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Main Area => General GS500 Discussion => Topic started by: Merkurio24 on November 22, 2006, 04:28:53 PM

Title: Clean Carburators and New Backfires!!
Post by: Merkurio24 on November 22, 2006, 04:28:53 PM
 My bike was firering in one cylinder so  I did the following and now is working fine/with other problems:

I just had my carburators cleanned today at my local dealer. I have also intalled them and have two concerns. The first one is that I cannot get the idle at 1200rpm, in fact I cannot get it lower than 2500rpm. Every time I open the throtle, the rpm stays up! :dunno_white: Is there any way to set this right?

The second problem is  that as soon as I was done istalling the carburators and everything else, I started the bike and it did start rightaway. After about 30 seconds I heard a loud explosion which came from the exaust :o. Does anyone have an idea of what this could be?
Title: Re: Clean Carburators and New Backfires!!
Post by: NiceGuysFinishLast on November 22, 2006, 04:31:01 PM
Well.. the hanging idle = air leak somewhere, it's running lean. Check the rubber carb boots.

no idea bout the backfire though.
Title: Re: Clean Carburators and New Backfires!!
Post by: scratch on November 22, 2006, 04:34:26 PM
Is the choke stuck open?

Check the choke cables and linkages are clear.

Check that the throttle cable is not hanging up.

Check for airleaks around the airboots and carburetor mouths.
Title: Re: Clean Carburators and New Backfires!!
Post by: Merkurio24 on November 22, 2006, 04:46:23 PM
the temp is about 30 degrees f.  The choke cables are clear, I don't know what you mean by "thottle cable hanging".
Now about the airleaks on the boots, I think is a possibility.

QUESTION: Does the dealer set the idle srew on the carbs. at the factory setting or not? :icon_confused:
Title: Re: Clean Carburators and New Backfires!!
Post by: scratch on November 22, 2006, 04:49:06 PM
Idle should be set to 1300rpm when warm, by that, meaning the engine is a full operating temperature; usually after a good 15 minute ride.

Ride it to work and then set the idle when you get to work.
Title: Re: Clean Carburators and New Backfires!!
Post by: Merkurio24 on November 22, 2006, 04:56:20 PM
how do I adjust the idle? That is the problem I cannot! the adjusting knob under the carbs. does not make any affect to the idle :icon_confused:

QUESTION: Could the problem be a vacuum hose wrongfully routted?
Title: Re: Clean Carburators and New Backfires!!
Post by: scratch on November 22, 2006, 05:11:48 PM
Oh yeah.  It sounds like your best bet is to make sure the carbs are seated in the intake boots (the ones between the engine and the carbs).

And, then also make sure the airboots (the ones between the carbs and the airbox) are sealing all the way around the carb mouths.

And, now to address your "hanging throttle" question: I was asking if the throttle cable was moving freely, without binding up, or isn't pinched anywhere causing it to "hang open"; you want to hear is "snap" against the throttle stop down between the carbs.
Title: Re: Clean Carburators and New Backfires!!
Post by: scratch on November 22, 2006, 05:13:06 PM
Quote from: Merkurio24 on November 22, 2006, 04:56:20 PM
QUESTION: Could the problem be a vacuum hose wrongfully routted?
No, because then it wouldn't run at all (or only for a little bit).

Unless, you didn't hook up the vucuum hose from the carburetor to the frame-mounted fuel selector.
Title: Re: Clean Carburators and New Backfires!!
Post by: Merkurio24 on November 22, 2006, 05:20:48 PM
No, I think I got the routting right.

QUESTION: I notticed that the idle adjusting knob under the carburators, is not even touching the throttle lever. And when I try to use this knob for adjustment it does not work at all ( it does nothing) Is this normal or is there something wrong here?
Title: Re: Clean Carburators and New Backfires!!
Post by: Merkurio24 on November 22, 2006, 05:23:12 PM
Quote from: scratch on November 22, 2006, 05:11:48 PM
Oh yeah.  It sounds like your best bet is to make sure the carbs are seated in the intake boots (the ones between the engine and the carbs).

And, then also make sure the airboots (the ones between the carbs and the airbox) are sealing all the way around the carb mouths.

