KymcoForum.com
Scooters - Big Bore => Xciting 500 => Topic started by: guile on January 19, 2014, 04:19:17 PM
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Is it necessary to rejet a 500 Xciting carb (2006) with a third party exhaust?
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Yes, if it pops on deceleration? I would go up 1-2 main jet sizes at most. Leave everything else alone. Go 2 up if you put in a K&N style air filter like the DNA filter that is sold on ebay. :-*
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Thanks Sissy. The exhaust is not yet installed. Hopefully it doesn't pop!
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I installed the exhaust the other day. Great fun! Definately a bit more hp.
But it pops quite heavily when decelerating...
Sissy, could you direct me to the correct jets (on Ebay for instance)?
I have the stock airfilter installed.
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Main jet sizes depend on what country your bike was sent to? Europe is different from USA etc. It is a standard screw in jet. Remove and buy the next 2 sizes up. :-*
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Mine is European. Anyone knows what size(s) jet I need to buy?
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Almost all shops should stock them. Call a shop that sells them, remove your jet and buy 1 & or 2 sizes up. It sounds like u should go up 2, or even more? :-*
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What mm-size is standard and to what size does it need to be changed?
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If a kymco shop can not tell you? Then just pull it out and buy one about 2 sizes up. If it still pop's, go up 1 more until it stops. :-*
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You should also raise the 'needle' in the slide that affects 'mid-range.' "Raise=rich, Lower=lean."
Doing both the main jets and the slide is standard operating procedure for tuners.
You may be able to just go to the MFG's web-site and then either email customer service or call them and just ask them what size they recommend.
Sam:)
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Thanks for the advice!
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Guys, I really need to know what the standard jet size is of a Xciting (2006, carb). There is no Kymco in Holland
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FYI
standard jet size is supposed to be 108. I will get the jets as soon as possible and report back.
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Got the carb adjusted by a mechanic a couple of days ago.
It won't start now >:(
He said he adjusted the 'C0 screw'(?). It pops (sometimes even heavily!) when starting, but it won't start.
Can someone shine a light on this so I can fix it myself?
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He messed it up! Tell him to fix it FREE. At least have him set it back to stock. I never have a mechanic adjust my carbs. They only make it worse. Its easy to change a jet or raise a needle. Idiot should have left everything alone & just put in next size up main jet. I can't tell u what to do as I don't know what it is he really did or didn't do? :-*
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He messed it up! Tell him to fix it FREE. At least have him set it back to stock. I never have a mechanic adjust my carbs. They only make it worse. Its easy to change a jet or raise a needle. Idiot should have left everything alone & just put in next size up main jet. I can't tell u what to do as I don't know what it is he really did or didn't do? :-*
The only thing changed is the mixture-screw. I turned it back 360 degrees clockwise, but no real change.
I learned that starting it the way I used to by twisting the throttle does not work anymore. It floods the spark.
However, it does sometimes pick up when I don't twist the throttle. Not ideal, but better. any idea how that change came about?
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I never touch my throttle. Starts right up every time. Turn the key and do not hit the start button until the fuel pump stops clicking. This will prime the carb with gas. :-*
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Thanks Sissy, I will do that and hope it is the answer.
Strange though that it would never start before without twisting the throttle.
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Thanks Sissy. The exhaust is not yet installed. Hopefully it doesn't pop!
Because of the annoyingly loud popping of the exhaust I changed the main jet. The manual says the main jet is size 108. The Dutch Kymco Impoter said it is size 118. When I opened the carb it was indeed 118. I changed it to size 125. Less popping now, but still there. Should I go even higher now?
What size (approximately)?
Will this change fuel consumption?
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Sissy?
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If it still pops? I would say go up one more size? Pull the plug, if white it's lean. It should be light brown to tan. Dark brown/black/covered in oil, to rich. Make sure there are no leaks where carb connects to filter/breather housing, and where carb is clamped to where it go's to the head of motor. If these are not tight u could be sucking air, and this would cause bike to run lean and burn up engine/valves etc. I would make sure everything is tight/sealed good from manifold (round doughnut gasket), at header pipe, and all the way to where pipe clamps to muffler also. Make sure the manifold/gasket is tight where the intake mounts to the head also. Any leaks could cause this? :-*
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Thanks Sissy. I will go in and check all that.
Does changing the main jet size have any influence on fuel consumption?
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YES! Not enough to matter tho. 3-5 Km per tank maybe...
