Fuel flow?

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Jul 18, 2006 | 06:36 AM

Sally88

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Fuel flow?

My XL 1200 idles fine. When I crack open the throttle it chugs and tries to die. If I open the throttle REALY slow it is ok. I re jetted 2 weeks ago, and it ran awsome. I only changed the main jet to a 175 and pilot to 45, then 2 turns out on mixture screw. I never touched the top of the carb. I have taken the carb apart 3 times and everything looks ok, no obstruction. All vaccum lines ok, the one on the petcock too. The accelarotor pump is spraying, and the primer jet is ok. The choke is also ok, not stuck open. I had the tank off before this problem and set it in the grass. I found some debris in the petcock where it plugs into the hose that goes to the carb. I blew pretty hard in the petcock to make sure it was clear. Is there any chance a damaged petcock could cause the bike to idle fine then chug and stall under throttle? All help is appreciated!

Sally

Jul 19, 2006 | 12:01 PM

Spectrexx

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RE: Fuel flow?

Quote:

ORIGINAL: Sally88

My XL 1200 idles fine. When I crack open the throttle it chugs and tries to die. If I open the throttle REALY slow it is ok. I re jetted 2 weeks ago, and it ran awsome. I only changed the main jet to a 175 and pilot to 45, then 2 turns out on mixture screw. I never touched the top of the carb. I have taken the carb apart 3 times and everything looks ok, no obstruction. All vaccum lines ok, the one on the petcock too. The accelarotor pump is spraying, and the primer jet is ok. The choke is also ok, not stuck open. I had the tank off before this problem and set it in the grass. I found some debris in the petcock where it plugs into the hose that goes to the carb. I blew pretty hard in the petcock to make sure it was clear. Is there any chance a damaged petcock could cause the bike to idle fine then chug and stall under throttle? All help is appreciated!

Sally

Could be a plugged filter or malfunctioning petcock, but I'd check some other things first. Is the accel pump adjusted properly (as per the factory manual)? Are there any intake manifold leaks? Try removing the gas cap and see if that helps. It might not be venting properly. It wouldn't hurt to put it on a dyno for a tune up. That's the only way to get the carb set perfectly for all RPM ranges.

Let us know what you find. Good luck!

Jul 20, 2006 | 01:15 AM

Sally88

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RE: Fuel flow?

It was the plugs. They were black. I had the idle mixture screw 2 1/2 turns out. May have been too rich, I went back to two turns out.

Jul 20, 2006 | 11:36 AM

Spectrexx

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RE: Fuel flow?

That'll do it! Good job!

You might also try to keep your choke use to a minimum. They will foul plugs very quickly if overused.

Jul 20, 2006 | 05:11 PM

Sally88

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RE: Fuel flow?

I got the carb spring in, but now after I start it, it leaks fuel from the bottom of the carb. It still wants to die when I give it throttle. Not sure if maybe I put the needle holder in upside down? I'm pretty sure the diaphram is ok, when I blow into the side the slide goes up. Maybe I'll turn the needle holder the other way and see what happens. A description of which way it goes would be appreciated.

thanks,
Sally

Jul 21, 2006 | 12:07 PM

Spectrexx

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RE: Fuel flow?

Sounds like you need a carb rebuild kit. That will show you how everything goes together. Then a good dyno tune is in order. That's the only way to get the jetting right on. Sorry I can't help with the needle installation.... over the years I've decided that the only carb I will ever use is the S&S Super. Simple design, easy to tune, and very reliable. It'll also work well on any build, no matter how powerful.

Jul 31, 2006 | 09:58 AM

FASTFXD

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RE: Fuel flow?

Sally,

I'm not sure frlom your post if you subsequently went into the top of the carb - but, sounds to me like you might have the needle installed incorrectly and it's not seating into the jet far enough down. When you crack the throttle, you're flooding it. Get a diagram of your carb and check to see you've got the parts in correctly.