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Left in stuck in the trails


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For the record, Full FMF powerbomb q4 exhaust, 3x3, JD jet kit. Engine is otherwise stock. WHEN THE PROBLEM IS NOT HAPPENING, THE BIKE RUNS 100% PERFECT. NO JETTING ISSUES, DO NOT SAY JETTING ISSUES I WILL HIT YOU.

For some reason when i am riding and i hit a jump, big bump, log hop, ETC the bike will suddenly lose all throttle in the mid range. ANY throttle other than none will kill the bike. The only exception to this is if i get on the bike, and get it rolling in 2nd gear and then go WOT. That will bring the bike back and USUALLY make it okay again... That is until today. I couldn't get it to run correctly again today and i had to limp it back home. I suspect the needle is &%$#@!ed somehow.

THIS ALL STARTED HAPPENING AFTER I HIT A BIG JUMP BY ACCIDENT. I meant to roll up the hill to wheelie in 4th gear, but the "hill" turned out to be a jump. Stupid mistake but it happens. Right when i landed the bike would idle but have the same symptoms as above.

This A video i took today of what the problem is. 

 

Sorry if i come off like a total &%$#@!, but this problem has been plaguing me for months and im sick of it. I want to get an FCR carb but that won't happen until january when i have a bit more money. I'd love to get this resolved, Thanks!
 

Edited by k4f5x0r
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Your vid is not working. Anyways are you still running the vacuum style petcock?

It's working fine for me?  Yes stock petcock

 

Could be 'junk' or watery sludge moving around in the float bowl. Try draining if you are too lazy/busy to remove the bowl or carb for cleaning.

The carb is spotless as i got it new less than a year ago and 3k miles on the bike plus it's been continuously run all year. I rejetted it 2-3 months ago and it was spotless then as well.

UPDATE:

 

I took the top end of the carb apart and the boot/gasket/rubber thing was sitting in an upwards position, not in its normal sitting position. Forgot to snap a picture and not sure how to explain it.  But i put everything back together ensuring the needle moves and it's fine now.. So i'm thinking that rubber boot/gasket is torn somewhere. I couldn't find anything when i looked.

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UPDATE:

 

I took the top end of the carb apart and the boot/gasket/rubber thing was sitting in an upwards position, not in its normal sitting position. Forgot to snap a picture and not sure how to explain it.  But i put everything back together ensuring the needle moves and it's fine now.. So i'm thinking that rubber boot/gasket is torn somewhere. I couldn't find anything when i looked.

 

Are you trying to say the diaphragm was holding the slide up? So the slide couldn't return to the very bottom?

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Are you trying to say the diaphragm was holding the slide up? So the slide couldn't return to the very bottom?

Ah that's the word i couldnt remember LOL. The diaphragm was stuck upwards holding the slide higher than usual. I can't say if it was running like that since it moved back down without much effort, but who knows. I'll see what happens the next time i ride it. Still going to get an FCR in the future.

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Reason I asked about carb/fuel cleanliness is because water drops in the float bowl have been known to cause similar issues and it only takes a little in the tank to work their way into a spotless carb. The droplets don't pass through the main jet, just get in the way of the smooth flowing fuel, occasionally blocking the main.

BUT, it's just a shot in the dark.

Edited by shuswap1
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Ah that's the word i couldnt remember LOL. The diaphragm was stuck upwards holding the slide higher than usual. I can't say if it was running like that since it moved back down without much effort, but who knows. I'll see what happens the next time i ride it. Still going to get an FCR in the future.

 

 

Next time you have the carb in your hands see if the slide moves freely, or if you feel any rough spots. It could be the slide hanging up after the jump, though I've never heard of this happening before. It could also be that the diaphragm is old and not as flexible anymore, and the cold weather can make that even worse.

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The droplets don't pass through the main jet, just get in the way of the smooth flowing fuel, occasionally blocking the main.

Water will come up through the main jet but either either, you are right, water can cause the described symptoms.

1-200ml of methylated spirits to a tank of fuel will disperse any water in your fuel and cause no harm.

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Water will come up through the main jet but either either, you are right, water can cause the described symptoms.

1-200ml of methylated spirits to a tank of fuel will disperse any water in your fuel and cause no harm.

Not Canadian water!!

🙂

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Water in the carb doesn't make sense to me. It idles fine, goes WOT fine, it just won't operate on the needle correctly(when it's bumped?).

Pull the needle and insure smooth operation, inspect diaphragm.

Then check all electrical connections for poor contact, including the kill switch for contaminate.

All mystery problems are a process of elimination.

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Fixed! Not sure why it uploaded as private but i updated it to public. Hopefully that gives you guys an idea of &%$#@! is wrong  :banghead:

 

 

pull off your overflow hoses and make sure they're clear. 

check your diaphram

check your slide

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Glad you've fixed it.  Sounds like the needle was not seated properly and jammed the slide open.  As others have said, make sure the slide and needle move freely before final assembly.

 

edit: hold the diaphram against a bright light and look for holes (kinda doubt it).  If there's a tear, shoe goop will work, just a dab will do ya.

Edited by 38super
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Glad you've fixed it.  Sounds like the needle was not seated properly and jammed the slide open.  As others have said, make sure the slide and needle move freely before final assembly.

 

edit: hold the diaphram against a bright light and look for holes (kinda doubt it).  If there's a tear, shoe goop will work, just a dab will do ya.

 

Video is fixed :D

 

He's still gotta test ride it after the slide diaphragm refitting.

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