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Thanks zombie
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You're welcome.
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If it still pops? I would say go up one more size? Pull the plug, if white it's lean. It should be light brown to tan. Dark brown/black/covered in oil, to rich. Make sure there are no leaks where carb connects to filter/breather housing, and where carb is clamped to where it go's to the head of motor. If these are not tight u could be sucking air, and this would cause bike to run lean and burn up engine/valves etc. I would make sure everything is tight/sealed good from manifold (round doughnut gasket), at header pipe, and all the way to where pipe clamps to muffler also. Make sure the manifold/gasket is tight where the intake mounts to the head also. Any leaks could cause this? :-*
I put in a larger main jet, size #130. But it still pops very loud >:( The pops seem to be more muffled though, as if more on the inside of the muffler (closer to the engine?).
I checked for airleaks, but all is fine.
Should I go an even higher size main jet??
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Since it pops on deceleration and at low RPMs, you might do better to replace the pilot jet to a 40 from the stock 38.
The slow speed jet is running the engine until about 1/4 throttle, and that's where it pops.
I have a Leo Vince exhaust with a 40 pilot, and it popped too much with the 125 main jet, so I have a 120 main jet now. It still pops, but not as bad, and usually only one big pop after shutoff.
You can also tune the idle mixture screw to refine the low end, turn it clockwise until it stops, then back it out 2 1/2 turns and see how it performs, then you can go in or out accordingly. Out is rich, in is lean.
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There are two screws on the left side of the carb. The smaller one is the idle mix, and the larger one is the idle speed.
Turn the small mix screw all the way in till it lightly seats. Then back it out 2 turns. That should get you started. You may have to hold the throttle slightly open to keep it running. If that is the case turn the larger speed screw clockwise till the bike idles.
Once you get there turn the smaller mix screw in either direction. (slowly about 1/4 turn at a time).
The object is to increase the rpm w/ that small screw. If the idle falls, turn the other direction.
If the idle goes too high turn down the larger screw, and continue w/ the smaller screw till you get the best rpm.
If that small screw is closer to the engine intake it is a fuel adjustment, and needs to be turned 1/4 turn counter clockwise AFTER you have gotten the best rpm from it.
If it is on the air box side of the carb it is an air adjustment, and needs to be turned 1/4 turn clockwise AFTER the best rpm.
Both of those 1/4 turn settings will enrich the idle, and prevent lean stalls.
When you change your main jet you will not need to fiddle w/ this again as it only effects idle.
Show this post to your mechanic friend. It might help him make a better living, or at least keep a few friends around...
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Since it pops on deceleration and at low RPMs, you might do better to replace the pilot jet to a 40 from the stock 38.
The slow speed jet is running the engine until about 1/4 throttle, and that's where it pops.
I have a Leo Vince exhaust with a 40 pilot, and it popped too much with the 125 main jet, so I have a 120 main jet now. It still pops, but not as bad, and usually only one big pop after shutoff.
You can also tune the idle mixture screw to refine the low end, turn it clockwise until it stops, then back it out 2 1/2 turns and see how it performs, then you can go in or out accordingly. Out is rich, in is lean.
It does not pop at low rpm's, but it does pop on decelration after high rpm's.
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There are two screws on the left side of the carb. The smaller one is the idle mix, and the larger one is the idle speed.
Turn the small mix screw all the way in till it lightly seats. Then back it out 2 turns. That should get you started. You may have to hold the throttle slightly open to keep it running. If that is the case turn the larger speed screw clockwise till the bike idles.
Once you get there turn the smaller mix screw in either direction. (slowly about 1/4 turn at a time).
The object is to increase the rpm w/ that small screw. If the idle falls, turn the other direction.
If the idle goes too high turn down the larger screw, and continue w/ the smaller screw till you get the best rpm.
If that small screw is closer to the engine intake it is a fuel adjustment, and needs to be turned 1/4 turn counter clockwise AFTER you have gotten the best rpm from it.
If it is on the air box side of the carb it is an air adjustment, and needs to be turned 1/4 turn clockwise AFTER the best rpm.
Both of those 1/4 turn settings will enrich the idle, and prevent lean stalls.
When you change your main jet you will not need to fiddle w/ this again as it only effects idle.
Show this post to your mechanic friend. It might help him make a better living, or at least keep a few friends around...
Thanks zombie. Will this get rid of the popping? The engine runs fine there's only the the (annoyingly loud) popping sound.
