Im perplexed with carb issue
08-11-2009, 06:52 PM
#1
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Im perplexed with carb issue
SO over the last two weeks or so my carbs have been acting up... farting and surging/stumbling from idle to about 4k. Pulling the choke does nothing really.
As a little background, it has Wileyco pipes and stock jetting. for about 4 months it ran great, no carb farts, no stumbling/surging.
Out of the blue it started to have issues. I tried different gas companies, no luck.
I am perplexed, waht would cause it to suddenly have these carb issues? Also do you think a needle shim would help?
I started to screw with the jetting several months ago, but gave up as I could not get it to run right with any setting!!!
Any help would be great.
As a little background, it has Wileyco pipes and stock jetting. for about 4 months it ran great, no carb farts, no stumbling/surging.
Out of the blue it started to have issues. I tried different gas companies, no luck.
I am perplexed, waht would cause it to suddenly have these carb issues? Also do you think a needle shim would help?
I started to screw with the jetting several months ago, but gave up as I could not get it to run right with any setting!!!
Any help would be great.
08-11-2009, 10:29 PM
#5
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Join Date: Mar 2007
Location: Belgium, WI
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skoshere,
That sounds very much like a lean condition due to an air leak. This situation will get better as the rpms increase because the percentage of the unwanted air in the air entering the engine is decreasing (the throttle is flowing more, its just in comparison). It should be fairly easy to diagnose, as you won have to be moving at all. Prop your tank and spray some carb and choke cleaner around the carb boots, vent line lines, vacuum lines, and any other device that could be leaking unwanted air. If your PAIR system is still intact and operational, and it were to have a tear in the hose or be unhooked, this could also cause a lean low end. I am pretty sure this is what you should be chasing, as it "goes away" towards the top. There is also the distinct possibility that you could have a clogged pilot, but I would start with the easiest diagnosis first.
That sounds very much like a lean condition due to an air leak. This situation will get better as the rpms increase because the percentage of the unwanted air in the air entering the engine is decreasing (the throttle is flowing more, its just in comparison). It should be fairly easy to diagnose, as you won have to be moving at all. Prop your tank and spray some carb and choke cleaner around the carb boots, vent line lines, vacuum lines, and any other device that could be leaking unwanted air. If your PAIR system is still intact and operational, and it were to have a tear in the hose or be unhooked, this could also cause a lean low end. I am pretty sure this is what you should be chasing, as it "goes away" towards the top. There is also the distinct possibility that you could have a clogged pilot, but I would start with the easiest diagnosis first.
08-12-2009, 02:36 AM
#6
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Superhawks are as lean as practically possible from the start, add a pipe and you become leaner than allowable at least eating your performance gain.
White spark plugs will confirm this.
I would first get a dynojet kit and install it completely, including the small hole.
As for the why not before part of the equation, colder temperatures, altitude drop, air filter change are some of the many factors than can move the air/fuel ratio over the edge
White spark plugs will confirm this.
I would first get a dynojet kit and install it completely, including the small hole.
As for the why not before part of the equation, colder temperatures, altitude drop, air filter change are some of the many factors than can move the air/fuel ratio over the edge
08-12-2009, 04:11 AM
#7
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as for what I have done so far since last night... proped the tank and check the lines to the tank all correct. I will have to start testing for leaks. Nothing on the bike has changed and no elevation has changed either.
I will see what I can find.
I will see what I can find.
08-12-2009, 04:47 AM
#8
Ottawa, Ont.
Squid
Join Date: Apr 2009
Location: Ottawa, Ont.
Posts: 65
1) check and set the resistance coming from your TPS
2) use an OEM paper air filter
3) have a snoop around the bottom half of your airbox, looking for loose vel. stacks, plumbing as it should be, or anything out of place..
2) use an OEM paper air filter
3) have a snoop around the bottom half of your airbox, looking for loose vel. stacks, plumbing as it should be, or anything out of place..
08-12-2009, 08:04 AM
#10
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SuperBike
Join Date: Feb 2007
Location: Portland, Oregon
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SO over the last two weeks or so my carbs have been acting up... farting and surging/stumbling from idle to about 4k. Pulling the choke does nothing really.
As a little background, it has Wileyco pipes and stock jetting. for about 4 months it ran great, no carb farts, no stumbling/surging.
