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Post by mikehailwood on Feb 14, 2020 9:21:00 GMT -5
The Kymco carb is so much better that's all . The consistency is the issue with the Chinese ones. Do you have the same size jets in the Chinese as Kymco carb or close ? Sometimes you must tear the new Chinese carb down and basic blueprint it so it works properly ... Making sure the floats are adjusted right ,making sure the slide is smooth and diaphragm is working and not leaking etc making sure the jets are what you need for your motor . Making sure the jets are clean even if it's new never used etc ... Like the others here say if you have a pod filter and not a bunch of experience tuning it will be so tough for you ! I agree that the Kymco OEM carb is of much better quality. I also agree with most of your other comments. But...since the Chinese carb will not hold an idle and clearly has a leak I must address this issue before worrying about float height, jet sizes, etc. When testing for air leaks, I sprayed starting fluid at the head side of the manifold (no leak) and at the carb side of the manifold (big leak). I assumed the leak was coming from this connection. Could the leak be somewhere else close by on the carb body? I have re-attached the manifold to the carb with the OEM clamp. It seems quite tight. Temperatures have plummeted here and I will not be able run the bike for a few days. When I do, I will report the results.
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Post by FrankenMech on Feb 14, 2020 19:24:17 GMT -5
Thanks! The translations in manuals leave much to be desired, both from Japanese and Chinese. As a translation bystarter makes no sense at all while enricher does.
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Post by GrumpyUnk on Feb 18, 2020 14:29:18 GMT -5
The Kymco shop manual called it a bystarter. But then again, Engrish. (say it out loud).
The rubbery end of the elbow should be a snug fit to the carb outlet. When clamped, you should not be able to rotate the carb in the rubber bore without a good effort. If it leaks there, you may make an effective repair(temp fix) by coating the inner diameter of the rubber with some RTV silicone. Then stab the carb into the rubber inlet. Let is sit for a while(place a dab of RTV somewhere close so you can use it to gauge the 'set' of the RTV in the bore) until the RTV is close to setting, then tighten the clamp some. The RTV will conform. Let it cure completely, then tighten the clamp. You should effect a good airtight seal. Many of the float bowls on machines that have been left with fuel in the carb end up with a plugged orifice that allows fuel into the bystarter bore. When that happens, you will find starting difficult. The orifice should be checked before assembly. I had carbs I thought clean that would never start an engine. They'd pop and snort, but not run. Finally found that needle size orifice, cleaned it and they started to work. I guess this is a 'hidden secret' that is now out. The orifice allows the fuel in the float bowl to fill the larger diameter of the enrichment pickup, SLOWLY. You get a full pickup area after a while, but it will just sit until the enrichement is enabled. When starting, you'd get a pretty good snort of fuel for a short while until the fuel in the bore was consumed, then the refill at a much slower rate would ensue, with the engine hopefully started and running. If the orifice is plugged, you get no extra 'startup' fuel, and difficult starting.(if at all). The 'bystart' should be opened at 'room temperature', and you should be able to blow through it into the intake using a length of rubber tubing(the port is on the right side upper of the inlet side of the carb). When it has been heated by the engine running for a while, or 12CV connected across the terminals, you should NOT be able to blow through the bystart valve. If you can, it is defective(per Kymco manual). The Kymco manual is for the Super 9, available on the web(somewhere), and it covers both the AC and WC versions. It is also written in Engrish. tom
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Post by mikehailwood on Feb 19, 2020 8:44:38 GMT -5
Installed everything using the original clamp yesterday and had a few minutes to play with it. There now seems to be no leak in the manifold to carb connection area. That's one issue addressed but things are still not right. I have noticed that the higher rpm start up speeds don't happen every time I cold start this thing. Grumpyunk's comments regarding the bystarter gave me something else to inspect. The fuel for the enricher comes from a small float bowl cavity fed by a small hole connecting to the main float bowl chamber. I've seen this arrangement on some small Honda carbs. The connecting hole can become clogged, just like an idle jet. Also, even though this is a "new" Chinese carb, I did notice some gray sludge when examining the inner workings of the accelerator pump when I first received the carb. Could be some "gray sludge" blocking the connecting hole to the enricher fuel supply cavity. I'll make sure this hole is completely open. If I can get the enricher to run the machine at higher rpm's every time, the engine should run long enough to warm up and properly idle down. Then I can do some tuning.
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Post by wiscootsin on Feb 19, 2020 13:29:47 GMT -5
I just got two 2007 kymco agility 50s that were abandoned to run. On one of them the initial problems i encountered (that seem a bit similar to yours, even put a cheap chinese carb on it) were fixed fully after i changed the oil. With the original oil it ran crappy and wouldn't idle right until i got it running long enough (with throttle) that the engine was warm enough for the oil to be less resistant (that's my guess anyway). After that i immediately changed the oil and it runs fine.
But maybe you changed the oil right away and this doesn't help.
