Viper low end flutter

lsbufis

lsbufis

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Joined
Dec 14, 2012
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Canada
Has a bender 4x4 pipe and bender can, not sure if the fluttering sound is normal when you have a pipe/can while applying 1/8th or so of throttle? hard to describe lol so bare with me!!

carbs cleaned, needle was raised 1 notch by the dealer ( don't even think they did it right! ) and fuel screws are 2 turns out.. kinda sounds like a lil misfire maybe until u mash the throttle then she clears up...

any help would be appreciated.. also I've gone about 120km's to tank so far which I think is bad.
 
I think what you are hearing is sometimes referred to as a burble. This occurs when a small amount of unburnt fuel ignites in the pipe. This is normal and better then not having enough fuel. It is the smaller brother to what is commonly called a backfire.

I believe that many Vipers do this, but the stock can (suitcase) muffles it to where you can hardly hear it.

Why were your needles raised? Do you know the current needle position?
 
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They just told me they raise em one notch.. Guessing 4th setting..

Yes burble is the word.. Once u punch it it clears up.. Sometimes on idle itll kinda make a minor backfire and sounds like its running flooded under water.. Its on and off not constant..


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Yes, too much fuel at that rpm for the engine and tuned pipe to handle is what I think causes this. I am interested to know why they are raising the needles. Do they think the midrange is too lean?
 
The Viper is known to have a lean spot at cruise speed...raising the needle a tad is a safety measure for the lean condition.

Ding said:
Yes, too much fuel at that rpm for the engine and tuned pipe to handle is what I think causes this. I am interested to know why they are raising the needles. Do they think the midrange is too lean?
Click to expand...
 
Yes i had them raise the needle. Shoulda been more specific to u and the dealer..

Any clue about the idle noise i mentionned?


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tnc110 said:
The Viper is known to have a lean spot at cruise speed...raising the needle a tad is a safety measure for the lean condition.
Click to expand...

Yah, I have heard that many times before so it must be common. It just hasn't been my experience. Seems to be most common after sustained WOT and then running midrange throttle.

I was wondering what the reason was for this particular case.

Anyhow the burble can be reduced by turning the pilots back in, but then you have the high idle tendency.
 
The problem is without knowing exactly where the needles are set, its pretty hard to diagnose whats going on. usually a burble is from the needle setting.This is why it pays to learn how to do the work yourself, as you dont know what the setting is having a dealer do it or what they did there.

I dont have too much problem when switching to the normal 3.25 setting which is what I reccomend for ANY viper no matter how its run. Nothing to do with running it wide open then cruising it, anytime they are cruised right in the midrange they are lean, right from yamaha. High ign timing and higher compression in the mag and center cylinders coupled with lousy gas quality =detonation=blown pistons and cranks!

I see 2 posters here moved the needle by a whole spot. The needle setting for whats reccomemnded is moving the clip to the 4th groove down but BOTH of the plastic shims are to be on top of the clip, this provides the setting to be slightly richer then stock but no problem with burbling from being excessively rich.

best fix is to learn how to do the carb settings yourself and to confirm they are in the right spot, the burbling should then stop if they are set to 3.25.
 
I'm not sure on how to remove the needles to be honest..

Is the any write up with pics on how to? the carb cleaning 101 doesn;t show anything about needles and it mentions that you we're gonna create a how to :)

thx!
 
Mr Viper...are you saying that if it is burbling then the needle should be leaned? I moved my needle position by one shim and noticed it burbles quite a bit. Just got the sled at end of last year, and dont remember if it burbled or not before I moved the needle position.
 
tnc110 said:
Mr Viper...are you saying that if it is burbling then the needle should be leaned? I moved my needle position by one shim and noticed it burbles quite a bit. Just got the sled at end of last year, and dont remember if it burbled or not before I moved the needle position.
Click to expand...

stock the viper comes at #3 groove down with both shims under the clip, so if you moved only "the shim", you LEANED out the mixture, so you went the wrong way. You want the 4th groove down with both shims on top of the clip, this will be the 3.25 spot(this isnt in the repair manual)
 
mrviper700 said:
stock the viper comes at #3 groove down with both shims under the clip, so if you moved only "the shim", you LEANED out the mixture, so you went the wrong way. You want the 4th groove down with both shims on top of the clip, this will be the 3.25 spot(this isnt in the repair manual)
Click to expand...

I raised the needle one position...moved the clip to 4th groove and put shims on top. One position richer than it was when I got it.
 
tnc110 said:
I raised the needle one position...moved the clip to 4th groove and put shims on top. One position richer than it was when I got it.
Click to expand...

well... I am a bit skeptical of your statements because its exactly opposite of what you just posted, if you only went one spot on the clip richer then where it was before then youd be at 4 which would be too rich, and it would likely blubber there.....as the stock comes in groove 3 with both shims under the clip but then you claim you put the shims on top, which is it ? So, I am not sure where you are, because that would be the 3.25 setting and they dont burble there.
I can only go off what YOU post..... as I cant see the sled, or hear the sled so diagnosing a problem comes down to the persons description of what the symptoms are and/or the problem.
 
all I am saying is that I went the smallest increment that I could go in the direction to richen the mixture from where it was. I am at 3.25 and do have burble (unless it is something else I am hearing). Even my friend that has never really ridden before mentioned it.
 
tnc110 said:
all I am saying is that I went the smallest increment that I could go in the direction to richen the mixture from where it was. I am at 3.25 and do have burble (unless it is something else I am hearing). Even my friend that has never really ridden before mentioned it.
Click to expand...

about the only thing I can tell ya is put it back to stock then and see if you have the problem.
 
lsbufis said:
I'm not sure on how to remove the needles to be honest..

Is the any write up with pics on how to? the carb cleaning 101 doesn;t show anything about needles and it mentions that you we're gonna create a how to :)

thx!
Click to expand...

?? Anything


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lsbufis said:
?? Anything


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Click to expand...

for a beginner:

1.)remove carb rack from sled and place on bench.
2.)remove top of carb cover
3.)you will need a 2.5mm ballend allen wrench
4.)turning the throttle cam slightly insert the allen wrench down inside the slide and loosen up the 2 screws holing the slide to the linkage/arm
5.) turning the throttle cam slightly youll be able to slip the linkage off the pin/arm youll have to turn it at a slight angle to get it up and out of the slide.
6.) once its out reach your finger thru the back of carb and lift slide slightly, then gently push up on the needle it will slide up out of the slide.
7.) once its out you can put the clip wherever you need it, pay attention to the little plastic shims, theres 2 on each carb slide. sometimes thy stick to the peice with 2 screws in it so if you dont see them look on the bottom of that part.

reverse for assembly, take your time and dont force or bend that needle, youll need to manuver the slide up and down to get it to drop in and to get the linkage arm back on the pin, lift slide gently and retighten up the 2 small screws.
 
Excellent write up Don. For some pics there were instructions in the Tech Pages that should still be there. These pics might help visualize the process.

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Mrviper, Ding - thanks for the help I will carefully attempt this .. With bender can and pipe what should my fuel screws be set at in your opinion?? Currently At 2 turns and mileage sucks


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