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Post by xiholdtruex on Nov 25, 2013 10:21:22 GMT -5
i have a 150cc jonway scooter from 2003, I took it to my local scooter mechanic when it was giving me a problem where it would sometimes start and shut off, and when it would finally start it would only idle at or above 3000 rpm. I changed the ignition coil the cdi and the carb from what the mechanic said it was the carb that was the issue. Now these are all new and its still giving me the same issue as before and I dont want to take it back to a mechanic that apprerntly does not know what he is talking about and trying to shotgun it. Any point in the right direction would be a great help,
Thanks in advance
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Post by millsc on Nov 25, 2013 11:05:59 GMT -5
Your gonna have to get your hands dirty and take it apart start with the valves it could be valves out of adjustment,could be bad rings and even a hole in the piston which I have seen a bunch.
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Post by xiholdtruex on Nov 29, 2013 12:27:28 GMT -5
I pulled the fuel lines to make sure it has gas flow and it was drowning the engine, when I disconnect the line and cranked it the engine started, but when I put the line back on and try to start it , it wont start it ill just turn over. Does anyone know what I could do to fix this? or what is causing this problem?
Thanks in advance
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Post by JerryScript on Nov 29, 2013 13:22:05 GMT -5
If the line you are disconnecting is the fuel line and not the vacuum line, then it would appear to be the fuel petcock is not opening. This could be due to the petcock being bad, or the vacuum line not holding the vacuum pressure. First check the vacuum line going to your valve cover, be sure there are no kinks or cracks, and it has a good seal. Next, check the fuel petcock by removing the vacuum line from the valve cover and the fuel line from the bottom of the carb, then suck on the vacuum line and if the petcock is OK fuel should pour out the fuel line, if not the petcock is bad.
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Post by Mainely Scooters on Dec 2, 2013 0:54:35 GMT -5
From what you describe the engine is flooding. Assuming you are getting a constant fuel flow *without* vacuum on the vacuum line then the fuel petcock is bad. You can follow JerryScript's instructions to test it.
However, even if the petcock is bad the carb FLOAT VALVE should cut off extra fuel flow. If you take off the carburetor and remove the bottom "bowl" you will see a big plastic piece (generally white, sometimes black) inside that moves freely up and down. If you blow against the FUEL INLET and move the float up and down, when the float is up it should cut off the air. If it doesn't the valve needs to be cleaned and possibly the needle valve replaced. If you are confident in your mechanical skills you can attempt to disassemble it and clean it. Be careful for SMALL PARTS. If you're not comfortable you might need to replace it.
Be advised, if you replace your carburetor you may need to swap the jets from your old one to your new one. It depends on what jets come with your new one. They vary. Idle jet (long thin) and main jet (small).
From what you describe that is the issue.
You should adjust your valves anyway. Lots of videos and how-to's floating around. .004" intake and .005" exhaust.
Greg
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Post by alleyoop on Dec 2, 2013 2:22:00 GMT -5
If it only wants to run at high rpms 3000+ the first thing you want to do is Adjust the Valves. Most likely the exhaust valve is staying open and loosing compression and will be very hard to start and since your cranking it trying to start it is flooding the motor with to much fuel.
Adjust the Intake Top Valve to .004 Inchs and the bottom Exhaust Valve to .004 Inchs or .005 inchs. I adjust mine both to .004 inchs.
You do not need to change any jets you have not modded the scoot to warrant changing anything. It is just needs some fine tuning that is all.
Alleyoop
Here is a Video on how to adjust your valves:
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..BAD TO THE BONE..