Out of the blue it started to have issues. I tried different gas companies, no luck.
I am perplexed, waht would cause it to suddenly have these carb issues? Also do you think a needle shim would help?
I started to screw with the jetting several months ago, but gave up as I could not get it to run right with any setting!!!
Any help would be great.
As a little background, it has Wileyco pipes and stock jetting. for about 4 months it ran great, no carb farts, no stumbling/surging.
Out of the blue it started to have issues. I tried different gas companies, no luck.
I am perplexed, waht would cause it to suddenly have these carb issues? Also do you think a needle shim would help?
I started to screw with the jetting several months ago, but gave up as I could not get it to run right with any setting!!!
Any help would be great.
' keeping it real '
it's difficult to diagnose over the web BUT it's made more difficult when we only have half the story. 4 statement about how your bike just started to act up ending in the 5th statement about how you messed with it and never got it to run right....
tim
08-12-2009, 08:18 AM
#11
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more like 4/5 the story... in a keeping it real statement... I went back to stock jetting.
basically tried jetting the carbs --> ran like **** --> went to stock --> ran great for a good amount of time -->over the last two weeks started running like ****. -->
symptoms of bike -
rough flucuating idle
carb farting on idle
stumble off idle
surging and feels like hunting for fuel up to 4k or so
after that it will clear up for the most part.
basically tried jetting the carbs --> ran like **** --> went to stock --> ran great for a good amount of time -->over the last two weeks started running like ****. -->
symptoms of bike -
rough flucuating idle
carb farting on idle
stumble off idle
surging and feels like hunting for fuel up to 4k or so
after that it will clear up for the most part.
08-13-2009, 07:02 AM
#12
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Join Date: Feb 2007
Location: Portland, Oregon
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more like 4/5 the story... in a keeping it real statement... I went back to stock jetting.
basically tried jetting the carbs --> ran like **** --> went to stock --> ran great for a good amount of time -->over the last two weeks started running like ****. -->
symptoms of bike -
rough flucuating idle
carb farting on idle
stumble off idle
surging and feels like hunting for fuel up to 4k or so
after that it will clear up for the most part.
basically tried jetting the carbs --> ran like **** --> went to stock --> ran great for a good amount of time -->over the last two weeks started running like ****. -->
symptoms of bike -
rough flucuating idle
carb farting on idle
stumble off idle
surging and feels like hunting for fuel up to 4k or so
after that it will clear up for the most part.
you get a rise in RPM's then you've found the leak.
have you removed the PAIR system ?
i'd may also be a debris problem. you might need to pull the idle
jets and check them.
what jetkit did you try ?
tim
08-13-2009, 07:58 AM
#14
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SuperSport
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Location: Victoriaville, Quebec, Canada
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Either a vac leak, but I guess you went trough this already.
I would check the carb diaphragms for a tear, or a bad seal, lean idle, clogged pilot, sticky slides.
How those plugs looks like there one white ?? if not we'll check something else.
Single cylinder misfire ?? Both carbs won't break at once
Have the cams been touched at all, CCT changed ??
This is a wide search, we need to narrow it as much as possible.
I would check the carb diaphragms for a tear, or a bad seal, lean idle, clogged pilot, sticky slides.
How those plugs looks like there one white ?? if not we'll check something else.
Single cylinder misfire ?? Both carbs won't break at once
Have the cams been touched at all, CCT changed ??
This is a wide search, we need to narrow it as much as possible.
08-13-2009, 08:08 AM
#15
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i am going to tear into it tonight and look for leaks...
i took the airbox off and the slides are not sticking.... it is a single cylinder misfire... i will also look at the plugs.
i took the airbox off and the slides are not sticking.... it is a single cylinder misfire... i will also look at the plugs.
08-13-2009, 09:17 AM
#18
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yeah i did remove the pair system.... I have the vent lines to the airbox still (from the cam cover) and I blocked off the airbox holes as i recall.
its been some time since I looked at it.
its been some time since I looked at it.
08-13-2009, 09:36 AM
#19
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Make sure the vacuum signal hose is plugged, that can be an air leak, other than that the ports of the reed valves on the cam covers need to be plugged, but mostly an exhaust popping problem since it dumps in the exhaust post past the exhaust valve.
