilot I can find out later tonight. Do I need a bigger pilot jet or move the spot on my needle I’m not sure. The mods I have are stock air box with pro design air filter and no lid, v force 4 reeds and fmf exhaust and stock mikuni carbs.

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I've seen lean running engines rev up on their own. Turn your air screws all the way in and back out 1-1.5 see if it runs better (can even go .5). Depending on weather extremes might even have to change jetting). If not, clean your carbs and check your bowl height. If still nothing change pilot. Just doesn't make sense assuming it ran before with those pilots. I'd check the airscrew and cleanup carbs first.

Sent from my SM-S908U using Tapatalk

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I've seen lean running engines rev up on their own. Turn your air screws all the way in and back out 1-1.5 see if it runs better (can even go .5). Depending on weather extremes might even have to change jetting). If not, clean your carbs and check your bowl height. If still nothing change pilot. Just doesn't make sense assuming it ran before with those pilots. I'd check the airscrew and cleanup carbs first.

Sent from my SM-S908U using Tapatalk


*to change pilot

Sent from my SM-S908U using Tapatalk

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11 minutes ago, pk31337 said:

I've seen lean running engines rev up on their own. Turn your air screws all the way in and back out 1-1.5 see if it runs better (can even go .5). Depending on weather extremes might even have to change jetting). If not, clean your carbs and check your bowl height. If still nothing change pilot. Just doesn't make sense assuming it ran before with those pilots. I'd check the airscrew and cleanup carbs first.

Sent from my SM-S908U using Tapatalk
 

I did already clean the carbs and that’s why I didn’t think it was the pilot jet I never had a problem in the past. I will adjust my idle screws thank you hopefully it work.

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Go on Google and type “leak down tester bansheehq”

the first link will send you here to a write up on how to build the tool to do it. It will cost around $25-30 or so…. But it will be an invaluable tool that you should use just after assembling a banshee motor or before disassembling after a failure. 
 

there are parts of these motors that you can’t get spray to like you did looking for an air leak. 
 

the key for doing these tests is to pressurize the engine to 6psi (no more or you’ll push seals out) and watch your pressure to see if it drops. What you NEED is for the engine to drop NO LESS than 1psi per minute. If it drops faster than that, you will be creating a lean condition and can have a lean runaway like you are experiencing. 
 

Dish soap mixed in with water will show you where the motor is leaking…..

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