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Post by sdsbassist on Jun 16, 2019 17:49:07 GMT -5
So I consider myself moderately a less to fix and troubleshoot bikes. Have had many of them.
Guy I know bring me this chinese scooter. New battery it starts and idles great. Any throttle it kills. It has sat for 5 years.
Tried new carb, new cdi, new coil and new plug. Flushed out old gas and new gas in.
I'm used to vintage bikes. Not sure what's up here. Timing? Valves?
Only has 129 miles.
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Post by tortoise2 on Jun 16, 2019 18:19:36 GMT -5
Posting images may help . . example. Unclear if 50cc or 125/150cc . . floor-level or under-seat gas tank?
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Post by sdsbassist on Jun 16, 2019 18:20:26 GMT -5
It's actually a 250. Under the seat with a fuel pump.
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Post by tortoise2 on Jun 16, 2019 18:38:20 GMT -5
It's actually a 250. Under the seat with a fuel pump. Horizontal cylinder Yamaha Linhai style . . or vertical cylinder Honda Helix style?
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Post by sdsbassist on Jun 16, 2019 18:41:31 GMT -5
Fuel comes out of pump when you start. New carb. New coil, new plug. Fresh gas. Not sure what I'm missing.
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Post by aeroxbud on Jun 16, 2019 19:00:35 GMT -5
Check the air filter, and exhaust. Little critters like making homes in unused bikes.
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Post by pinkscoot on Jun 16, 2019 19:06:43 GMT -5
Are you running the stock airbox? Have the valves been adjusted? did you have the problem before you replaced everything? Did you use OEM parts or "performance" parts? Did you check the intake to see if its cracked? Is the intake sealing to the cases properly, O-rings may have shrunk from sitting? Does the Carb have the same jets and needles as the original?
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Post by sdsbassist on Jun 16, 2019 19:53:15 GMT -5
Are you running the stock airbox? Have the valves been adjusted? did you have the problem before you replaced everything? Did you use OEM parts or "performance" parts? Did you check the intake to see if its cracked? Is the intake sealing to the cases properly, O-rings may have shrunk from sitting? Does the Carb have the same jets and needles as the original? Stock airbox No valve adjustment. Would they get out of sync at 100 miles? Have not checked intake Yes looks to be the same carb setup This was all happening before the change. What's a good way to tell if there is a nest in the exhaust?
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Post by pinkscoot on Jun 16, 2019 20:03:45 GMT -5
When its idling is there exhaust coming out? Pull the exhaust and shake it. run a heat gun or torch and burn it out. You problem sounds like a lean condition caused by an air leak.
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Post by sdsbassist on Jun 16, 2019 20:06:47 GMT -5
When its idling is there exhaust coming out? Pull the exhaust and shake it. run a heat gun or torch and burn it out. You problem sounds like a lean condition caused by an air leak. So here is the question. What does it take to access this all correctly. How much plastic has to come off? It seems like a real pain to access everything. Anything that's a more typical culprit? I appreciate everyone's help
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Post by pinkscoot on Jun 16, 2019 20:31:48 GMT -5
Welcome to the world of Chinese scooters, actually most scooters with plastics.
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Post by SMALL CC TEK on Jun 19, 2019 20:48:54 GMT -5
Pull the hose off the air intake start the scoot stick a long screwdriver in the carb and lift the slide at the same time open the butterfly and see if it revs up .. If it does you have a diaphragm issue or needle clip off or pin hole .. Some dont have clips on the needle so just epoxy that small spacer on the needle if that is it
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Post by GrumpyUnk on Jun 20, 2019 11:35:31 GMT -5
A thought is that the slide can get stuck or gummed up and not move. If it was frozen/stuck, opening the throttle would make it struggle, as airflow would not match what the throttle plate was expecting, and the mixture would go to beans. I'd remove the intake tube from the air cleaner end, and make sure the slide is free to move. Even a new carb could have a slide that's on the sticky side, especially if it was 'lubed for shipment', and it has sat on a shelf for a while. i.e., couldn't hurt to make sure it's free to move. Have you tried a gravity feed? The tank, outlet tube & screen, the petcock, vacuum valve, etc could all be sticky, or 'stuff' from storage could have plugged things up. If you disconnect the fuel inlet at the carburetor, you should see full diameter flow once the line/petcock is opened up. If you went with a 'performance' CDI you may find it harder to start as most set the timing advance a bit more aggressively at low rpm. That will make it want to kick back a bit. But it reportedly starts and idles well. Falling on its face could be the accelerator pump(if equipped) that is operated by the flat lever on the throttle plate linkage. As the throttle opens, the lever moves, and immediately starts to depress the accelerator pump shaft, squirting fuel into the intake. If you don't have that it will stumble. They may come from the factory with some slop in the linkage so the pump is not poked when it should be. Have you checked that the float valve works properly? Some have sticky needles right out of the box. Low fuel level would lean out the mix too much. If the idle jet is adjustable, you could try opening a partial turn. Some carbs depend on a 'fat' idle mix to transition to higher speed circuits. tom
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