KymcoForum.com
General => Technical | How To => Topic started by: AgilityOnAnRV on May 01, 2012, 10:23:45 PM
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I'm working my way through some possible solutions to the surging issue that I've been having on my Agility 125 and I'd like to experiment with richening my air/fuel mix slightly. I replaced my fuel filter today and took off the seat well in doing so. I'm totally new to engine work and took a cursory glance at the carburator while it was visible, but I didn't see anything that looked to be the air/fuel mix screw. (I did find the idle set screw.)
Is it possible to access or see the air/fuel mixture screw on the carb by only pulling the seat well? How can I go about accessing the screw?
Thanks!
*I'm pretty sure that my language is more descriptive, but in saying "seat well" I'm referring to what the Kymco service manual call the "met in box."
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I dont really know, if the agility 125 is diffrent from the agility 50, when it comes to how the carburator is build, but with the 50-version, the screw is made of brass and placed on the left side of the carburator. Be carefull not to tighten it, as these screws have very fine threads and will be harmed if you are too harsh.
On the Agility 50, there are a hole on the left side of the scooter (when all shields and seat are on) right over the passenger foot support, and through this, you can access the mixture screw, if you have a long necked flat screwdriver. :)
But remember, that the mixture screw are only dominating when you are idling or at very little throttle. When giving more throttle, things like the shape and height of the needle are meaning more, and when at full throttle, its only the main jet, which are active. (Well not true, but the other parts are made for passing very little fuel at very low throttle, so the main jet is dominating) :)
On the picture below: the axis going left to right is how much throttle is given and the axis going up is the flow of fuel, compared to the flow of air.
Dark blue = mixture screw, light blue = idle jet, yellow = needle diameter, Orange = needle height, red = conic shape of the needle and white = main jet.
I don't know, if the design of your carburator is diffrent, but on the agility 50, the needle cant be adjusted, and it is only possible to fine tune at idle and Wide Open Throttle.
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You can get to it with a small tip "stubby " flat head screw driver. It is on the left side just below the intake manifold height. Maybe a small mirror will help you see it.
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I dont really know, if the agility 125 is diffrent from the agility 50, when it comes to how the carburator is build, but with the 50-version, the screw is made of brass and placed on the left side of the carburator. Be carefull not to tighten it, as these screws have very fine threads and will be harmed if you are too harsh.
On the Agility 50, there are a hole on the left side of the scooter (when all shields and seat are on) right over the passenger foot support, and through this, you can access the mixture screw, if you have a long necked flat screwdriver. :)
But remember, that the mixture screw are only dominating when you are idling or at very little throttle. When giving more throttle, things like the shape and height of the needle are meaning more, and when at full throttle, its only the main jet, which are active. (Well not true, but the other parts are made for passing very little fuel at very low throttle, so the main jet is dominating) :)
On the picture below: the axis going left to right is how much throttle is given and the axis going up is the flow of fuel, compared to the flow of air.
Dark blue = mixture screw, light blue = idle jet, yellow = needle diameter, Orange = needle height, red = conic shape of the needle and white = main jet.
I don't know, if the design of your carburator is diffrent, but on the agility 50, the needle cant be adjusted, and it is only possible to fine tune at idle and Wide Open Throttle.
Thank you, that's some seriously fantastic information. In light of what you said about the mixture screw, do you have any thoughts on what might be causing the surging that I've been experiencing? It only happens at WOT around or slightly above 50 MPH. It does not happen at WOT below that speed, and the scoot can maintain ~50 MPH without surging if I back slightly off of WOT.
Separately, I read something on another forum implying that changing the jet needle position might help. Thoughts?
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I don't think it is the idle mix screw. That is more of a Main jet/fuel filter/air filter problem. Do the basics... Plug/fuel/air filters. It could also be cvt issues (rollers) but I would start at the beginning. Add 2-3 oz's of sea foam to try to clean the jets too. Two -three tanks full with sea foam will get rid of most varnishes/sludge in the fuel bowl.
I have also seen fuel lines de laminate due to Ethanol in the fuel. I would.nt hurt to replace the fuel line with a Marine grade replacement.
