Kymco Agility 125- Slow warm up and stumbling idle issues...PROBLEM RESOLVED!!!

Discussion in 'Battle Scooters' started by wheezyryder, Aug 12, 2015.

  1. wheezyryder

    wheezyryder Punk in Drublic

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    Hello all from a frequent lurker and infrequent poster. I recently acquired a 2009 Kymco Agility 125 from Craigslist to use as a run-around bike and to put me in the multi-bike owner’s club (2004 Kawi KLR650). I bought it as a non-runner and have it running well for the most part now but I’m having trouble getting the idle to my liking.

    A little background on the scoot. Got it for $350 with 950 kilometers on the clock. It had been bought new, ridden for a month, wrecked hard enough to bend the steering stem, then stuck in a basement and not started for 5 years. I replaced the battery, drained the old fuel, flushed the tank, replaced the fuel lines and thoroughly cleaned the carb. After that it started and ran well for one day before it lost spark. After much wailing and gnashing of teeth I discovered that the CDI was bad and replaced that. It ran well for about 10 miles then died on me. Tested the battery and discovered it to be low (12.55v). Charged it and now it’s been running well overall for about a week and 150 miles.

    I have 2 idle problems:

    #1) It takes quite a while to warm up to a point where it will idle reliably. Temps are in the 75-95 degree F range here in Georgia right now. I replaced the auto bystarter (enrichener) with a plunger style manual enrichener as a part of my early trouble shooting to get the scoot running. I had read that that part fails commonly and I just don’t like the idea of not controlling the choke myself. The bike starts up immediately with the choke plunger pulled. Unfortunately this manual choke has a spring-loaded self-closing feature so I can’t just leave it idling unattended or ride off with the choke open. So generally I just ride off immediately in an effort to warm up the engine quickly. For the first 3-4 miles I have to feather the throttle at stop lights to keep it from stalling. Is this normal? I’m used to my KLR which will idle off choke almost immediately even on cold days. A couple of solutions I thought of:

    -Put the auto bystarter back on. I know that it automatically stays open for quite a while and I’m sure this would help the cold idle. But I really don’t like the idea of an auto choke.

    -Figure out a way to make the manual choke stop self-closing.

    -Replace the main jet and/or idle jet with a richer jet. I know that the idle on my KLR got much less finicky when I put in a richer main jet. I realize that the main jet mainly controls the mix at open throttle but I think it also has some effect on the idle as well. I think the bike is in a slightly lean condition overall as is common with factory jetting.

    #2) When fully warmed up the bike will idle reliably without any throttle input. However, it still occasionally sounds like it is stumbling or “missing”. I have adjusted the idle mix screw to the point that it idled at highest RPM and then turned it a quarter turn richer. I kept turning the throttle stop screw to raise the idle hoping that this would fix the stumbling/missing. I currently have it as high as it will go without engaging the clutch at idle. I’m not sure what the RPMs are as the bike doesn’t have a tach.

    -Is this just the way the GY6 runs?

    -Could it be caused by a lean condition?

    -Could it be caused by a float level problem? Float not allowing enough fuel and starving it or allowing too much and drowning it?

    Apologies for the lengthy post. I hope some of you were able to stay with me through the whole thing. Does anyone have experience with the GY6 or have any ideas to fix the idle issues?
    #1
  2. tortoise2

    tortoise2 Been here awhile

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    If you have not already done so . . blow out intake air filter with compressed air and check valve clearances. Verify there are no cracks in the intake manifold, file off any carb outlet casting bumps, and apply a light smear of silicone grease (not sealer) to carb-manifold join surfaces. Verify throttle bore fuel ports are not obstructed.



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    #2
  3. wheezyryder

    wheezyryder Punk in Drublic

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    Thanks for the reply Tortoise. The air filter is clean as new and I already adjusted the valves (much easier to adjust than the KLR). I definitely cleaned the throttle bore fuel ports. I actually cleaned the carb 3 times. When I first started working on it I cleaned the carb and flushed the tank and it started right up but quit running after a minute or so. When I took the carb apart again I found new trash in it. Finally figured out that the old fuel lines were breaking down on the inside and shedding trash into the newly cleaned carb. Fuel lines replaced.