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Listen to EVERY high performance engine built. They ALL pop when closing the throttle.
It's in the nature of the exhaust. Being more "free flow" in design it can not "muffle" this pop.
What is happening is there is always unburnt fuel in the pipe. (that's what cats are for). this fuel does ignite every time the exhaust opens. With an open pipe design you can here this fuel burning. A closed pipe masks the sound. That's all there is to it.
Old school chopper guys purposely run rich to amplify the effect.
You can minimize the pop by getting your combustion as close to perfect as possible but you will have to balance your jetting/needle height or injector duration/pulse width to gain perfect combustion across the rpm/load range.
Only experimenting will yeild results, and they will change with weather conditions, road conditions, and even to some degree the brand, and state of your engine oil.
Embrace the pop! Become one with your engine! I am your father Luke! 8)
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Listen to EVERY high performance engine built. They ALL pop when closing the throttle.
It's in the nature of the exhaust. Being more "free flow" in design it can not "muffle" this pop.
What is happening is there is always unburnt fuel in the pipe. (that's what cats are for). this fuel does ignite every time the exhaust opens. With an open pipe design you can here this fuel burning. A closed pipe masks the sound. That's all there is to it.
Old school chopper guys purposely run rich to amplify the effect.
You can minimize the pop by getting your combustion as close to perfect as possible but you will have to balance your jetting/needle height or injector duration/pulse width to gain perfect combustion across the rpm/load range.
Only experimenting will yeild results, and they will change with weather conditions, road conditions, and even to some degree the brand, and state of your engine oil.
Embrace the pop! Become one with your engine! I am your father Luke! 8)
Haha, I like your style Zombie. May the force be with you ..
I notice a little stalling at the end of the throttle. Could this be coming from the size #130 main jet (size #118 is stock)?
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It could be loading up w/ fuel. How does it run from 1/2 throttle up? How about idle, and slow acceleration?
If the low end is good (not going above 1/2 throttle) then the main might be too rich.
If you have any stumble at low rpm then the pilot may be too lean.
Sometimes you can compensate by adjusting the fuel mix screw to richen up the low end.
Changing the pipe effects both jets, and you might have to go up a jet or two on the pilot.
Jetting is a pain in the you know what. But when you get it right it is it's own reward.
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It could be loading up w/ fuel. How does it run from 1/2 throttle up? How about idle, and slow acceleration?
If the low end is good (not going above 1/2 throttle) then the main might be too rich.
If you have any stumble at low rpm then the pilot may be too lean.
Sometimes you can compensate by adjusting the fuel mix screw to richen up the low end.
Changing the pipe effects both jets, and you might have to go up a jet or two on the pilot.
Jetting is a pain in the you know what. But when you get it right it is it's own reward.
The low end is good, good pick up. It only stalls at high rpm; at the end of the trottle.
This means that I should lower the main jet in size then?
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That's a 50 /50 call. I'd get a set of jets ranging from 125-145. (steps of 5). Your slide needle should be adjustable as well.
The way to figure if you need more or less jet is to raise the needle (lower the clip), and see if it improves. If it does then you need more jet. If it is worse then lower the needle (raise the clip) to verify.
Even if one of these positions works GREAT, you still need to jet accordingly, and return the needle to the center clip position. Reason is you want to have a margin for adjustment either way to fine tune. You never want to be at the end of an adjustment. (especially if there are mobsters involved)
You're real close.
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Thanks zombie!
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Welcome you are...
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The Diaphragm has swollen and won't fit properly; it won't seat well. Any suggestions?
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That's from Ethanol
Let it sit in front of a blow drier (no heat) for 1/2 hr. It will shrink back as the Eth evaporates.
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Thanks zombie; worked great.
I settled with raising the needle and installing a main jet size #125. I notice a fairly big improvement in mid throttle.
The pops are still there, but the cows have to get used to them.
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I worked on a dairy farm as a kid. That should qualify my saying, f*** a bunch of cows!
Glad it's working out. You might find you will need a colder plug in the winter due to the thinner air. Depending on how close your jetting is to perfect, you might even want to try one hotter, and one colder now to dial it in further. Higher numbers are colder.
You have to love jetting. It sucks.
I really am happy for you. This makes my day, and it's only 8am
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We're lucky to have you on the forum :)
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It keeps me off your mom!
Sorry.
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It keeps me off your mom!
Sorry.
don't be
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Oh my god... I'm crying here.
You started my day w/ a smile, and ended it w/ tears... What a day!