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one more thing. Pull the cap off the top of the carb. The diaphragm inside should be near flat. If it is all wrinkly, and swollen it needs to be replaced
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And things just started to get weirder... I'm hoping that these two things are related, but in the last few of days the scooter has died twice while coming to a stop. Everything still feels great while riding around.
Is there a logical connection between the engine dying at stops and the surging at high speed / WOT?
As long as the thing keeps running while I figure this out, hopefully the troubleshooting will be enjoyable as a learning experience :-)
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And things just started to get weirder... I'm hoping that these two things are related, but in the last few of days the scooter has died twice while coming to a stop. Everything still feels great while riding around.
Is there a logical connection between the engine dying at stops and the surging at high speed / WOT?
As long as the thing keeps running while I figure this out, hopefully the troubleshooting will be enjoyable as a learning experience :-)
Troubleshooting are always the best learning experiences. ;)
I dont know how long time your scooter has been running, but if the air filter are dirty, you should replace it or clean it. You can partially clean it with pressured air or a powerful vacuum cleaner, but buying a new one is always the best. If this is the problem, your scooter will have been running richer and richer for some time. :)
If the carburator was adjusted to the proper mixture during the winter, when it was colder and the air was denser, then it will also be running rich now, where the air are becoming less dense, as we get closer to summer. :D
The next thing that comes into my mind, that can affect both idle and full throttle are weak spark (problably because of old spark plug) or a compression issue. :)
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Troubleshooting are always the best learning experiences. ;)
I dont know how long time your scooter has been running, but if the air filter are dirty, you should replace it or clean it. You can partially clean it with pressured air or a powerful vacuum cleaner, but buying a new one is always the best. If this is the problem, your scooter will have been running richer and richer for some time. :)
If the carburator was adjusted to the proper mixture during the winter, when it was colder and the air was denser, then it will also be running rich now, where the air are becoming less dense, as we get closer to summer. :D
The next thing that comes into my mind, that can affect both idle and full throttle are weak spark (problably because of old spark plug) or a compression issue. :)
Thanks! So...
Air Filter
The scooter is from 2008 and has ~3500 miles on it. I looked at the air filter last week and it seemed white and clean. Is a visual inspection enough to give it a thumbs up? According to the previous owner (a retired gentleman who didn't seem as though he would lie about this), the scooter hasn't been ridden through dirt / dust and was only really used for grocery trips.
Carb
I don't think that any adjustment was done last winter (the bike is in south Texas), although I thought that the issues that I'm experiencing would mean a lean mix, not rich? Am I wrong on that one?
Weak Spark
Okay, here's where I jump into scary waters. Is there an easy way for me to find my spark plug? How can I test this?
Compression Issue
To fully reveal my engine non- know-how... what does this mean?
Once again, huge thanks for your help! Figuring this out myself - with all of your help - is going to be immensely rewarding. I'll be checking out the carburator diaphragm today as time allows and I mixed Sea Foam in with the fuel yesterday.
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I didn't read the whole thread (bad manners, I know...) but for what it's worth, the Motion Pro tool has come in very handy for accessing hard to reach pilot adjustments:
http://www.motorcycle-superstore.com/2/9/205/4821/ITEM/Motion-Pro-Ninety-Degree-1-4-Hex-Driver.aspx?WT.ac=SLIsearch (http://www.motorcycle-superstore.com/2/9/205/4821/ITEM/Motion-Pro-Ninety-Degree-1-4-Hex-Driver.aspx?WT.ac=SLIsearch)
A dry-rotted intake manifold or cracked insulator gasket (plastic thing under the manifold) will cause whacky idling.
I'll go back and read the thread like a gentleman when I get a chance after work. :)
~Josh
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(http://)
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Juices pict is perfect. See the intake mount? That is where the carb attaches to the engine. Areomyst is right about the cracks there. They ALWAYS crack. You should replace the manifold, and the spacer under it with New parts, and O rings. Get ALL new filters, and a plug.
To test for weak spark there are tools but a simple 1/4" gap to any ground will tell the tale. http://www.partsforscooters.com/ (http://www.partsforscooters.com/) is a great place for these parts.
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Juices pict is perfect. See the intake mount? That is where the carb attaches to the engine. Areomyst is right about the cracks there. They ALWAYS crack. You should replace the manifold, and the spacer under it with New parts, and O rings. Get ALL new filters, and a plug.