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Post by mikehailwood on Feb 19, 2020 14:04:47 GMT -5
I just got two 2007 kymco agility 50s that were abandoned to run. On one of them the initial problems i encountered (that seem a bit similar to yours, even put a cheap chinese carb on it) were fixed fully after i changed the oil. With the original oil it ran crappy and wouldn't idle right until i got it running long enough (with throttle) that the engine was warm enough for the oil to be less resistant (that's my guess anyway). After that i immediately changed the oil and it runs fine. But maybe you changed the oil right away and this doesn't help. I installed new rings, valve seals and lapped the valves. After that I changed the oil a couple times. Thanks for the suggestion.
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Post by mikehailwood on Feb 19, 2020 16:04:17 GMT -5
Would there be any value in placing some sort of tube between the carb and the pod filter?
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Post by wiscootsin on Feb 19, 2020 17:58:59 GMT -5
Have you messed with the vacuum lines at all?
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Post by mikehailwood on Feb 19, 2020 18:21:59 GMT -5
"Have you messed with the vacuum lines at all?" I eliminated all vacuum lines.
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Post by mikehailwood on Feb 23, 2020 15:12:09 GMT -5
UPDATE...I checked the float bowl reservoir wall for the bystarter circuit. No blockage there. I removed the pod filter and attached about 7" of 1-1/2" I.D. hose to the air intake side of the carb (no air filter at this point). After the bike started and warmed up I adjusted the idle mixture screw and the idle. The bike is running (on the center stand) and revving much better than it has in quite a while. I'll let it sit and start and run it a few times over the coming days and see how it behaves. I'll install the storage box and seat, then take it for a spin and see what happens - then report back.
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Post by mikehailwood on Feb 28, 2020 12:54:17 GMT -5
Today I rolled it out and ran it on the center stand for while. I added the pod filter to the 1-1/2" hose and played with idle and air screw adjustments. Not much adjustment needed after filter install. Sometimes while idling the RPM's will begin dropping, to the point where I need to turn the idle screw to keep it from dying. It doesn't die and then the RPM's increase to what sounds like a much too high rate. I'll let it cool down and go through the process again after lunch. If it isn't any worse I'll put it back together and take it out for a ride this weekend when the weather warms up.
p.s. No air leak between carb and manifold'
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Post by mikehailwood on Mar 4, 2020 18:56:32 GMT -5
With about 7" of 1-1/2 I.D. hose coming off the carb, the scoot ran okay but did not do well on take-off (bogged badly). It did better when I closed off some of the surface area of the pod filter. Today I put reducer in the end of the 1-1/2" hose which brought the I.D. at the end of about 7/8". It ran pretty well (no filter at all on this run). Does anyone know how long the hose should be from the air intake side of the carb back to the air box?
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Post by GrumpyUnk on Mar 12, 2020 12:17:56 GMT -5
I would go back to stock air filter assembly. Others may want that slight increase in performance, but I find my time better spent on other things than fine tuning a Chinese carburetor. The unstable idle may be due to being at the low end of the 'middle speed' carb circuit. IOW, you may not be on the 'idle circuit' in the carb if the throttle plate is open a bit more than expected. You would then be trying to idle on the higher(middle) speed circuit, which would be unstable. You might try lowering the throttle plate a bit, and fiddling with the idle needle jet to set the idle. OTOH, it could be something else. IMO, best to start with stock, get it to run/idle/accelerate etc using that before trying other air intake modifications. Once you have the carb solid, you can then diddle with the knowledge that it should run with settings close to what you have. Remember that a bit of restriction due to the factory setup is dialed into the carburetor, and it may run too lean when that restriction is removed... tom
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Post by mikehailwood on Mar 12, 2020 16:12:45 GMT -5
Thanks for the input, tom. I may not have mentioned that the reason I added a pod filter was because this junker did not come with the stock air box. To recap, the stock carb had a badly damaged idle jet which I thought I could not remove without damaging the carb. The float valve leaked. And the bystarter did not seem to work and tested bad. After fiddling with the Chinese carb I decided to swap Chinese carb components over to the Kymco carb. I was able to successfully drill out the damaged idle jet from the Kymco carb with a left hand 1/8" drill bit. The Chinese idle jet fit and the Chinese float valve needle fit. The bike ran better but still would not idle. I traced this to air coming in around the air screw so I replaced all air screw components with the Chinese parts (needle, spring, washer and o-ring). Now it idles. It is still hard to start. I need to install the Chinese bystarter next, since I know it worked when the Chinese carb was installed.
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Post by SMALL CC TEK on Mar 12, 2020 17:36:50 GMT -5
Find a air box ! It will save you a lot of hassle a weather change and boom your starting this all over again ! lol Kymco boxes are expensive and chinese one could work if you get the long case version and i think you will need to fab a small bracket for the bottom, cause a Kymco case does not have the same bolt spacing !
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