08-13-2009, 05:20 PM
#23
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ok so far...
block off are still on ( on cam cover,air box, screw in small tube off front carb)
sprayed WD-40 on everything, didnt get much of anything on this.
carb boots are tight
idled good today, hung up slightly when reving around 3.5 - 4k
plugs were a light brownish, nothing to alarming
looking back on it the issue develops after about an hour of riding or so ( not sure that helps)
block off are still on ( on cam cover,air box, screw in small tube off front carb)
sprayed WD-40 on everything, didnt get much of anything on this.
carb boots are tight
idled good today, hung up slightly when reving around 3.5 - 4k
plugs were a light brownish, nothing to alarming
looking back on it the issue develops after about an hour of riding or so ( not sure that helps)
08-14-2009, 06:54 PM
#25
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MotoGP
Join Date: Aug 2006
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Mine started acting like that suddenly for some undetermined reason. I don't like to take the tank/carbs of anymore that I have to so I did a bunch of things at one time. First set the TPS at 500 ohms and i believe this was the culprit since it was way off. In fact there was not enough adjustment so I drilled a hole and put a screw in to get the correct setting. Once you mess with it a little, you can feel when the tension is right.
Anyway, I shimmed the needles .40, cut a slot in the air mixture screw and adjusted it out 2 and 1/4 turns (OEM jetting) courtesy of Hawkrider suggestions. Air filter: cut a piece of foam, soaked it in K&N oil and put air filter grease around the perimeter, and inserted it in place of the paper which I cut out leaving the screen; and cut the plastic flap down to filter level. Put it together and set the idling at 1300-1400 rpms. The result was phenomenal, Hawk ran better than ever all through the rpm range and still is. Didn't sync the carbs yet, but don't need to according to the way it runs. I have stock pipes with the rear baffle removed, so it is fairly equal to your slip-ons in terms of flow. Worked for me.
Anyway, I shimmed the needles .40, cut a slot in the air mixture screw and adjusted it out 2 and 1/4 turns (OEM jetting) courtesy of Hawkrider suggestions. Air filter: cut a piece of foam, soaked it in K&N oil and put air filter grease around the perimeter, and inserted it in place of the paper which I cut out leaving the screen; and cut the plastic flap down to filter level. Put it together and set the idling at 1300-1400 rpms. The result was phenomenal, Hawk ran better than ever all through the rpm range and still is. Didn't sync the carbs yet, but don't need to according to the way it runs. I have stock pipes with the rear baffle removed, so it is fairly equal to your slip-ons in terms of flow. Worked for me.
08-21-2009, 12:38 PM
#28
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so i shimmed the needles with 1 # 4 brass washer and looked at the TPS... I could not find any leaks any where.
removed it and connected some spade connectors... couldnt get a reading then when I did it was reading appx. 820... could not get it to move.... i suspect this is some of the cause as i had broken it ( a while ago) and repaired it, but i think the fix did not hold....
i got a new TPS on order and hopefully this should help.
removed it and connected some spade connectors... couldnt get a reading then when I did it was reading appx. 820... could not get it to move.... i suspect this is some of the cause as i had broken it ( a while ago) and repaired it, but i think the fix did not hold....
i got a new TPS on order and hopefully this should help.
08-22-2009, 10:54 AM
#29
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[QUOTE=skoshere;232110]so i shimmed the needles with 1 # 4 brass washer and looked at the TPS... I could not find any leaks any where.
removed it and connected some spade connectors... couldnt get a reading then when I did it was reading appx. 820... could not get it to move.... i suspect this is some of the cause as i had broken it ( a while ago) and repaired it, but i think the fix did not hold....
I guess not. Couldn't get it to move? You must have tried to move it without removing the rivets holding it? Don't forget the air mixture screw while you're in there. I had to work mine out with a modified treezer and then slotted it with a dremel cutting wheel.
hurry up, the weather is going to change!!!!!!!!!!
removed it and connected some spade connectors... couldnt get a reading then when I did it was reading appx. 820... could not get it to move.... i suspect this is some of the cause as i had broken it ( a while ago) and repaired it, but i think the fix did not hold....
I guess not. Couldn't get it to move? You must have tried to move it without removing the rivets holding it? Don't forget the air mixture screw while you're in there. I had to work mine out with a modified treezer and then slotted it with a dremel cutting wheel.
hurry up, the weather is going to change!!!!!!!!!!