To test for weak spark there are tools but a simple 1/4" gap to any ground will tell the tale. http://www.partsforscooters.com/ (http://www.partsforscooters.com/) is a great place for these parts.
I'm on a work trip now and hope to have an opportunity to match juice's photo up with the scooter tomorrow. Is the circled part in the photo the intake mount? Coming at this from having zero experience but wanting to experiment and learn:
-What will I need to remove to have access for examining and replacing the manifold and spacer? How can I know which manifold/spacer/O-rings to purchase? Are there any particular tools that I need?
-I assume that "get all new filters, and a plug" means new filters and a spark plug, but which filters are you referring to and is there any particular type of spark plug that I should get? Is it easy to pull the old plug and put in a new one? (And the ultimate beginner question... where is it?)
I hope that you can forgive my inexperience and keep sharing your knowledge!
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http://www.partsforscooters.com/151-9-INLET-PIPE-ASSY (http://www.partsforscooters.com/151-9-INLET-PIPE-ASSY)
http://www.partsforscooters.com/151-8-O-Ring?sc=9&category=465 (http://www.partsforscooters.com/151-8-O-Ring?sc=9&category=465)
http://www.partsforscooters.com/129-15-Universal-Fuel-Filter (http://www.partsforscooters.com/129-15-Universal-Fuel-Filter)
http://www.partsforscooters.com/129-15-Universal-Fuel-Filter (http://www.partsforscooters.com/129-15-Universal-Fuel-Filter)
http://www.partsforscooters.com/145-17_NGK_Spark_Plug (http://www.partsforscooters.com/145-17_NGK_Spark_Plug)
Before ordering do a compression test. http://shop.advanceautoparts.com/webapp/wcs/stores/servlet/product_x_9090005-P_x_x?cm_mmc=CSE-_-Google-_-VALUE3-_-VALUE4&ci_src=14110944&ci_sku=#utm_source=cse&utm_medium=google&utm_campaign=value3&utm_content=value4 (http://shop.advanceautoparts.com/webapp/wcs/stores/servlet/product_x_9090005-P_x_x?cm_mmc=CSE-_-Google-_-VALUE3-_-VALUE4&ci_src=14110944&ci_sku=#utm_source=cse&utm_medium=google&utm_campaign=value3&utm_content=value4)
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http://www.partsforscooters.com/Foam_airfilter_qmb139 (http://www.partsforscooters.com/Foam_airfilter_qmb139)
I put the wrong link in the other post
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[...]
Air Filter
The scooter is from 2008 and has ~3500 miles on it. I looked at the air filter last week and it seemed white and clean. Is a visual inspection enough to give it a thumbs up? According to the previous owner (a retired gentleman who didn't seem as though he would lie about this), the scooter hasn't been ridden through dirt / dust and was only really used for grocery trips.
[...]
As the other guys have provided good information about the other possible issues, i will concentrate on the filter. :)
You say white, and this throws me off, as the filter on the agility 50 is orange. Can you see, if the filter is like papery fibers, or like a sponge?
If it is made of paper fibers, dont get it wet, but vacuum clean it or blow high pressure air through it, but if it is sponge, then blow air though it (as your vacuum cleaner might not like the oil), and then pour a little oil on the filter. Then you should press the sponge-filter, so only a little oil is left there. :)
I dont know about the diffrences of the agility 125 and the agility 50, but in my service book, it sais that the air filter should be cleaned every 1000 km and replaced every 2000 km, even though this is not necersary most of the time. :D
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Today involved an oil change along with examining the carb diaphragm and vacuum hoses. The air filter will certainly be next. Filling up the gas tank today for round two of Sea Foam.
Results:
-The oil was pretty gnarly. Oil change complete. (I just purchased the scooter. The previous owner's records have an oil change noted at 2300km and I'm at 5600km now.)
-The carb diaphragm looks good, although I have no real reference point. See photo linked below. Am I right?
-Possible issue: There is a slight gap where the carb meets the engine. (Sorry for the complete lack of technical terms...) See photo linked below. Is this supposed to be there?