    I hadn't thought about a vacuum leak but now that you mention it it might fit the symptoms. I did check the rubber intake boot and manifold and saw no obvious cracks. I will pull the carb and check for casting imperfections. And I like the idea of silicone grease to ensure tight fit between the carb and manifold I'll definitely do that. Maybe before I pull the carb off I'll spray carb cleaner on the carb and all the vacuum connections to see if it lowers the idle.

    #3
  4. Jim Moore

    Jim Moore "You ain't black!"

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    I might try re-installing the auto bystarter. My stock A125 (31K kms) starts up every time and vrooms off immediately.
    #4
  5. wheezyryder

    wheezyryder Punk in Drublic

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    Jim do you have to do a lot of feathering of the throttle when it's cold? Do you know if the auto bystarter closes automatically in a certain amount of time or does it respond to the increase in temp? I'm gonna work in it later today. First I'm gonna spray carb cleaner on it to check for vacuum leaks. Then I'll check the carb to make sure all the fuel ports are clean and put silicone on the intake and manifold junctions. Will also reinstall the auto bystarter.

    On a side note I really do like this scoot. It's my first scooter. I live in the middle of Atlanta and I work 4 miles away. Rarely have to get on the highway. I really like that the scoot is so easy to hop on and take off. Plus in my part of town there are plenty of areas where nobody minds if you park a scoot on the sidewalk.
    #5
  6. Jim Moore

    Jim Moore "You ain't black!"

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    Not one bit. Literally it's start up and go, at whatever throttle I feel like.

    I've never messed with the carb on this thing, but I think it's based on engine heat.
    #6
  7. wheezyryder

    wheezyryder Punk in Drublic

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    So I rode the scoot up to Ace Hardware to pick up some silicone grease and to warm up the engine so it would idle. Then I came home, removed the seat and engine cover, started the engine and sprayed carb cleaner at all of the junctions where it could have a vacuum leak. When I sprayed the junction of the carb to the intake manifold the engine idle increased significantly. So I disconnected the carb from the rubber boots coming from the air box and the intake manifold. Applied the silicone grease and careful reconnected everything making sure to seat the boots and thoroughly tighten the clamps. When I started it up it immediately idled a lot faster than it had before I took it apart. I readjusted the idle air screw and the adjustments were much more positive than before. In other words each quarter turn of the screw resulted in changes in the idle speed in a nice linear progression whereas before it had been wishy-washy. The screw is now at 2 1/4 turns out instead of 3 1/2 turns out. After adjusting the idle air screw the idle speed was quite high so I backed off the throttle stop screw a good bit. It seems to idle well now with none of the "missing" it had been doing before. Wasn't able to take it for a proper test ride due to rain so I'm not going to call it fixed just yet.

    I decided to wait to reinstall the auto bystarter until after I've had time to test ride it and confirm that the idle problem is fixed. Don't want to make multiple changes at once. Also the idle may be improved enough that I don't have to go back to the auto bystarter. Makes sense that if I had a vacuum leak I was running way lean at all RPMs. Will report back after a test ride.
    #7
  8. wheezyryder

    wheezyryder Punk in Drublic

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    After riding around for a while and periodically stopping to check the idle and raise the idle with the throttle stop screw, I don't think the problem is fixed. Still missing at idle. Have to work tomorrow but on Saturday I'm going to spray it with carb cleaner again to see if I still have vacuum leaks. If it seems like I do I'll continue trying to fix the leak. If not maybe I'll pull the carb apart and check the idle jet and the fuel passages in the carb throat again.
    #8
  9. wheezyryder

    wheezyryder Punk in Drublic

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    New symptom. The idle also seems to be erratic. Sometimes low and stumbling. Sometimes so high it is partially engaging the clutch.
    #9
  10. fullmetalscooter

    fullmetalscooter Let me take this duck off

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    Do you see if rubber manifold that the carb attaches to has any cracks in it ? Stab in the dark but on helix , elite and other they do crack and cause issues.
    #10
  11. wheezyryder

    wheezyryder Punk in Drublic

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    I inspected the rubber manifold for cracks and didn't see anything obvious. But at this point I still suspect a vacuum leak somewhere. Later today I'm gonna go back through and check for sources of vacuum leaks. I read about a method of identifying vacuum leaks by holding something smoky like a lit cigarette near suspected leak sources. Theoretically the leak will pull the smoke in and allow me to see where the leak is. Progress update forthcoming later today.
    #11
  12. Dan V.