And, now to address your "hanging throttle" question: I was asking if the throttle cable was moving freely, without binding up, or isn't pinched anywhere causing it to "hang open"; you want to hear is "snap" against the throttle stop down between the carbs.

Can an airleak really affect the idle speed?
Title: Re: Clean Carburators and New Backfires!!
Post by: bettingpython on November 22, 2006, 06:40:24 PM
Yes! More air means leaner fuel/air mixture which means more oxygen and higher combustion temeratures and more power. To a certain point and beyond that point it becomes detrimental and leads to a loss of power excessive engine temperature and preignition of F/A mix when entering the cylinder, this can cause backfiring throught the carbs and could lead to cylinder wall damage and bent rods. Make sure all boot's attached to the carbs are sealed tightly.

With the engine off!!! Twist the throttle completey open. Let go of the throttle, it should quickly and smoothly rotate fully forward to the fully closed position. If you can roll the throttle forward from where it stops then need to check/adjust cable tension, check routing of your cables to be sure they are not pinched or kinked and lubricate them.

Make sure the choke is not partially engaged even though the lever is fully forward, do this by finding the rod and link on the right hand side of the carbs  that moves when you pull the choke lever back. When you take the choke off (push it forward), see if you can pull the linkage rod out further from the carb bodies. If so check for something pinching the housing between the handelbars and carb, if there is no binding lubricate the cable.

Do you have a manual? If not get one.
Title: Re: Clean Carburators and New Backfires!!
Post by: The Buddha on November 22, 2006, 06:46:21 PM
The Mofo's lost the damn O rings. Also rejet the mofo.
This is one reason why dealers shouldn;t get into working on sheite. That is best left to the owners. When ever I hear "professionally maintained by dealer" I cringe. I know stripped screw head, tore up jets, busted plastic parts and missing O rings are in my future.
Cool.
Srinath.
Title: Re: Clean Carburators and New Backfires!!
Post by: Mandres on November 22, 2006, 10:10:55 PM
Quote from: Merkurio24 on November 22, 2006, 05:20:48 PM
No, I think I got the routting right.

QUESTION: I notticed that the idle adjusting know under the carburators, is not even touching the throttle lever. And when I try to use this knob for adjustment it does not work at all ( it does nothing) Is this normal or is there something wrong here?

There's your problem.  You need to adjust the throttle cable so that the lever rests against the adjuster screw.  Search for the adjustment procedure, I think Kerry has illustrated the process with good pictures before.

Title: Re: Clean Carburators and New Backfires!!
Post by: Merkurio24 on November 23, 2006, 08:15:13 PM
I will try all the different sujestions on friday since it is going to be a nice day. Thank you to all who have replied to my questions!
Title: Re: Clean Carburators and New Backfires!!
Post by: Merkurio24 on November 24, 2006, 03:16:38 PM
Finally!!!

I got everything fixed!! I had to adjust the throttle cable on the carburator, and there was a leak betwin the air box and the carburators. I still want to replace the tubes that connect the airbox to the carbs. because one of them has a little slit. Anyway, I'll like to thank everyone who contributed in fixing my Gs problem. :)

I'm going riding right now! :thumb:
Title: Re: Clean Carburators and New Backfires!!
Post by: scratch on November 24, 2006, 03:19:49 PM
Awesome!  Congradualtions!  And, you're welcome!
Title: Re: Clean Carburators and New Backfires!!
Post by: The Buddha on November 24, 2006, 04:37:48 PM
Quote from: Merkurio24 on November 24, 2006, 03:16:38 PM
Finally!!!

I got everything fixed!! I had to adjust the throttle cable on the carburator, and there was a leak betwin the air box and the carburators. I still want to replace the tubes that connect the airbox to the carbs. because one of them has a little slit. Anyway, I'll like to thank everyone who contributed in fixing my Gs problem. :)

I'm going riding right now! :thumb:

Oh no ... it has a slit ... OK you need to find all that crap you cleaned out and cram it back in the carbs ... I mean ... you need to create a far bigger problem that you dont think of this as a problem ...
Cool.
Srinath.