Carb diaphragm: http://tinyurl.com/carbdiaphragm (http://tinyurl.com/carbdiaphragm)
Full view from above: http://tinyurl.com/8y4bykp (http://tinyurl.com/8y4bykp)
Carb close-up: http://tinyurl.com/carbclose (http://tinyurl.com/carbclose)
The gap: http://tinyurl.com/carbgap (http://tinyurl.com/carbgap)
I'd also like to take a look at the spark plug. I'm pretty sure that I located it, but how do I remove the plug?
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Today involved an oil change along with examining the carb diaphragm and vacuum hoses. The air filter will certainly be next. Filling up the gas tank today for round two of Sea Foam.
Results:
-The oil was pretty gnarly. Oil change complete. (I just purchased the scooter. The previous owner's records have an oil change noted at 2300km and I'm at 5600km now.)
-The carb diaphragm looks good, although I have no real reference point. See photo linked below. Am I right?
-Possible issue: There is a slight gap where the carb meets the engine. (Sorry for the complete lack of technical terms...) See photo linked below. Is this supposed to be there?
Carb diaphragm: http://tinyurl.com/carbdiaphragm (http://tinyurl.com/carbdiaphragm)
Full view from above: http://tinyurl.com/8y4bykp (http://tinyurl.com/8y4bykp)
Carb close-up: http://tinyurl.com/carbclose (http://tinyurl.com/carbclose)
The gap: http://tinyurl.com/carbgap (http://tinyurl.com/carbgap)
I'd also like to take a look at the spark plug. I'm pretty sure that I located it, but how do I remove the plug?
That's a gab between the black "dress" (translation from danish, dunno what its called in english) and the intake manifold. The dress has the purpose of guiding the cooling air around the engine, and it is in the end directed out onto the exhaust. :)
The engine is made of metal and is underneath the "dress". :)
If there are a gab between the manifold and the engine, your engine will get what we call "false air", which is air which havent had fuel added to it. This will give a lag when you give more throttle, and will eventually cause your engine to be running lean. To check if there is a gab here, get some start spray and spray around the intake manifold while idling. If you are getting false air, the start spray will be sucked into the engine and will raise the rpm. :)
Often there are no gab here, but sometimes there can be little cracks in the intake manifold, so if the rpm rise when you spray at this, then it should be changed or fixed. (The right way is to change the manifold, and the wrong way is to make LEGO-glue, by mixing 1 2x2 Lego with acetone, as seen in this post: http://www.billig-scooter.dk/showthread.php?tid=14619 (http://www.billig-scooter.dk/showthread.php?tid=14619))
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YUP!!! Your diaphragm is SHOT. When new they are almost flat. (no wrinkles). Also when I zoomed the manifold it appears the tightening screw is digging into the rubber, and that will create an air leak as posted by Baddi. Rather than fix/replace the manifold I burn off the rubber, and replace the carb using a fuel proof rubber coupler. Just a simple rubber hose cut to length, and two hose clamps. You can get new O rings at the auto parts store for a few cents to replace the one under the manifold. Or just get a new manifold from http://www.partsforscooters.com/Welcome?search=intake+manifold+125 (http://www.partsforscooters.com/Welcome?search=intake+manifold+125)
For the spark plug I think a 5/8" socket with a 6" extension will get it.
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and replace the carb using a fuel proof rubber coupler.
Meant the rubber coupler...
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NOT the carb...
Just getting my post count up. Gotta beat Slinger ;D
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Sounds like we're getting somewhere! I'm trying to synthesize all of the information I've received and want to be sure about my next steps.
- Is the gap in the photo actually a problem?
- Does the diaphragm being shot explain the problems that I have been having, or is that a separate issue? Any idea where can a find a replacement diaphragm?
- Is is certain that I need to replace / repair the manifold, or should I try testing with start spray first? (Then again, a new manifold probably doesn't cost TOO much more than start spray!) Based on the photo it looks like I would need the manifold with two vacuum points. Is that correct?
As always, thanks for sharing your knowledge.
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For starters... Surging is almost ALWAYS caused by air leaks. The worse the leak the more surging. It will eventually melt the piston or valves due to a lean fuel ratio. Spraying starting fluid MAY cause a fire so I tend to spray water to test. That will cause the engine to stall vs explode. (no choice there). The Diaphragm issue is separate but will cause slow throttle response, and lowered power. http://www.partsforscooters.com/Welcome?search=carb+diaphragm (http://www.partsforscooters.com/Welcome?search=carb+diaphragm)
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Forgot... Just look at your manifold... If it has two hoses you need two ports.