    Dan V. Been here awhile

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    As you have toyed with the bystarter .......My bystarter went bad on my vino 125, and I wasn't about to pay Yamaha $325- for a new one. So out of parts I made a manual choke that used the body of the old bystarter. Worked as it should , but idle could be wonky. Discovered that the o-ring was stretched and wouldn't seal right so reinstalled it with some Yamabond sealer. Problem solved.

    So your problem may be something similar - it had to be a very small air leak, but being in the idle circuit things weren't right.
    #12
  13. wheezyryder

    wheezyryder Punk in Drublic

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    Thanks Dan I hadn't thought about that. The manual choke I ordered uses the body of the old bystarter. It was a bit fiddly trying to get the little gasket to stay in place while installing it while the carb was still mounted to the engine. I'm headed out right now to attempt further vacuum leak testing. I'll also check that little gasket.
    #13
  14. wheezyryder

    wheezyryder Punk in Drublic

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    Well I went out for a ride to warm it up. Came back and tried the cigarette smoke trick to search for vac leaks. That didn't work as the cooling fan on the GY6 blows all of the smoke away. Next I started visually checking the intake manifold and all the vacuum connections with a flashlight looking for tiny cracks/leaks.
    I found a vac line from the air box that I hadn't noticed before. I tried to add a pic of the line from Flickr without success sorry about that. It sits directly underneath and behind another line. It was completely disconnected. Right now I'm waiting for the scoot to cool down again so I can test it. Hopefully this was the problem.
    #14
  15. tortoise2

    tortoise2 Been here awhile

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    Imgur guidelines.

    If you post a YouTube video, be sure to select the "public" setting . . no can see (so far) example.
    #15
  16. wheezyryder

    wheezyryder Punk in Drublic

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    Well it looks like that wasn't it. Reconnected that line and still having the same problems. I'm going to try to hunt for vac leaks again. Also going to remove the manual choke and reinstall the auto bystarter making sure that the rubber o-ring is properly seated.

    Tortoise I'll work on my picture posting issues a bit later tonight.
    #16
  17. wheezyryder

    wheezyryder Punk in Drublic

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    I removed the manual enrichener and reinstalled the stock auto bystarter and that seems to have fixed my rough idle problems. I want to ride it around for a while and go through a couple of cold starts before I call it completely resolved but the idle was much smoother with no stumbling on my test ride. Haven't yet tried to figure out exactly why the manual choke didn't work. Maybe the rubber o-ring wasn't sealing properly? Maybe the choke plunger didn't exactly match the profile of the enrichener port and wasn't sealing it completely in the closed position? I'll look into it next time I have time to tinker with the scoot. For now I would like to just ride it for a while after a month and a half of obsessive tinkering! I'll report back as to whether or not the problem is truly fixed.
    #17
  18. fullmetalscooter

    fullmetalscooter Let me take this duck off

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    glad you fixed it . Sorry if I lead you in the wrong direction .
    #18
  19. wheezyryder

    wheezyryder Punk in Drublic

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    On the contrary fullmetalscooter I appreciate everyone's suggestions. I've found that most of the time I hit a dead end while wrenching I just need people to run some new ideas by me. Honestly I suspected the intake manifold more than I did the enrichener I was surprised when that fixed it.

    At this point I do think it's fixed. Today was the first day of what is supposed to be week of rain in Atlanta but I rode anyway because I wanted to test it some more. It started no problem, idled without feathering the throttle, and continued to idle well as it warmed up on the 4.5 mile ride to work. Same thing on the way home.

    Thanks for everyone's help and suggestions! Now it's time to ride the hell outta this thing!
    #19