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Parts update: I ordered a new intake manifold, gasket, O-ring, and carb diaphragm.
Performance update: The scooter dying at stops seems to be getting worse. Maybe happens once every 15 times, but when it happens it's always as I'm coming to a stop. If I manage to come to a stop with the scooter at its normal idle it doesn't sputter and die.
Question: Pardon my denseness here, but I'm still not 100% clear on whether the gap where the manifold meets the engine is a problem? Anyone know?
Thanks! Parts should be here this week.
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Parts update: I ordered a new intake manifold, gasket, O-ring, and carb diaphragm.
Performance update: The scooter dying at stops seems to be getting worse. Maybe happens once every 15 times, but when it happens it's always as I'm coming to a stop. If I manage to come to a stop with the scooter at its normal idle it doesn't sputter and die.
Question: Pardon my denseness here, but I'm still not 100% clear on whether the gap where the manifold meets the engine is a problem? Anyone know?
Thanks! Parts should be here this week.
The gab is between the plastic dress and the manifold, so its nothing to be worried about. To check if there is a real gab between the manifold and the engine (underneath the dress), you can do as Zombie suggested and vapourize some water around the manifold and the opening. :)
About installing the new manifold: Be gentle.
If you tighten too much, you will pull the bolt apart, and it will take half an hour just to get the bolt out, if you have only got a pliers. :D
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Judging from your Picts... Remove the air filter box, and try to pull the back of the carb toward the right side of the scoot. I believe you will see a crack where the front hose clamp tightens. That is where I believe the issue is. Like Baddi said the gap is a Non issue
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Judging from your Picts... Remove the air filter box, and try to pull the back of the carb toward the right side of the scoot. I believe you will see a crack where the front hose clamp tightens. That is where I believe the issue is. Like Baddi said the gap is a Non issue
What is the "air filter box"? I'll give this a shot tomorrow.
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The box that the air filter is in... ::)
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Carb intake
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Carb intake
Is that the same as the intake manifold? If so, I'll be replacing that on Thursday or Friday.
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No. The other side of the carb!
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PROBLEM!!!!
I replaced the carb diaphragm and the scooter started fine. I then tried replacing the intake manifold. I took off the old manifold and everything looked fine but decided to try putting on the new one anyway. It didn't fit (couldn't screw down the two nuts all the way to fully secure it) so I put the old one back on. Now the scoot won't start!!! It cranks but doesn't go anywhere. All hoses appear to be in place just fine. I'll try taking off the manifold and putting it back on, but this definitely sucks.
Help, please!
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PROBLEM!!!!
I replaced the carb diaphragm and the scooter started fine. I then tried replacing the intake manifold. I took off the old manifold and everything looked fine but decided to try putting on the new one anyway. It didn't fit (couldn't screw down the two nuts all the way to fully secure it) so I put the old one back on. Now the scoot won't start!!! It cranks but doesn't go anywhere. All hoses appear to be in place just fine. I'll try taking off the manifold and putting it back on, but this definitely sucks.
Help, please!
And... in one of the more embarrassing moments of my life I admit that I just spent 2.5 hours ridiculously frustrated, only to figure out that I had accidentally hit the kill switch at some point prior. A mechanic friend reassured me that it's a mistake that everyone makes precisely one time in their life, but man, what an emotional roller coaster of a night!
Time to go check this thing out on the road.
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The latest news:
- The scooter runs just fine and it seems as though it doesn't sputter / consider dying at stops anymore. The ride wasn't terribly long so it's possible that it was just kidding about this :-)
- The surging issue is still there and it's now occurring at WOT / a bit under WOT around 45 MPH, whereas previously it only occurred at WOT above 50 MPH. A friend who knows bike engines should be coming over sometime in the next few days and hopefully we can figure something out. I'm guessing that it is related to the intake manifold, though, if that's the main thing that I played around with today (other than the diaphragm).
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Im glad you got it running again , running more of the seafoam and fresh gas through your system might still help out your issues . Good luck and enjoy your scoot ! P.S. I have had the same accident with the kill switch , it happens more often than you would think .